Publications by authors named "Konrad J Domig"

51 Publications

Biofilm-Forming Ability of and Considering Physicochemical and Topographical Surface Properties.

Foods 2021 Mar 13;10(3). Epub 2021 Mar 13.

Institute of Food Technology, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria.

Biofilm characteristics of D84 () and subsp. () on polytetrafluoroethylene and AISI-304 stainless steel at early- (24, 48 h) and late-stage (144, 192 h) biofilm formation were investigated. biofilm structure was more developed compared to , representing vastly mature biofilms with a strongly developed amorphous matrix, possibly extracellular polymeric substances (EPSs), at late-stage biofilm formation. showed faster growth behavior but still resulted in a relatively flat biofilm structure. Strong correlations were found between several roughness parameters and surface coverage (r ≥ 0.98), and between total surface free energy (γs) and surface coverage (r = 0.89), while remained mostly unaffected. The pronounced ubiquitous biofilm characteristics make D84 a suitable model for biofilm research. Studying biofilm formation of these bacteria may help one understand bacterial adhesion on interfaces and hence reduce biofilm formation in the food industry.
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http://dx.doi.org/10.3390/foods10030611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8001712PMC
March 2021

The Impact of Sampling Season and Catching Site (Wild and Aquaculture) on Gut Microbiota Composition and Diversity of Nile Tilapia ().

Biology (Basel) 2021 Mar 1;10(3). Epub 2021 Mar 1.

Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), Muthgasse 18, 1190 Vienna, Austria.

The gut microbiota of fishes is known to play an essential role in diverse aspects of host biology. The gut microbiota of fish is affected by various environmental parameters, including temperature changes, salinity and diet. Studies of effect of environment on gut microbiota enables to have a further understanding of what comprises a healthy microbiota under different environmental conditions. However, there is insufficient understanding regarding the effects of sampling season and catching site (wild and aquaculture) on the gut microbiota of Nile tilapia. This study characterised gut microbial composition and diversity from samples collected from Lake Tana and the Bahir Dar aquaculture facility centre using 16S rDNA Illumina MiSeq platform sequencing. Firmicutes and Fusobacteria were the most dominant phyla in the Lake Tana samples, while Proteobacteria was the most dominant in the aquaculture samples. The results of differential abundance testing clearly indicated significant differences for Firmicutes, Fusobacteria, Bacteroidetes and Cyanobacteria across sampling months. However, Proteobacteria, Chloroflexi, Fusobacteria and Cyanobacteria were significantly enriched in the comparison of samples from the Lake Tana and aquaculture centre. Significant differences were observed in microbial diversity across sampling months and between wild and captive Nile tilapia. The alpha diversity clearly showed that samples from the aquaculture centre (captive) had a higher diversity than the wild Nile tilapia samples from Lake Tana. The core gut microbiota of all samples of Nile tilapia used in our study comprised Firmicutes, Proteobacteria and Fusobacteria. This study clearly showed the impact of sampling season and catching site (wild and aquaculture) on the diversity and composition of bacterial communities associated with the gut of Nile tilapia. Overall, this is the first study on the effects of sampling season and catching site on the gut microbiota of Nile tilapia in Ethiopia. Future work is recommended to precisely explain the causes of these changes using large representative samples of Nile tilapia from different lakes and aquaculture farms.
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http://dx.doi.org/10.3390/biology10030180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8001861PMC
March 2021

Strain-Dependent Cheese Spoilage Potential of .

Microorganisms 2020 Nov 22;8(11). Epub 2020 Nov 22.

Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria.

, a Gram-positive, anaerobic, spore-forming bacterium, is considered as one of the main causative agents for spoilage of hard and semihard cheeses. Growth of in cheese is critically influenced by ripening temperature and time, pH, salt and lactic acid concentration, moisture and fat content, and the presence of other microorganisms. Previous studies revealed high intraspecies diversity of strains and variable tolerance toward pH, temperatures, and salt concentrations. These findings indicate that strain-dependent characteristics may be relevant to assess the risk for cheese spoilage if clostridial contamination occurs. In this study, we aimed to compare the phenotypes of 12 strains which were selected from 157 strains on the basis of genotypic and proteotypic variability. The phenotypic analysis comprised the assessment of gas production and organic acid concentrations in an experimental cheese broth incubated at different temperatures (37, 20, and 14 °C). For all tested strains, delayed gas production at lower incubation temperatures and a strong correlation between gas production and the change in organic acid concentrations were observed. However, considering the time until gas production was visible at different incubation temperatures, a high degree of heterogeneity was found among the tested strains. In addition, variation among replicates of the same strain and differences due to different inoculum levels became evident. This study shows, that, among other factors, strain-specific germination and growth characteristics should be considered to evaluate the risk of cheese spoilage by .
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http://dx.doi.org/10.3390/microorganisms8111836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7700369PMC
November 2020

Functional Properties and Sustainability Improvement of Sourdough Bread by Lactic Acid Bacteria.

Microorganisms 2020 Nov 30;8(12). Epub 2020 Nov 30.

BOKU-University of Natural Resources and Life Sciences Vienna, Department of Food Science and Technology, Muthgasse 18, 1190 Vienna, Austria.

Preventing food spoilage without the addition of chemical food additives, while increasing functional properties of wheat-based bakery products, is an increasing demand by the consumers and a challenge for the food industry. Within this study, lactic acid bacteria (LAB) isolated from sourdough were screened in vitro for the ability to utilize the typical wheat carbohydrates, for their antimicrobial and functional properties. The dual culture overlay assay revealed varying levels of inhibition against the examined fungi, with S4.2 and S2.9 exhibiting the highest suppression against the indicator strains MUCL43764, , MUCL11945, DSM1988, and DSM1079. Furthermore, the antifungal activity was shown to be attributed mainly to the activity of acids produced by LAB. The antibacillus activity was evaluated by the spot-on-the-lawn method revealing a high inhibition potential of the majority of LAB isolated from sourdough against DSM31, DSM13, LMG7135, and S15.20. Furthermore, evaluating the presence of the glutamate decarboxylase gen in LAB isolates by means of PCR showed a strain dependency of a potential GABA production. Finally, due to improved functional activities, LAB isolated from sourdoughs exhibit promising characteristics for the application as natural preservatives in wheat-based bakery products.
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http://dx.doi.org/10.3390/microorganisms8121895DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7760938PMC
November 2020

Insights into the Potential of Sourdough-Related Lactic Acid Bacteria to Degrade Proteins in Wheat.

Microorganisms 2020 Oct 30;8(11). Epub 2020 Oct 30.

Institute for Animal Nutrition and Feed, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220 Vienna, Austria.

Sourdough processing contributes to better digestible wheat-based bakery products, especially due to the proteolytic activity of lactic acid bacteria (LAB). Therefore, sourdough-related LAB were screened for their capacity to degrade immunogenic proteins like gluten and alpha-amylase-trypsin inhibitors (ATIs). Firstly, the growth of 87 isolates was evaluated on a gluten-based medium. Further, the breakdown capacity of selected isolates was determined for gluten with a focus on gliadins by measuring acidification parameters and MALDI-TOF MS protein profiles. ATI degradation after 72 h of incubation within an ATI-based medium was investigated by means of acidification, HPLC, and competitive ELISA. All isolates exhibited the potential to degrade ATIs to a high degree, whereas the gliadin degradation capacity varied more greatly among tested LAB, with Lpa4 exhibiting the strongest alterations of the gliadin pattern, followed by Lpl5. ATI degradation capacities ranged from 52.3% to 85.0% by HPLC and 22.2% to 70.2% by ELISA, with Lpa4 showing superior breakdown properties. Hence, a selection of specific starter cultures can be used in sourdough processing for wheat-based bakery products with reduced gluten and ATI content and, further, better tolerated products for patients suffering from non-celiac wheat sensitivity (NCWS).
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http://dx.doi.org/10.3390/microorganisms8111689DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693696PMC
October 2020

Characterization of Strains Using Three Different Typing Techniques.

Microorganisms 2020 Jul 16;8(7). Epub 2020 Jul 16.

Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria.

is well known as one of the main causative agents of severe cheese spoilage. The metabolism of this anaerobic bacterium during ripening leads to textural and sensory defects in cheese and consequential loss of product value. The potential to induce cheese spoilage, however, may vary among different strains of the same species. Therefore, a better understanding of the intra-species diversity of may be of practical relevance for the dairy industry. In the present study, we compared the ability of three typing techniques to differentiate 95 strains on the subspecies level: (1) repetitive element palindromic PCR (rep-PCR) fingerprinting combined with conventional agarose gel electrophoresis, (2) hexaplex-PCR followed by an automated capillary electrophoresis and (3) matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) typing. MALDI-TOF MS fingerprinting provided only moderate reproducibility and low discriminatory power. Both PCR-based methods were highly reproducible and discriminative, with hexaplex-PCR fingerprinting being slightly more discriminative than rep-PCR typing. Overall, a high intra-species diversity was observed among the tested strains, indicating that further investigations on the strain level may be of interest.
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http://dx.doi.org/10.3390/microorganisms8071057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7409188PMC
July 2020

Short-Chain Cello-oligosaccharides: Intensification and Scale-up of Their Enzymatic Production and Selective Growth Promotion among Probiotic Bacteria.

J Agric Food Chem 2020 Aug 31;68(32):8557-8567. Epub 2020 Jul 31.

Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Graz 8010, Austria.

Short-chain cello-oligosaccharides (COS; degree of polymerization, DP ≤ 6) are promising water-soluble dietary fibers. An efficient approach to their bottom-up synthesis is from sucrose and glucose using glycoside phosphorylases. Here, we show the intensification and scale up (20 mL; gram scale) of COS production to 93 g/L product and in 82 mol % yield from sucrose (0.5 M). The COS were comprised of DP 3 (33 wt %), DP 4 (34 wt %), DP 5 (24 wt %), and DP 6 (9 wt %) and involved minimal loss (≤10 mol %) to insoluble fractions. After isolation (≥95% purity; ≥90% yield), the COS were examined for growth promotion of probiotic strains. Benchmarked against inulin, trans-galacto-oligosaccharides, and cellobiose, COS showed up to 4.1-fold stimulation of cell density for , subsp. , subsp. , and but were less efficient with sp. This study shows the COS as selectively functional carbohydrates with prebiotic potential and demonstrates their efficient enzymatic production.
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http://dx.doi.org/10.1021/acs.jafc.0c02660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458430PMC
August 2020

Metabarcoding Analyses of Gut Microbiota of Nile Tilapia () from Lake Awassa and Lake Chamo, Ethiopia.

Microorganisms 2020 Jul 13;8(7). Epub 2020 Jul 13.

Institute for Integrative Nature Conservation Research, University of Natural Resources and Life Sciences Vienna (BOKU), 1090 Vienna, Austria.

The Nile tilapia () gut harbors a diverse microbial community; however, their variation across gut regions, lumen and mucosa is not fully elucidated. In this study, gut microbiota of all samples across gut regions and sample types (luminal content and mucosa) were analyzed and compared from two Ethiopian lakes. Microbiota were characterized using 16S rRNA Illumina MiSeq platform sequencing. A total of 2061 operational taxonomic units (OTUs) were obtained and the results indicated that Nile tilapia from Lake Chamo harbored a much more diversified gut microbiota than Lake Awassa. In addition, the gut microbiota diversity varied significantly across the gut region based on the Chao1, Shannon and Simpson index. The microbiome analyses of all samples in the midgut region showed significantly higher values for alpha diversity (Chao 1, Shannon and Simpson). Beta diversity analysis revealed a clear separation of samples according to sampling areas and gut regions. The most abundant genera were _sensu_stricto and _XI genera across all samples. Between the two sampling lakes, two phyla, Phylum Fusobacteria and Cyanobacteria, were found to be significantly different. On the other hand, six phyla (Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Proteobacteria and Cyanobacteria) were significantly different across gut regions. In this study, we found that all samples shared a large core microbiota, comprising a relatively large number of OTUs, which was dominated by , , Cyanobacteria, Fusobacteria and This study has established the bases for future large-scale investigations of gut microbiota of fishes in Ethiopian lakes.
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http://dx.doi.org/10.3390/microorganisms8071040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7409238PMC
July 2020

Biogenic Amine Contents and Microbial Characteristics of Cambodian Fermented Foods.

Foods 2020 Feb 15;9(2). Epub 2020 Feb 15.

Institute of Food Science, Department of Food Science and Technology, BOKU - University of Natural Resources and Life Sciences Vienna, Muthgasse 18, A-1190 Vienna, Austria.

Naturally fermented foods are an important part of the typical diet in Cambodia. However, the food safety status of these products has not been widely studied. The aim of this study was, therefore, to provide an overview of the quality of these foods in relation to microbiology and biogenic amines. Additionally, the obtained results were compared to the habits and practices of Cambodians in handling this type of food. A total of 57 fermented foods (42 fishery and 15 vegetable products) were collected from different retail markets in the capital of Cambodia. Pathogenic spp., spp., and were not detected in 25 g samples. Generally, less than 10 cfu/g of , , spp., Enterobacteriaceae, and molds were present in the fermented foods. group members (<10 to 2.3 × 10 cfu/g), lactic acid bacteria (<10 to 1.1 × 10 cfu/g), halophilic and halotolerant bacteria (<10 to 8.9 × 10 cfu/g), sulfite-reducing spp. (<10 to 3.5 × 10 cfu/g), and yeasts (<10 to 1.1 × 10 cfu/g) were detected in this study. Still, the presence of pathogenic and spoilage microorganisms in these fermented foods was within the acceptable ranges. Putrescine, cadaverine, tyramine, and histamine were detected in 100%, 89%, 81%, and 75% of the tested products, respectively. The concentrations of histamine (>500 ppm) and tyramine (>600 ppm) were higher than the recommended maximum levels in respectively four and one of 57 fermented foods, which represents a potential health risk. The results suggest that the production process, distribution, and domestic handling of fermented foods should be re-evaluated. Further research is needed for the establishment of applicable preservation techniques in Cambodia.
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http://dx.doi.org/10.3390/foods9020198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7074300PMC
February 2020

Bacterial growth dynamics and corresponding metabolite levels in the extraction area of an Austrian sugar beet factory using antimicrobial treatment.

J Sci Food Agric 2020 Apr 11;100(6):2713-2721. Epub 2020 Feb 11.

Department of Food Science and Technology, Institute of Food Science, BOKU - University of Natural Resources and Life Sciences Vienna, Vienna, Austria.

Background: During the manufacture of sucrose from sugar beet, different microorganisms originating from the plant material as well as from the soil enter the process. Due to the formation of polysaccharide-based slimes, these contaminants may induce several adverse effects such as filtration problems during juice purification. Certain microorganisms also metabolize sucrose, leading to product losses with financial consequences. To better understand and to prevent these negative effects, the aim of the study was to investigate the evolution of relevant bacterial groups, including their metabolites appearing during the extraction process. For this purpose, one production cycle was monitored to identify the major contamination steps and to clarify how they relate to the processing conditions. Traditionally, different antimicrobial agents such as formaldehyde, sulfur dioxide, hypochlorous acid, sodium hypochlorite, and chlorine dioxide have been added to inhibit microbial growth. In the present study, a rosin-based product derived from pine trees was applied as an alternative to those substances.

Results: Press water, raw juice, and mid-tower juice were identified as being highly contaminated with bacteria, and processing conditions such as time, temperature and pH level significantly influenced bacterial levels and the corresponding metabolites. Among the contaminants identified, lactic acid bacteria, and mesophilic and thermophilic aerobic bacteria played a dominant role, whereas lactic acid, acetic acid, butyric acid, and ethanol were identified as typical metabolites.

Conclusion: Bacterial growth during production could be reduced by shock dosing of the rosin-based material in the extraction area. © 2020 Society of Chemical Industry.
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http://dx.doi.org/10.1002/jsfa.10303DOI Listing
April 2020

Lactic Acid Bacteria Isolation from Spontaneous Sourdough and Their Characterization Including Antimicrobial and Antifungal Properties Evaluation.

Microorganisms 2019 Dec 30;8(1). Epub 2019 Dec 30.

REQUIMTE-Rede de Química e Tecnologia, Laboratório de Química Verde (LAQV), Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto (FCUP), Rua do Campo Alegre, s/n. P-4169-007 Porto, Portugal.

This research effort aimed at isolating and phenotypically characterizing lactic acid bacteria (LAB) isolates from a spontaneous rye sourdough manufactured following traditional protocols, as well as at evaluating their antimicrobial and antifungal properties as key features for future industrial applications. Thirteen LAB strains of potential industrial interest were isolated and identified to species-level via PCR. Most of the sourdough isolates showed versatile carbohydrate metabolisms. The No. 242 and No. 173 demonstrated to be gas producers; thus, revealing their heterofermenter or facultative homofermenter features. Viable counts higher than 7.0 log (CFU/mL) were observed for No. 244, No. 210, No. 173, No. 206, No. 183, No. 245 and No. 135 strains, after exposure at pH 2.5 for 2 h. Moreover, No. 122, No. 210, No. 51, No. 244, and No. 71 showed growth inhibition properties against all the tested fifteen pathogenic strains. Finally, all LAB isolates showed antifungal activities against , , and . These results unveiled the exceptionality of spontaneous sourdough as a source of LAB with effective potential to be considered in the design of novel commercial microbial single/mixed starter cultures, intended for application in a wide range of agri-food industries, where the antimicrobial and antifungal properties are often sought and necessary. In addition, metabolites therefrom may also be considered as important functional and bioactive compounds with high potential to be employed in food and feed, as well as cosmetic and pharmaceutical applications.
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http://dx.doi.org/10.3390/microorganisms8010064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7023352PMC
December 2019

The Influence of Meat Batter Composition and Sausage
Diameter on Microbiota and Sensory Traits of Artisanal
Wild Boar Meat Sausages.

Food Technol Biotechnol 2019 Sep;57(3):378-387

Department of Microbiology, University of Zagreb Faculty of Agriculture, Svetošimunska 25, 10000 Zagreb, Croatia.

In this study, the influence of meat batter composition and sausage diameter on the development of microbiota and sensory traits of traditional, spontaneously fermented wild boar meat sausages are evaluated. This research also demonstrates how principal component analysis (PCA) can be used to relate product sensory properties to particular microbial genotype and to select potential starter or adjunct culture. Generally, similar microbiological results were obtained in all types of products. The undesirable microbiota was either not detected at any sausage production stage or its number decreased below the detection limit in ripened sausages. The low growth rate of lactic acid bacteria (LAB) was consistent with the obtained pH and slow acidification rate. Although no differences in the composition of LAB species were noticed between sausage types (50S=50% wild boar meat in small casing, 50L=50% wild boar meat in large casing, 100S=100% wild boar meat in small casing), a clear separation based on LAB genotypes could be observed. Upon quantitative descriptive analysis, significant differences in sensory attributes between sausage types were established. According to the PCA, the overall acceptability traits of sausages are closely linked to one genotype (LM_4). Of all tested technological properties, LM_4 strains showed remarkable acidification ability, lowering the pH from pH=5.41 to 3.74, and pronounced proteolytic activity on skimmed milk as well as antagonistic activity against (DSM 20231) and (LMG 17208). Lipolytic and haemolytic activities were not detected, and all analyzed strains were susceptible to tested antibiotics and possessed no biogenic amine genes.
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http://dx.doi.org/10.17113/ftb.57.03.19.6197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6902292PMC
September 2019

Identification, Classification and Screening for γ-Amino-butyric Acid Production in Lactic Acid Bacteria from Cambodian Fermented Foods.

Biomolecules 2019 11 22;9(12). Epub 2019 Nov 22.

Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 18, A-1190 Vienna, Austria.

Screening for various types of lactic acid bacteria (LAB) that form the biological agent γ-amino-butyric acid (GABA) is important to produce different kinds of GABA-containing fermented foods. So far, no GABA-producing LAB have been reported from Cambodian fermented foods. Most small-scale fermentations and even some industrial processes in this country still rely on indigenous LAB. The application of GABA-producing autochthonous starters would allow the production of Cambodian fermented foods with an additional nutritional value that meet the population's dietary habits and that are also more attractive for the international food market. Matrix-assisted laser desorption/ionizing time-of-flight mass spectrometry (MALDI-TOF MS) and partial 16S rDNA sequencing were used to identify 68 LAB isolates from Cambodian fermented foods. These isolates were classified and grouped with (GTG) rep-PCR, resulting in 50 strains. Subsequently, all strains were investigated for their ability to produce GABA by thin layer chromatography. GABA-positive strains were further analyzed by the GABase assay. Of the six GABA-positive LAB strains-one , two , and three strains-two strains produced high amounts of GABA (20.34 mM, 16.47 mM). These strains should be further investigated for their potential application as GABA-producing starter cultures in the food applications.
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http://dx.doi.org/10.3390/biom9120768DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6995518PMC
November 2019

Whole Genome Sequencing-Based Comparison of Food Isolates of .

Front Microbiol 2019 2;10:1464. Epub 2019 Jul 2.

Department of Nanobiotechnology, Institute for Biologically Inspired Materials, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria.

is an emerging foodborne pathogen, which is linked to life-threatening infections causing septicemia, meningitis, and necrotizing enterocolitis. These infections have been epidemiologically connected to ingestion of contaminated reconstituted powder infant formula. Even at low water activity can survive for a long time; it is capable of protective biofilm formation and occasionally shows high virulence and pathogenicity even following stressful environmental conditions. Hence it is a challenging task for the food industry to control contamination of food ingredients and products through the entire production chain, since an increasing number of severe food-related outbreaks of infections has been observed. The seemingly great capability of to survive even strict countermeasures combined with its prevalence in many food ingredients requires a greater in depth understanding of its virulence factors to master the food safety issues related to this organism. In this context, we present the whole genome sequence (WGS) of two different isolated from skimmed milk powder (C7) and ready-to-eat salad mix (C8), respectively. These are compared to other, already sequenced, genomes. Sequencing of the allele revealed that both isolates were . We investigated the molecular characteristics of both isolates relevant for genes associated with pathogenesis and virulence factors, resistance to stressful environmental conditions (e.g., osmotic and heat), survival in desiccation as well as conducted a comparative genomic analysis. By using multi-locus sequence typing (MLST), the genetic type of both isolates is assessed and the number of unique genes is determined. DNA of C8 is shown to hold a novel and unique sequence type; the number of unique genes identified in the genomic sequence of C7 and C8 were 109 and 188, respectively. Some of the determined unique genes such as the and genes are linked to the Type VI Secretion System cluster, which is associated with pathogenicity and virulence factors. Moreover, seven genes encoding for multi-drug resistance were found in both isolates. The finding of a number of genes linked to producing capsules and biofilm are likely related to the observed resistance to desiccation.
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http://dx.doi.org/10.3389/fmicb.2019.01464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6615433PMC
July 2019

Characterization of Biofilm Formation by Cronobacter spp. Isolates of Different Food Origin under Model Conditions.

J Food Prot 2019 01;82(1):65-77

1 Department of Food Science and Technology, Institute of Food Science, University of Natural Resources and Life Sciences, A-1190 Vienna, Austria.

Cronobacter spp. are opportunistic human pathogens that cause serious diseases in neonates and immunocompromised people. Owing to their biofilm formation on various surfaces, both their detection and their removal from production plants constitute a major challenge. In this study, food samples were randomly collected in Austria and examined for the presence of Cronobacter spp. Presumptive isolates were identified by a polyphasic approach. Five percent of the samples were positive for C. sakazakii and 2.4% for C. dublinensis. Individual growth of the isolates was characterized based on lag time, growth rate, and generation time. During an incubation period of 6 to 72 h, biofilm formation of 11 selected isolates was quantified under model conditions by a crystal violet staining assay with 96-well plates with different carbon sources (lactose, glucose, maltose, sucrose, and sodium acetate) and NaCl levels and under variable temperature and pH conditions. Biofilm formation was more pronounced at lactose concentrations between 0.25 and 3% compared with 5% lactose, which lead to thinner layers. C. sakazakii isolate C7, isolated from infant milk powder, was the strongest biofilm producer at 10 mM Mg and 5 mM Mn, 0.5% sodium acetate, at pH levels between 7 and 9 at 37°C for 24 h. C. sakazakii strain C6 isolated from a plant air filter was identified as a moderate biofilm former and C. sakazakii strain DSM 4485, a clinical isolate, as a weak biofilm former. Based on PCR detection, genes bcsA, bcsB, and bcsG encoding for cellulose could be identified as markers for biofilm formation. Isolates carrying bcsA and bcsB showed significantly stronger biofilm formation than isolates without these genes ( P < 0.05), in strong correlation with the results obtained in the crystal violet assay. Further investigations using confocal laser scanning microscopy revealed that extracellular polymeric substances and glycocalyx secretions were the dominating components of the biofilms and that the viable fraction of bacteria in the biofilm decreased over time.
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http://dx.doi.org/10.4315/0362-028X.JFP-18-036DOI Listing
January 2019

Prevalence of antibiotic-resistant E. coli in broilers challenged with a multi-resistant E. coli strain and received ampicillin, an organic acid-based feed additive or a synbiotic preparation.

Poult Sci 2019 Jun;98(6):2598-2607

Department of Food Science and Technology, Institute of Food Science, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria.

The aim of this study was to evaluate the effect of ampicillin, an organic acid-based feed additive and a synbiotic preparation on the prevalence of antibiotic-resistant E. coli in the ceca of broilers. A total of 2000 broiler chickens (Ross 708) were randomly assigned to 5 groups with 8 replicates. The negative control group was the only group that was not subjected to avian pathogenic E. coli challenge, while all the other 4 groups received a multi-resistant E. coli strain that was resistant to ampicillin, cephalexin, and nalidixic acid as an oral challenge. The second group served as a challenge control, and the third group received the antibiotic ampicillin via water for 5 d. The fourth group received a feed additive based on organic acids and cinnamaldehyde, and the fifth group received a synbiotic preparation via feed and water. On day 17 and 38 of the trial, cecal samples from 3 birds from each of the 40 pens were obtained, and the E. coli counts and abundances of antibiotic-resistant E. coli were determined. Oral challenge with an avian pathogenic E. coli strain did not influence the performance, and there was no significant difference in growth performance between groups. The total E. coli count was lower (P < 0.05) in the group supplemented with the synbiotic than in the challenge control group on day 38 of the trial. Administration of an antibiotic for 5 d led to a significant increase in the abundance of E. coli strains resistant to ampicillin, amoxicillin-clavulanic acid, cefoxitin, and ceftriaxone. There was no increase in the abundance of antibiotic-resistant E. coli observed in the groups that received feed supplemented with an organic acid/cinnamaldehyde-based feed additive or a synbiotic. Moreover, the effects of the tested feed additives on the prevalence of resistant E. coli are demonstrated by the lower ceftriaxone minimal inhibitory concentration values for this group than for the antibiotic group. Additionally, the synbiotic group exhibited lower ceftriaxone minimal inhibitory concentration values than the antibiotic group.
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http://dx.doi.org/10.3382/ps/pez004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527514PMC
June 2019

Fermentability of a Novel Galacto-Oligosaccharide Mixture by spp. and spp.

Molecules 2018 Dec 18;23(12). Epub 2018 Dec 18.

Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences Vienna, A-1190 Vienna, Austria.

This study aimed to investigate the specific growth stimulation of certain desired intestinal bacteria by a novel galacto-oligosaccharide mixture, which was produced with a β-galactosidase from a potential probiotic isolate that contained mainly oligosaccharides of β-1,3 and β-1,6 glycosidic linkages (termed Lb-GOS) using single-strain fermentations. The composition of this Lb-GOS mixture was 33.5% disaccharides, 60.5% trisaccharides, 4.8% tetrasaccharides, and 1.0% pentasaccharides with a negligible amount of monosaccharides, lactose, and lactobionic acid (0.3%). Eight spp. strains and three spp. strains were used in single-strain fermentations to determine the fermentation activity scores of this Lb-GOS preparation compared to two commercially available prebiotic mixtures, 4'GOS-P and Vivinal GOS (V-GOS). The highest scores were obtained when Lb46 and the two strains, subsp. Bif1 and Bif3, were grown on these galacto-oligosaccharide mixtures. In addition, the Lb-GOS mixture was found to have higher fermentation activity scores; hence, it stimulated the growth of these probiotic strains more than 4'GOS-P and V-GOS, which may be attributed to the different glycosidic linkage types that are found in the Lb-GOS mixture compared to the other two commercial preparations. These findings suggested that the Lb-GOS mixture that is described in this work should be of interest for the formulations of new carbohydrate-based functional food ingredients.
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http://dx.doi.org/10.3390/molecules23123352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6321129PMC
December 2018

Assessment of Microbial Community Dynamics in River Bank Filtrate Using High-Throughput Sequencing and Flow Cytometry.

Front Microbiol 2018 29;9:2887. Epub 2018 Nov 29.

Laboratory of Microbiology, Institute of Sanitary Engineering and Water Pollution Control (SIG), Department of Water, Atmosphere and Environment, University of Natural Resources and Life Sciences, Vienna, Austria.

Surface-groundwater interactions play an important role in microbial community compositions of river bank filtrates. Surface water contaminations deriving from environmental influences are attenuated by biogeochemical processes in the hyporheic zone, which are essential for providing clean and high-quality drinking water in abstraction wells. Characterizing the flow regime of surface water into the groundwater body can provide substantial information on water quality, but complex hydraulic dynamics make predictions difficult. Thus, a bottom up approach using microbial community shifting patterns as an overall outcome of dynamic water characteristics could provide more detailed information on the influences that affect groundwater quality. The combination of high-throughput sequencing data together with flow cytometric measurements of total cell counts reveals absolute abundances among taxa, thus enhancing interpretation of bacterial dynamics. 16S rRNA high-throughput sequencing of 55 samples among six wells in a well field in Austria that is influenced by river bank filtrate within a time period of 3 months has revealed both, clear differences as well as strong similarity in microbiome compositions between wells and dates. A significant community shift from April to May occurred in four of six wells, suggesting that surface water flow regimes do affect these wells stronger than others. Triplicate sampling and subsequent sequencing of wells at different dates proved the method to be reproducible. Flow cytometric measurements of total cells indicate microbial shifts due to increased cell counts and emphasize the rise of allochthonous microorganisms. Typical freshwater bacterial lineages (Verrucomicrobia, Bacteroidetes, Actinobacteria, Cyanobacteria, Armatimonadetes) were identified as most increasing phyla during community shifts. The changes are most likely a result of increased water abstraction in the wells together with constant river water levels rather than rain events. The results provide important knowledge for future implementations of well utilization in dependency of the nearby Danube River water levels and can help drawing conclusions about the influence of surface water in the groundwater such that hygienically save and clean drinking water with a stable microbial community can be provided.
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http://dx.doi.org/10.3389/fmicb.2018.02887DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6281747PMC
November 2018

The application of antibiotics in broiler production and the resulting antibiotic resistance in Escherichia coli: A global overview.

Poult Sci 2019 Apr;98(4):1791-1804

Department of Food Science and Technology, Institute of Food Science, BOKU-University of Natural Resources and Life Sciences, 1190 Vienna, Austria.

The increase in antibiotic resistance is a global concern for human and animal health. Resistant microorganisms can spread between food-producing animals and humans. The objective of this review was to identify the type and amount of antibiotics used in poultry production and the level of antibiotic resistance in Escherichia coli isolated from broilers. Isolate information was obtained from national monitoring programs and research studies conducted in large poultry-producing regions: US, China, Brazil, and countries of EU-Poland, United Kingdom, Germany, France, and Spain. The survey results clearly display the absence of a harmonized approach in the monitoring of antibiotics per animal species and the evaluation of resistances using the same methodology. There is no public long-term quantitative data available targeting the amount of antibiotics used in poultry, with the exception of France. Data on antibiotic-resistant E. coli are available for most regions but detection of resistance and number of isolates in each study differs among regions; therefore, statistical evaluation was not possible. Data from France indicate that the decreased use of tetracyclines leads to a reduction in the detected resistance rates. The fluoroquinolones, third-generation cephalosporins, macrolides, and polymyxins ("highest priority critically important" antibiotics for human medicine according to WHO) are approved for use in large poultry-producing regions, with the exception of fluoroquinolones in the US and cephalosporins in the EU. The approval of cephalosporins in China could not be evaluated. Tetracyclines, aminoglycosides, sulfonamides, and penicillins are registered for use in poultry in all evaluated countries. The average resistance rates in E. coli to representatives of these antibiotic classes are higher than 40% in all countries, with the exception of ampicillin in the US. The resistance rates to fluoroquinolones and quinolones in the US, where fluoroquinolones are not registered for use, are below 5%, while the average of resistant E. coli is above 40% in Brazil, China, and EU, where use of fluoroquinolones is legalized. However, banning of fluoroquinolones and quinolones has not totally eliminated the occurrence of resistant populations.
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http://dx.doi.org/10.3382/ps/pey539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6414035PMC
April 2019

Applicability of Yeast Fermentation to Reduce Fructans and Other FODMAPs.

Nutrients 2018 Sep 6;10(9). Epub 2018 Sep 6.

Department of Food Science and Technology, University of Natural Resources and Life Sciences (BOKU), 1190 Vienna, Austria.

A diet low in fermentable oligosaccharides, disaccharides, monosaccharides and, polyols (FODMAPs) is recommended for people affected by irritable bowel syndrome (IBS) and non-coeliac wheat sensitivity (NCWS) in order to reduce symptoms. Therefore, the aim of this study was to evaluate the impact of 13 sourdough-related yeasts on FODMAP degradation, especially fructans. First, a model system containing a typical wheat carbohydrate profile was applied to evaluate the growth rate of each yeast strain. Additionally, changes in the sugar composition, for up to four days, were monitored by high-pressure anion-exchange chromatography (HPAEC). A more realistic approach with a wheat flour suspension was used to characterize CO₂ production according to the Einhorn method. The reduction of the total fructans was analyzed using an enzymatic method. Furthermore, a fingerprint of the present fructans with different degrees of polymerization was analyzed by HPAEC. The results revealed strong differences in the examined yeast strains' ability to degrade fructans, in both the model system and wheat flour. Overall, isolated from Austrian traditional sourdough showed the highest degree of degradation of the total fructan content and the highest gas building capacity, followed by . Hence, this study provides novel knowledge about the FODMAP conversion of yeast strains.
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http://dx.doi.org/10.3390/nu10091247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6163668PMC
September 2018

Immunogold Nanoparticles for Rapid Plasmonic Detection of .

Sensors (Basel) 2018 Jun 25;18(7). Epub 2018 Jun 25.

Department of Nanobiotechnology, Institute for Biologically Inspired Materials, BOKU-University of Natural Resources and Life Sciences, Vienna, Vienna A-1190, Austria.

is a foodborne pathogen that can cause a rare, septicemia, life-threatening meningitis, and necrotizing enterocolitis in infants. In general, standard methods for pathogen detection rely on culture, plating, colony counting and polymerase chain reaction DNA-sequencing for identification, which are time, equipment and skill demanding. Recently, nanoparticle- and surface-based immunoassays have increasingly been explored for pathogen detection. We investigate the functionalization of gold nanoparticles optimized for irreversible and specific binding to and their use for spectroscopic detection of the pathogen. We demonstrate how 40-nm gold nanoparticles grafted with a poly(ethylene glycol) brush and functionalized with polyclonal antibodies raised against can be used to specifically target . The strong extinction peak of the Au nanoparticle plasmon polariton resonance in the optical range is used as a label for detection of the pathogens. Individual binding of the nanoparticles to the surface is also verified by transmission electron microscopy. We show that a high degree of surface functionalization with anti- optimizes the detection and leads to a detection limit as low as 10 CFU/mL within 2 h using a simple cuvette-based UV-Vis spectrometric readout that has great potential for further optimization.
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http://dx.doi.org/10.3390/s18072028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068645PMC
June 2018

Effects of selected lactobacilli on the functional properties and stability of gluten-free sourdough bread.

Eur Food Res Technol 2018 13;244(6):1037-1046. Epub 2017 Dec 13.

1Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria.

The aim of this investigation was to determine the influence of seven different spp. (Lb.) strains compared with a commercial starter culture (CS) on the functional properties of gluten-free (GF) sourdough-breads. The sourdough stability of selected strains was also evaluated upon back-slopping. Results showed that the bread properties were greatly affected by the Lb. strains. Millet breads achieved lower specific volumes (1.80-2.19 cm/g), higher crumb firmness (19.01-42.19 N) and lower relative elasticities (21.5-43.4%) than buckwheat breads. Compared with the CS, and positively influenced the crumb firmness of buckwheat and millet breads, respectively, while enhanced this property in both breads. Only one of the two strains was able to improve all functional properties in both GF breads. Back-slopping of the sourdoughs revealed stable properties in case of buckwheat, while maturity of the millet sourdough could not be reached. These observations were supported by the microbial count, metabolite production and carbohydrate consumption. Mature sourdough significantly improved the crumb firmness and porosity of the GF breads. These results highlighted the importance of selecting the appropriate lactic acid bacteria strains, to maximize the quality of GF bread.
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http://dx.doi.org/10.1007/s00217-017-3020-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6448362PMC
December 2017

Influence of Orally Administered Probiotic Strains on Vaginal Microbiota in Women with Breast Cancer during Chemotherapy: A Randomized Placebo-Controlled Double-Blinded Pilot Study.

Breast Care (Basel) 2017 Oct 27;12(5):335-339. Epub 2017 Oct 27.

Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria.

Background: Due to chemotherapy and estrogen deprivation therapy, genitourinary syndrome of menopause is a common condition in breast cancer patients. We aimed to determine the effect of an orally administered preparation on the vaginal microbiota in breast cancer patients.

Methods: Postmenopausal breast cancer patients receiving chemotherapy, with vaginal atrophy and an intermediate vaginal microbiota (Nugent score 4-6), were either randomized to the intervention group receiving probiotic capsules of 4 species or to the control group receiving placebo twice daily for 2 weeks. Consecutive vaginal swabs were taken at baseline, 1 day after administration of the last capsule (follow-up 1), and after 1 week (follow-up 2) in 22 patients (11 vs. 11).

Results: We observed a positive influence on the vaginal microbiota in 7/11 (63%) women in the intervention group, and 4/11 (36%) women in the control group. There was a shift in Nugent score towards normal microbiota levels in the intervention group (-1.3 at follow-up 1, -0.45 at follow-up 2) and a significant deterioration of the Nugent score in the control group (+0.4 at follow-up 1, +2.5 at follow-up 2).

Conclusion: The orally administered preparation has the potential to improve the vaginal microbiota in women undergoing chemotherapy for breast cancer.
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http://dx.doi.org/10.1159/000478994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5704692PMC
October 2017

Effect of an organic acids based feed additive and enrofloxacin on the prevalence of antibiotic-resistant E. coli in cecum of broilers.

Poult Sci 2017 Sep;96(11):4053-4060

Department of Food Science and Technology, Institute of Food Science, BOKU - University of Natural Resources and Life Sciences, Vienna, Austria.

Increasing antibiotic resistance is a major public health concern. Fluoroquinolones are used to treat and prevent poultry diseases worldwide. Fluoroquinolone resistance rates are high in their countries of use. The aim of this study was to evaluate the effect of an acids-based feed additive, as well as fluoroquinolone antibiotics, on the prevalence of antibiotic-resistant E. coli. A total of 480 broiler chickens (Ross 308) were randomly assigned to 3 treatments: a control group receiving a basal diet; a group receiving a feed additive (FA) based on formic acid, acetic acid and propionic acid; and an antibiotic enrofloxacin (AB) group given the same diet, but supplemented with enrofloxacin in water. A pooled fecal sample of one-day-old chicks was collected upon arrival at the experimental farm. On d 17 and d 38 of the trial, cecal samples from each of the 8 pens were taken, and the count of E. coli and antibiotic-resistant E. coli was determined.The results of the present study show a high prevalence of antibiotic-resistant E. coli in one-day-old chicks. Supplementation of the diet with FA and treatment of broilers with AB did not have a significant influence on the total number of E. coli in the cecal content on d 17 and d 38 of the trial. Supplementation with FA contributed to better growth performance and to a significant decrease (P ≤ 0.05) in E. coli resistant to ampicillin and tetracycline compared to the control and AB groups, as well as to a decrease (P ≤ 0.05) in sulfamethoxazole and ciprofloxacin-resistant E. coli compared to the AB group. Treatment with AB increased (P ≤ 0.05) the average daily weight compared to the control group and increased (P ≤ 0.05) the number of E. coli resistant to ciprofloxacin, streptomycin, sulfamethoxazole and tetracycline; it also decreased (P ≤ 0.05) the number of E. coli resistant to cefotaxime and extended spectrum beta-lactamase- (ESBL-) producing E. coli in the ceca of broilers.
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http://dx.doi.org/10.3382/ps/pex232DOI Listing
September 2017

Lactococci of Local Origin as Potential Starter Cultures
for Traditional Montenegrin Cheese Production.

Food Technol Biotechnol 2017 Mar;55(1):55-66

BOKU - University of Natural Resources and Life Sciences, Department of Food Science and Technology, Muthgasse 18, AT-1190 Vienna, Austria.

The aim of this study is to characterise and examine the biochemical properties of 40 strains isolated from indigenous Montenegrin dairy products in order to explore their potential to be used as starter cultures for producing typical Montenegrin cheese, such as 'bijeli sir', 'masni sir' and 'njeguški sir'. Their safety regarding the production of biogenic amines, the presence of antimicrobial resistance and the antibacterial activity against relevant pathogens and spoilage microorganisms has also been tested. Based on the characterisation, all strains belong to ssp. . Out of these 40 strains, 23 displayed rapid acidification ability and proteolysis. However, none of the strains exhibited the ability of lipid degradation. Most of the strains were not associated with any health risk investigated. Summing up, a large percentage (27.5%) of the tested strains showed good properties. These strains should be further examined for their possible application as specific starter cultures in the production of indigenous cheese in Montenegro.
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http://dx.doi.org/10.17113/ftb.55.01.17.4854DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434366PMC
March 2017

Tetracycline Resistance Patterns of Lactobacillus buchneri Group Strains.

J Food Prot 2016 10;79(10):1741-1747

BOKU-University of Natural Resources and Life Sciences, Vienna, Department of Food Science and Technology, Institute of Food Science, Muthgasse 18, A-1190 Vienna, Austria.

Lactobacilli are applied as starter cultures for controlled fermentation in the production of food and feed. Among other lactobacilli, members of the Lactobacillus buchneri group are used in fermented milk, wine, and silage. Most of the L. buchneri species used for the manufacturing of food or feed are already on the list for qualified presumption of safety status and are recommended as biological agents by the European Food Safety Authority. Consequently, new strains intended as food or feed additives do not require any additional safety check than confirming the absence of transferable antibiotic resistance determinants. Of these determinants, tetracycline resistance genes are especially predominant in lactobacilli. Within this study, a total of 128 strains belonging to the L. buchneri group ( L. buchneri , L. diolivorans , L. farraginis , L. hilgardii , L. kefiri , L. kisonensis , L. otakiensis , L. parabuchneri , L. parafarraginis , L. parakefiri , L. rapi , L. senioris , and L. sunkii ) were examined for their susceptibility to tetracycline. Tetracycline MICs were assessed by the broth microdilution method according to ISO 10932/IDF 223. Subsequently, the presence of tetracycline resistance genes was investigated by using PCR. In addition, selected strains were tested for a broader range of tetracycline resistance genes by using a microarray technique. Applying the tetracycline cutoff values defined by European Food Safety Authority for heterofermentative and obligately homofermentative lactobacilli, 96.9% of the strains would have been categorized as tetracycline resistant. However, none of the tested tetracycline resistance genes could be detected by PCR or microarray analysis. Furthermore, the MIC distribution of all strains was unimodal and at the high end of the tested tetracycline concentration range (4 to 256 μg/ml). Thus, these data suggest that tetracycline resistance in the L. buchneri group strains is intrinsic, which complies with the requirements defined in the qualified presumption of safety outline.
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http://dx.doi.org/10.4315/0362-028X.JFP-15-577DOI Listing
October 2016

The intestinal microbiota of piglets fed with wheat bran variants as characterised by 16S rRNA next-generation amplicon sequencing.

Arch Anim Nutr 2016 ;70(3):173-89

a Institute of Food Science, Department of Food Science and Technology , University of Natural Resources and Life Sciences , Vienna , Austria.

The intestinal microbiota of piglets fed with a Control diet low in dietary fibre and modified wheat bran variants as an additional source of insoluble dietary fibre was characterised. In this context, variances in the microbiota of three different gut segments were assessed. Wheat bran was either included in its native form or modified by fermentation and extrusion before added at 150 g/kg to a basal diet for 48 piglets (12 animals per treatment). Total DNA was extracted from digesta samples from the jejunum, the end of the ileum and the colon ascendens. Samples were prepared accordingly for subsequent sequencing with the Illumina MiSeq. The obtained results revealed distinct location-specific differences in microbial composition. While Firmicutes were most predominant in all three gut segments, Bacteroidetes were additionally found in the colon at high abundance. The parameters of alpha and beta diversity analysis showed significant differences (p < 0.01) between the colon and the other two gut segments. Specialised bacterial groups like Prevotella and Ruminococcaceae were among the most predominant ones found in the colon, as they possess cellulolytic properties to degrade (at least partially) non-starch polysaccharides, while their abundance was negligible in the jejunum and the ileum. Conversely, the genera Lactobacillus, Bifidobacterium and Veillonella, for example, were among the most predominant groups in the jejunum and ileum, while in the colon they were hardly found. Although statistical taxonomical evaluation, following p-value correction, did not reveal pronounced differences in abundance related to bran modification, alpha and beta diversity analysis showed an influence regarding the various feeding strategies applied. Based on these findings, a more in-depth view on intestinal microbial composition within the gastrointestinal tract of young pigs fed with low- and high-fibre diets was generated.
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http://dx.doi.org/10.1080/1745039X.2016.1160534DOI Listing
December 2016

Celeribacter persicus sp. nov., a polycyclic-aromatic-hydrocarbon-degrading bacterium isolated from mangrove soil.

Int J Syst Evol Microbiol 2016 Apr 10;66(4):1875-1880. Epub 2016 Feb 10.

BOKU-University of Natural Resources and Life Sciences, Department of Food Science and Technology, Institute of Food Science, Muthgasse 18, A-1190 Vienna, Austria.

A Gram-stain-negative, mesophilic bacterial strain, designated SBU1T, which degrades polycyclic aromatic hydrocarbons was isolated from the sediments of the mangrove forests of Nayband Bay in the Iranian Persian Gulf during a bioremediation experiment. The 16S rRNA gene sequence of strain SBU1T exhibited highest similarities with Celeribacter indicus P73T (98.52%) and Celeribacter neptunius H 14T (97.05%). Phylogenetic analysis, based on 16S rRNA gene sequences, demonstrated that strain SBU1T fell within a cluster consisting of the type strains of species of the genus Celeribacter and formed a stable clade with C. indicus P73T in trees generated with three algorithms. The fatty acid profile of strain SBU1T consisted of the major fatty acids C18:1ω7c/ω6c and C18:1ω7c 11-methyl. The major compounds in the polar lipid profile were one phosphatidylglycerol and four unidentified phospholipids. The quinone system exclusively comprised ubiquinone (Q-10). The DNA G+C content was 60.4 mol%. A combination of phylogenetic analysis, DNA-DNA hybridization estimation, average nucleotide identity results and differential phenotypic and chemotaxonomic characteristics demonstrated that strain SBU1T could be distinguished from its close relatives. Therefore, strain SBU1T is considered to represent a novel species of the genus Celeribacter for which the name Celeribacter persicus sp. nov. is proposed. The type strain is SBU1T (=MCCC 1A00672T=DSM 100434T).
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http://dx.doi.org/10.1099/ijsem.0.000961DOI Listing
April 2016

Fermented and extruded wheat bran in piglet diets: impact on performance, intestinal morphology, microbial metabolites in chyme and blood lipid radicals.

Arch Anim Nutr 2015 ;69(5):378-98

a Christian Doppler Research Laboratory for Innovative Bran Biorefinery, Department of Food Science and Technology , University of Natural Resources and Life Sciences , Vienna , Austria.

The aim of the present study was to evaluate the influence of native, fermented and extruded wheat bran on the performance and intestinal morphology of piglets. Additionally, short-chain fatty acids (SCFA), biogenic amines, ammonia, lactic acid, pH as well as E. coli and lactic acid bacterial counts were analysed in digesta samples from three gut sections. Furthermore, the antioxidant potential in blood samples was evaluated based on the lipid radicals formed. For this purpose, 48 newly weaned piglets (28 d old) were allocated to one of the four different dietary treatment groups: no wheat bran (Control), native wheat bran, fermented wheat bran as well as extruded wheat bran. Wheat bran variants were included at 150 g/kg into the diets. All diets were mixed to reach the calculated isonitrogenic nutrient contents. Gut tissue and digesta samples were collected from the proximal jejunum, the terminal ileum and the colon ascendens, blood samples directly at slaughter. Although none of the dietary interventions had an impact on performance parameters, the amount of goblet cells in the ileum was increased upon feeding native and extruded wheat bran, compared to fermented bran (p < 0.05). The E. coli counts in colonic chyme were significantly lower (p < 0.05) in the Control group compared to the groups fed with wheat bran. The concentration of SCFA showed differences for minor compounds (p < 0.05), while linear contrast analyses revealed a reduced concentration of total SCFA in the colon following the feeding of modified wheat bran compared to native wheat bran. This may suggest that several compounds are more easily digested already in the ileum, resulting in a reduced nutrient flow into the large intestine and therefore less unexploited digesta is available as substrate for the microorganisms there. Fermentation also resulted in a significant decrease of methylamine in the colon (p < 0.05), while other biogenic amines in the ileum and colon showed no statistically significant differences. The formation of lipid radicals was decreased (p < 0.05) after feeding native wheat bran compared to the Control group. These results suggest that fermentation and extrusion of wheat bran exert some different impact regarding their physiological mode of action.
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http://dx.doi.org/10.1080/1745039X.2015.1075671DOI Listing
May 2016

Phylogenetic diversity and biological activity of culturable Actinobacteria isolated from freshwater fish gut microbiota.

Microbiol Res 2015 Jun 22;175:6-15. Epub 2015 Jan 22.

BOKU - University of Natural Resources and Life Sciences, Department of Food Science and Technology, Institute of Food Science, Muthgasse 18, A-1190 Vienna, Austria.

The diversity of Actinobacteria isolated from the gut microbiota of two freshwater fish species namely Schizothorax zarudnyi and Schizocypris altidorsalis was investigated employing classical cultivation techniques, repetitive sequence-based PCR (rep-PCR), partial and full 16S rDNA sequencing followed by phylogenetic analysis. A total of 277 isolates were cultured by applying three different agar media. Based on rep-PCR profile analysis a subset of 33 strains was selected for further phylogenetic investigations, antimicrobial activity testing and diversity analysis of secondary-metabolite biosynthetic genes. The identification based on 16S rRNA gene sequencing revealed that the isolates belong to eight genera distributed among six families. At the family level, 72% of the 277 isolates belong to the family Streptomycetaceae. Among the non-streptomycetes group, the most dominant group could be allocated to the family of Pseudonocardiaceae followed by the members of Micromonosporaceae. Phylogenetic analysis clearly showed that many of the isolates in the genera Streptomyces, Saccharomonospora, Micromonospora, Nocardiopsis, Arthrobacter, Kocuria, Microbacterium and Agromyces formed a single and distinct cluster with the type strains. Notably, there is no report so far about the occurrence of these Actinobacteria in the microbiota of freshwater fish. Of the 33 isolates, all the strains exhibited antibacterial activity against a set of tested human and fish pathogenic bacteria. Then, to study their associated potential capacity to synthesize diverse bioactive natural products, diversity of genes associated with secondary-metabolite biosynthesis including PKS I, PKS II, NRPS, the enzyme PhzE of the phenazine pathways, the enzyme dTGD of 6-deoxyhexoses glycosylation pathway, the enzyme Halo of halogenation pathway and the enzyme CYP in polyene polyketide biosynthesis were investigated among the isolates. All the strains possess at least two types of the investigated biosynthetic genes, one-fourth of them harbours more than four. This study demonstrates the significant diversity of Actinobacteria in the fish gut microbiota and it's potential to produce biologically active compounds.
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http://dx.doi.org/10.1016/j.micres.2015.01.009DOI Listing
June 2015