Publications by authors named "Balázs Vajna"

31 Publications

Above-ground parts of white grapevine Vitis vinifera cv. Furmint share core members of the fungal microbiome.

Environ Microbiol Rep 2021 May 5. Epub 2021 May 5.

Department of Plant Anatomy, Institute of Biology, Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary.

Grapevine (Vitis vinifera) is a reservoir of fungal endophytes that may affect its growth, health status and grape production. Although there is growing interest in comparing fungal communities of mainly red grape varieties across various factors using only high-throughput sequencing, the small-scale mycobiome variations in geographically close vineyards need further examination. We aimed to characterize the fungal microbiome of the above-ground tissues of V. vinifera cv. Furmint in different plant parts, seasons and sites using culture-dependent and culture-independent methods, and in planta fluorescent microscopic visualization techniques. Samples were collected from four sites of the Tokaj wine region in Mád and two reference sites in Eger, Hungary, across different seasons for 2 years. Fungal endophytes of young and mature leaves, flowers and grape bunches were collected at different phenological stages. Based on each technique, Aureobasidium pullulans, Cladosporium spp. and the complex species Alternaria alternata dominated the community at every site, season and plant organ. We found no significant difference among communities in distinct neighbouring vineyards, nor when compared with the distant reference sites. We can conclude that the different shoot parts of the Furmint grapevines harbour a common core group of fungal community in these regions.
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http://dx.doi.org/10.1111/1758-2229.12950DOI Listing
May 2021

gen. nov., sp. nov. a novel alkaliphilic bacterium of the family .

Int J Syst Evol Microbiol 2019 Jun 18;71(3). Epub 2021 Mar 18.

Department of Microbiology, Faculty of Science, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary.

Three Gram-stain-negative, non-motile, oxidase- and catalase-positive, rod-shaped, black, facultative phototrophic bacterial strains, RG-N-1a, DMA-N-7a and RA-N-9 were isolated from the water sample from Lake Fertő/Neusiedler See (Hungary). Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the strains form a distinct linage within the family and their closest relatives are K13M18 (96.32%) followed by PAMC 27389 (96.25%). The novel bacterial strains prefer alkaline environments and grow optimally at 23-33 °C in the presence of NaCl (1-2 w/v%). Bacteriochlorophyll a was detected. Cells contained exclusively ubiquinone Q-10. The major cellular fatty acids were Cω7, Ciso ω5 C 3-OH and Cωc 11-methyl. The polar lipid profile contains diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified phospholipid and four unidentified lipids. The assembled draft genome of RG-N-1a had 33 contigs with N50 values 315 027 nt, 96× genome coverage, total length of 4 326 551 bp and a DNA G+C content of 64.9%. Genome-based calculations (genome-to-genome distance and DNA G+C percentage) and pairwise amino acid identity (AAI <73.5%) indicate that RG-N-1a represents a novel genus. RG-N-1a (=DSM 108317=NCAIM B.02647) is suggested as the type strain of a novel genus and species in the family , for which the name gen. nov., sp. nov. is proposed.
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http://dx.doi.org/10.1099/ijsem.0.004762DOI Listing
June 2019

Grazing pressure-induced shift in planktonic bacterial communities with the dominance of acIII-A1 actinobacterial lineage in soda pans.

Sci Rep 2020 11 16;10(1):19871. Epub 2020 Nov 16.

Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/C, Budapest, 1117, Hungary.

Astatic soda pans of the Pannonian Steppe are unique environments with respect to their multiple extreme physical and chemical characteristics (high daily water temperature fluctuation, high turbidity, alkaline pH, salinity, polyhumic organic carbon concentration, hypertrophic state and special ionic composition). However, little is known about the seasonal dynamics of the bacterial communities inhabiting these lakes and the role of environmental factors that have the main impact on their structure. Therefore, two soda pans were sampled monthly between April 2013 and July 2014 to reveal changes in the planktonic community. By late spring in both years, a sudden shift in the community structure was observed, the previous algae-associated bacterial communities had collapsed, resulting the highest ratio of Actinobacteria within the bacterioplankton (89%, with the dominance of acIII-A1 lineage) ever reported in the literature. Before these peaks, an extremely high abundance (> 10,000 individuum l) of microcrustaceans (Moina brachiata and Arctodiaptomus spinosus) was observed. OTU-based statistical approaches showed that in addition to algal blooms and water-level fluctuations, zooplankton densities had the strongest effect on the composition of bacterial communities. In these extreme environments, this implies a surprisingly strong, community-shaping top-down role of microcrustacean grazers.
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http://dx.doi.org/10.1038/s41598-020-76822-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7669872PMC
November 2020

Relationships Between Chemical Defenses of Common Toad (Bufo bufo) Tadpoles and Bacterial Community Structure of their Natural Aquatic Habitat.

J Chem Ecol 2020 Jun 28;46(5-6):534-543. Epub 2020 May 28.

Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.

Many organisms synthesize secondary metabolites against natural enemies. However, to which environmental factors the production of these metabolites is adjusted to is poorly investigated in animals, especially so in vertebrates. Bufadienolides are steroidal compounds that are present in a wide range of plants and animals and, if present in large quantities, can provide protection against natural enemies, such as pathogens. In a correlative study involving 16 natural populations we investigated how variation in bufadienolide content of larval common toads (Bufo bufo) is associated with the bacterial community structure of their aquatic environment. We also evaluated pond size, macrovegetation cover, and the abundance of predators, conspecifics and other larval amphibians. We measured toxin content of tadpoles using HPLC-MS and determined the number of bufadienolide compounds (NBC) and the total quantity of bufadienolides (TBQ). AICc-based model selection revealed strong relationships of NBC and TBQ with bacterial community structure of the aquatic habitat as well as with the presence of conspecific tadpoles. The observed relationships may have arisen due to adaptation to local bacterial communities, phenotypic plasticity, differential biotransformation of toxin compounds by different bacterial communities, or a combination of these processes. Bacterial groups that contribute to among-population variation in toxin content remain to be pinpointed, but our study suggesting that toxin production may be influenced by the bacterial community of the environment represents an important step towards understanding the ecological and evolutionary processes leading to microbiota-mediated variation in skin toxin profiles of aquatic vertebrates.
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http://dx.doi.org/10.1007/s10886-020-01184-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7332479PMC
June 2020

Whole genome sequence analysis of Cupriavidus campinensis S14E4C, a heavy metal resistant bacterium.

Mol Biol Rep 2020 May 13;47(5):3973-3985. Epub 2020 May 13.

Department of Microbiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary.

Cupriavidus sp. are model organisms for heavy metal(loid) resistance and aromatic compound's degradation studies and these characteristics make them a perfect candidate for biotechnological purposes. Bacterial strain S14E4C (identified as Cupriavidus campinensis) was isolated from a playground by enrichment method in a 0.25 mM containing medium. The analysis revealed that this bacterium is able to tolerate high concentrations of heavy metal(loid)s: Cd up to 19.5 mM, Pb to 9 mM, Hg to 5.5 mM and As to 2 mM in heavy metal(loid) salt containing nutrient medium. The whole genome data and analysis of the type strain of C. campinensis CCUG:44526 have not been available so far, thus here we present the genome sequencing results of strain S14E4C of the same species. Analysis was carried out to identify possible mechanisms for the heavy metal resistance and to map the genetic data of C. campinensis. The annotation pipelines revealed that the total genome of strain S14E4C is 6,375,175 bp length with a GC content of 66.3% and contains 2 plasmids with 295,460 bp (GC content 59.9%) and 50,483 bp (GC content 63%). In total 4460 coding sequences were assigned to known functions and 1508 to hypothetical proteins. Analysis proved that strain S14E4C is having gene clusters such as czc, mer, cus, chr, ars to encode various heavy metal resistance mechanisms that play an important role to survive in extreme environments.
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http://dx.doi.org/10.1007/s11033-020-05490-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7239810PMC
May 2020

Bacterial-fungal interactions: ecology, mechanisms and challenges.

FEMS Microbiol Rev 2018 05;42(3):335-352

Helmholtz Centre for Environmental Research-UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318 Leipzig, Germany.

Fungi and bacteria are found living together in a wide variety of environments. Their interactions are significant drivers of many ecosystem functions and are important for the health of plants and animals. A large number of fungal and bacterial families engage in complex interactions that lead to critical behavioural shifts of the microorganisms ranging from mutualism to antagonism. The importance of bacterial-fungal interactions (BFI) in environmental science, medicine and biotechnology has led to the emergence of a dynamic and multidisciplinary research field that combines highly diverse approaches including molecular biology, genomics, geochemistry, chemical and microbial ecology, biophysics and ecological modelling. In this review, we discuss recent advances that underscore the roles of BFI across relevant habitats and ecosystems. A particular focus is placed on the understanding of BFI within complex microbial communities and in regard of the metaorganism concept. We also discuss recent discoveries that clarify the (molecular) mechanisms involved in bacterial-fungal relationships, and the contribution of new technologies to decipher generic principles of BFI in terms of physical associations and molecular dialogues. Finally, we discuss future directions for research in order to stimulate synergy within the BFI research area and to resolve outstanding questions.
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http://dx.doi.org/10.1093/femsre/fuy008DOI Listing
May 2018

Differences in planktonic microbial communities associated with three types of macrophyte stands in a shallow lake.

FEMS Microbiol Ecol 2018 02;94(2)

Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/c., H-1117 Budapest, Hungary.

Little is known about how various substances from living and decomposing aquatic macrophytes affect the horizontal patterns of planktonic bacterial communities. Study sites were located within Lake Kolon, which is a freshwater marsh and can be characterised by open-water sites and small ponds with different macrovegetation (Phragmites australis, Nymphea alba and Utricularia vulgaris). Our aim was to reveal the impact of these macrophytes on the composition of the planktonic microbial communities using comparative analysis of environmental parameters, microscopy and pyrosequencing data. Bacterial 16S rRNA gene sequences were dominated by members of phyla Proteobacteria (36%-72%), Bacteroidetes (12%-33%) and Actinobacteria (5%-26%), but in the anoxic sample the ratio of Chlorobi (54%) was also remarkable. In the phytoplankton community, Cryptomonas sp., Dinobryon divergens, Euglena acus and chrysoflagellates had the highest proportion. Despite the similarities in most of the measured environmental parameters, the inner ponds had different bacterial and algal communities, suggesting that the presence and quality of macrophytes directly and indirectly controlled the composition of microbial plankton.
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http://dx.doi.org/10.1093/femsec/fix164DOI Listing
February 2018

Quantification and handling of nonlinearity in Raman micro-spectrometry of pharmaceuticals.

J Pharm Biomed Anal 2016 Sep 21;128:236-246. Epub 2016 May 21.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111 Budapest, Budafoki út 8, Hungary. Electronic address:

This work demonstrates how nonlinearity in Raman spectrometry of pharmaceuticals can be handled and accurate quantification can be achieved by applying certain chemometric methods including variable selection. Such approach proved to be successful even if the component spectra are very similar or spectral intensities of the constituents are strongly different. The relevant examples are: blends of two crystalline forms of carvedilol ("CRYST-PM" blend) and a three-component pharmaceutical model system ("PHARM-TM" blend). The widely used classical least squares regression (CLS) and partial least squares regression (PLS) quantification methods provided relatively poor root mean squared error of prediction (RMSEP) values: approximately 2-4% and 4-10% for CRYST-PM and PHARM-TM respectively. The residual plots of these models indicated the nonlinearity of the preprocessed data sets. More accurate quantitative results could be achieved with properly applied variable selection methods. It was observed that variable selection methods discarded the most intensive bands while less intensive ones were retained as the most informative spectral ranges. As a result not only the accuracy of concentration determination was enhanced, but the linearity of models was improved as well. This indicated that nonlinearity occurred especially at the intensive spectral bands. Other methods developed for handling nonlinearity were also capable of adapting to the spectral nature of both data sets. The RMSEP could be decreased this way to 1% in CRYST-PM and 3-6% in PHARM-TM. Raman maps with accurate real concentrations could be prepared this way. All quantitative models were compared by the non-parametric sum of ranking differences (SRD) method, which also proved that models based on variable selection or nonlinear methods provide better quantification.
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http://dx.doi.org/10.1016/j.jpba.2016.05.036DOI Listing
September 2016

Characterisation of the large-scale production process of oyster mushroom (Pleurotus ostreatus) with the analysis of succession and spatial heterogeneity of lignocellulolytic enzyme activities.

Fungal Biol 2015 Dec 22;119(12):1354-1363. Epub 2015 Oct 22.

Department of Microbiology, Eötvös Loránd University, Pázmány Péter sétány 1/C, 1117 Budapest, Hungary.

Oyster mushroom (Pleurotus ostreatus) lignocellulolytic enzyme activity pattern and variation was investigated in a large-scale facility from spawning until the end of the second flush. In the first cultivation cycle laccase production reached its peak during vegetative growth stage, while manganese-peroxidase showed the highest activity during fruiting body induction. Cellulose and hemicellulose degrading enzymes had maximal activity at the beginning of flush and harvest stage. The enzyme activities showed similar tendencies among five different mushroom substrate blocks representing a production house. The spatial variability analysis of enzyme activities pointed out the within substrate block heterogeneity as the main source if variation. This result was confirmed by Combined Cluster and Discriminant Analysis (CCDA) method showing minimal among block heterogeneity considering the whole investigation period; furthermore in the first cultivation cycle all blocks were grouped into one cluster.
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http://dx.doi.org/10.1016/j.funbio.2015.10.003DOI Listing
December 2015

Quantification of low drug concentration in model formulations with multivariate analysis using surface enhanced Raman chemical imaging.

J Pharm Biomed Anal 2015 Mar 30;107:318-24. Epub 2014 Dec 30.

Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary; MTA-BME Technical Analytical Chemistry Research Group, Szt. Gellért tér 4, H-1111 Budapest, Hungary.

This paper reports the application of surface enhanced Raman chemical imaging (SER-CI) as a potentially non-destructive quantitative analytical method for the investigation of model pharmaceutical formulations containing the active pharmaceutical ingredient (API) in low concentrations (0.5-2%). The application of chemometric techniques for processing the spectra enables the determination of API distribution in products of different concentrations. In addition, the applied multivariate curve resolution can be proper method to identify unexpected contaminants in illicit drugs. The drastic Raman signal enhancement in the presence of silver nanoparticles provides significantly improved calibration accuracy and, at the same time, radically decreased image acquisition time compared to conventional Raman chemical imaging.
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http://dx.doi.org/10.1016/j.jpba.2014.12.039DOI Listing
March 2015

Predicting final product properties of melt extruded solid dispersions from process parameters using Raman spectrometry.

J Pharm Biomed Anal 2014 Sep 27;98:166-77. Epub 2014 May 27.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary. Electronic address:

Raman spectrometry was utilized to estimate degraded drug percentage, residual drug crystallinity and glass-transition temperature in the case of melt-extruded pharmaceutical products. Tight correlation was shown between the results obtained by confocal Raman mapping and transmission Raman spectrometry, a PAT-compatible potential in-line analytical tool. Immediate-release spironolactone-Eudragit E solid dispersions were the model system, owing to the achievable amorphization and the heat-sensitivity of the drug compound. The deep investigation of the relationship between process parameters, residual drug crystallinity and degradation was performed using statistical tools and a factorial experimental design defining 54 different circumstances for the preparation of solid dispersions. From the examined factors, drug content (10, 20 and 30%), temperature (110, 130 and 150°C) and residence time (2.75, 11.00 and 24.75min) were found to have significant and considerable effect. By forming physically stable homogeneous dispersions, the originally very slow dissolution of the lipophilic and poorly water-soluble spironolactone was reasonably improved, making 3minute release possible in acidic medium.
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http://dx.doi.org/10.1016/j.jpba.2014.05.025DOI Listing
September 2014

One-year monitoring of meta-cleavage dioxygenase gene expression and microbial community dynamics reveals the relevance of subfamily I.2.C extradiol dioxygenases in hypoxic, BTEX-contaminated groundwater.

Syst Appl Microbiol 2013 Jul 23;36(5):339-50. Epub 2013 May 23.

Regional University Center of Excellence in Environmental Industry, Szent István University, Gödöllő, Hungary.

Aromatic hydrocarbons including benzene, toluene, ethyl-benzene, and xylene (BTEX) are frequent contaminants of groundwater, the major drinking water resource. Bioremediation is the only sustainable process to clean up these environments. Microbial degradation of BTEX compounds occurs rapidly under aerobic conditions but, in subsurface environments, the availability of oxygen is commonly restricted. Even so, the microaerobic degradation of aromatic compounds is still poorly understood. Hence, the dynamics of a bacterial community and the expression of meta-cleavage dioxygenase genes, with particular emphasis on subfamily I.2.C extradiol dioxygenase genes, were assessed over a 13-month period in a hypoxic, aromatic hydrocarbon-contaminated shallow groundwater by using sequence-aided terminal-restriction fragment length polymorphism (T-RFLP) and single-nucleotide primer extension (SNuPE), respectively. The bacterial 16S rRNA fingerprinting revealed the predominance of members of Rhodoferax, Azoarcus, Pseudomonas, and unknown bacteria related to Rhodocyclaceae. It was observed that mRNA transcripts of subfamily I.2.C extradiol dioxygenase genes were detected constantly over the monitoring period, and the detected sequences clustered into six distinct clusters. In order to reveal changes in the expression of these clusters over the monitoring period a SNuPE assay was developed. This quasi fingerprinting of functional gene expression provided the opportunity to link the investigated function to specific microbial populations. The results obtained can improve our understanding of aromatic hydrocarbon degradation under oxygen limitation and may benefit bioremediation research by demonstrating the usefulness of SNuPE for the monitoring of microbial populations involved in degradation process.
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http://dx.doi.org/10.1016/j.syapm.2013.03.008DOI Listing
July 2013

Remarkable impact of PAHs and TPHs on the richness and diversity of bacterial species in surface soils exposed to long-term hydrocarbon pollution.

World J Microbiol Biotechnol 2013 Nov 30;29(11):1989-2002. Epub 2013 Apr 30.

Department of Analytical Chemistry and Environmental Engineering, Polytehnical University of Bucharest, Splaiul Independenţei 313, 060042, Bucharest, Romania,

Nowadays, because of substantial use of petroleum-derived fuels the number and extension of hydrocarbon polluted terrestrial ecosystems is in growth worldwide. In remediation of aforementioned sites bioremediation still tends to be an innovative, environmentally attractive technology. Although huge amount of information is available concerning the hydrocarbon degradation potential of cultivable hydrocarbonoclastic bacteria little is known about the in situ long-term effects of petroleum derived compounds on the structure of soil microbiota. Therefore, in this study our aim was to determine the long-term impact of total petroleum hydrocarbons (TPHs), volatile petroleum hydrocarbons (VPHs), total alkyl benzenes (TABs) as well as of polycyclic aromatic hydrocarbons (PAHs) on the structure of bacterial communities of four different contaminated soil samples. Our results indicated that a very high amount of TPH affected positively the diversity of hydrocarbonoclastic bacteria. This finding was supported by the occurrence of representatives of the α-, β-, γ-Proteobacteria, Actinobacteria, Flavobacteriia and Bacilli classes. High concentration of VPHs and TABs contributed to the predominance of actinobacterial isolates. In PAH impacted samples the concentration of PAHs negatively correlated with the diversity of bacterial species. Heavily PAH polluted soil samples were mainly inhabited by the representatives of the β-, γ-Proteobacteria (overwhelming dominance of Pseudomonas sp.) and Actinobacteria.
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http://dx.doi.org/10.1007/s11274-013-1362-9DOI Listing
November 2013

Redox- and pH-responsive cysteamine-modified poly(aspartic acid) showing a reversible sol-gel transition.

Macromol Biosci 2013 May 19;13(5):633-40. Epub 2013 Mar 19.

Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest H-1111, Hungary.

Synthesis and characterization of a pH- and redox-sensitive hydrogel of poly(aspartic acid) are reported. Reversible gelation and dissolution are achieved both in dimethylformamide and in aqueous medium via a thiol-disulphide interconversion in the side chain of the polymers. Structural changes are confirmed by Raman microscopy and rheological measurements. Injectable aqueous solutions of thiolated poly(aspartic acid) can be converted into mechanically stable gels by oxidation, which can be useful for drug encapsulation and targeted delivery. Reduction-facilitated release of an entrapped drug from disulphide cross-linked hydrogels is studied.
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http://dx.doi.org/10.1002/mabi.201200420DOI Listing
May 2013

Challenges in detecting magnesium stearate distribution in tablets.

AAPS PharmSciTech 2013 Mar 2;14(1):435-44. Epub 2013 Feb 2.

Division of Pharmaceutical Technology, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5E, P.O. Box 56, 00014, Helsinki, Finland.

Magnesium stearate (MS) is the most commonly used lubricant in pharmaceutical industry. During blending, MS particles form a thin layer on the surfaces of the excipient and drug particles prohibiting the bonding from forming between the particles. This hydrophobic layer decreases the tensile strength of tablets and prevents water from penetrating into the tablet restraining the disintegration and dissolution of the tablets. Although overlubrication of the powder mass during MS blending is a well-known problem, the lubricant distribution in tablets has traditionally been challenging to measure. There is currently no adequate analytical method to investigate this phenomenon. In this study, the distribution of MS in microcrystalline cellulose (MCC) tablets was investigated using three different blending scales. The crushing strength of the tablets was used as a secondary response, as its decrease is known to result from the overlubrication. In addition, coating of the MCC particles by MS in intact tablets was detected using Raman microscopic mapping. MS blending was more efficient in larger scales. Raman imaging was successfully applied to characterize MS distribution in MCC tablets despite low concentration of MS. The Raman method can provide highly valuable visual information about the proceeding of the MS blending process. However, the measuring set-up has to be carefully planned to establish reliable and reproducible results.
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http://dx.doi.org/10.1208/s12249-013-9927-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3581680PMC
March 2013

Investigation of drug distribution in tablets using surface enhanced Raman chemical imaging.

J Pharm Biomed Anal 2013 Mar 22;76:145-51. Epub 2012 Dec 22.

Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri út 59-67, Hungary.

This paper reports the first application of surface enhanced Raman chemical imaging on pharmaceutical tablets containing the active ingredient (API) in very low concentrations. Taking advantage of the extremely intensive Raman signals in the presence of silver colloids, image aquisition time was radically decreased. Moreover, the investigation of drug distribution below the detection limit of regular micro-Raman spectrometry was made feasible. The characteristics of different manufacturing technologies could be revealed at very low API concentrations by using chemometric methods for processing and evaluating the large number of varying spectra provided with this imaging method.
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http://dx.doi.org/10.1016/j.jpba.2012.12.017DOI Listing
March 2013

Solvent-free melt electrospinning for preparation of fast dissolving drug delivery system and comparison with solvent-based electrospun and melt extruded systems.

J Pharm Sci 2013 Feb 18;102(2):508-17. Epub 2012 Nov 18.

Organic Chemistry and Technology Department, Budapest University of Technology and Economics, Budapest H-1111, Hungary.

The solvent-free melt electrospinning (MES) method was developed to prepare a drug delivery system with fast release of carvedilol (CAR), a drug with poor water solubility. To the authors knowledge, this is the first report for preparing drug-loaded melt electrospun fibers. Cationic methacrylate copolymer of Eudragit® E type was used as a fiber forming polymer matrix. For comparison, ethanol-based electrospinning and melt extrusion (EX) methods were used to produce samples that had the same composition as the melt electrospun system. According to the results of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and Fourier transformed infrared spectrometry investigations, amorphous solid nanodispersions/solutions of CAR in Eudragit® E matrix were obtained in all cases with 20 m/m % drug content. In vitro drug release in acidic media from the extrudates was significantly faster (5 min) than that from crystalline CAR. Moreover, ultrafast drug release was achieved from the solvent-free melt and ethanol-based electrospun samples because of their huge surface area and the soluble polymer matrix in the acidic media. These results demonstrate that solvent-free MES is a promising, novel technique for the production of drug delivery systems with enhanced dissolution because it can combine the advantages of EX (e.g., solvent-free, continuous process, and effective amorphization) and solvent-based electrospinning (huge product surface area).
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http://dx.doi.org/10.1002/jps.23374DOI Listing
February 2013

Solvent effect on the vibrational spectra of Carvedilol.

Spectrochim Acta A Mol Biomol Spectrosc 2012 Sep 23;95:148-64. Epub 2012 Apr 23.

Department of Physical Chemistry and Material Science, Budapest University of Technology and Economics, H-1521 Budapest, Budafokiút 8, Hungary.

Carvedilol (CRV) is an important medicament for heart arrhythmia. The aim of this work was the interpretation of its vibrational spectra with consideration on the solvent effect. Infrared and Raman spectra were recorded in solid state as well in solution. The experimental spectra were evaluated using DFT quantum chemical calculations computing the optimized structure, atomic net charges, vibrational frequencies and force constants. The same calculations were done for the molecule in DMSO and aqueous solutions applying the PCM method. The calculated force constants were scaled to the experimentally observed solid state frequencies. The characters of the vibrational modes were determined by their potential energy distributions. Solvent effects on the molecular properties were interpreted. Based on these results vibrational spectra were simulated.
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http://dx.doi.org/10.1016/j.saa.2012.04.029DOI Listing
September 2012

An improved sequence-aided T-RFLP analysis of bacterial succession during oyster mushroom substrate preparation.

Microb Ecol 2012 Oct 22;64(3):702-13. Epub 2012 May 22.

Department of Microbiology, Eötvös Loránd University, Pázmány Péter sétány 1/C, 1117, Budapest, Hungary.

While oyster mushroom (Pleurotus spp.) is one of the most popular cultivated edible mushrooms, there is scanty information about the microbial community taking part in mushroom substrate production. In this study, an improved sequence-aided terminal restriction fragment length polymorphism (T-RFLP) was used to identify and (semi-)quantify the dominant bacteria of oyster mushroom substrate preparation. The main features of the improved T-RFLP data analysis were the alignment of chromatograms with variable clustering thresholds, the visualization of data matrix with principal component analysis ordination superimposed with cluster analysis, and the search for stage-specific peaks (bacterial taxa) with similarity percentage (analysis of similarity) analysis, followed by identification with clone libraries. By applying this method, the dominance of the following bacterial genera was revealed during oyster mushroom substrate preparation: Pseudomonas and Sphingomonas at startup, Bacillus, Geobacillus, Ureibacillus, Pseudoxanthomonas, and Thermobispora at the end of partial composting, and finally several genera of Actinobacteria, Thermus, Bacillus, Geobacillus, Thermobacillus, and Ureibacillus in the mature substrate. As the proportion of uncultured bacteria increased during the process, it is worth establishing strain collections from partial composting and from mature substrate for searching new species.
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http://dx.doi.org/10.1007/s00248-012-0063-5DOI Listing
October 2012

Ferrate treatment for inactivation of bacterial community in municipal secondary effluent.

Bioresour Technol 2012 Mar 17;107:116-21. Epub 2011 Dec 17.

Cooperative Research Center for Environmental Sciences, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary.

This paper demonstrates the effect of ferrate [Fe(VI)-compound], an environmental friendly multi-purpose reagent, in municipal secondary effluent treatment. The purpose was to study the inactivation capability of ferrate and for the first time to compare the effect and efficiency of Fe(VI) with the widely used disinfectant, chlorine gas on the indigenous bacterial community in the case of secondary effluents. The most probable number technique (MPN) was applied for the determination of cultivable heterotrophic bacterial abundance and terminal restriction fragment length polymorphism (T-RFLP) analysis for comparing bacterial communities. The study demonstrated that (i) ferrate and chlorine had different effect on the total bacterial community of secondary effluents, (ii) low ferrate dose [5 mg L(-1) Fe(VI)] was sufficient for >99.9% reduction of indigenous bacteria, and (iii) a similar dosage was also effective in the inactivation of chlorine-resistant bacteria.
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http://dx.doi.org/10.1016/j.biortech.2011.12.053DOI Listing
March 2012

Testing the performance of pure spectrum resolution from Raman hyperspectral images of differently manufactured pharmaceutical tablets.

Anal Chim Acta 2012 Jan 15;712:45-55. Epub 2011 Nov 15.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budapest, Hungary.

Chemical imaging is a rapidly emerging analytical method in pharmaceutical technology. Due to the numerous chemometric solutions available, characterization of pharmaceutical samples with unknown components present has also become possible. This study compares the performance of current state-of-the-art curve resolution methods (multivariate curve resolution-alternating least squares, positive matrix factorization, simplex identification via split augmented Lagrangian and self-modelling mixture analysis) in the estimation of pure component spectra from Raman maps of differently manufactured pharmaceutical tablets. The batches of different technologies differ in the homogeneity level of the active ingredient, thus, the curve resolution methods are tested under different conditions. An empirical approach is shown to determine the number of components present in a sample. The chemometric algorithms are compared regarding the number of detected components, the quality of the resolved spectra and the accuracy of scores (spectral concentrations) compared to those calculated with classical least squares, using the true pure component (reference) spectra. It is demonstrated that using appropriate multivariate methods, Raman chemical imaging can be a useful tool in the non-invasive characterization of unknown (e.g. illegal or counterfeit) pharmaceutical products.
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http://dx.doi.org/10.1016/j.aca.2011.10.065DOI Listing
January 2012

[Real-time monitoring of drug crystallization with and without additives].

Acta Pharm Hung 2011 ;81(3):109-24

Budapesti Muszaki és Gazdaságtudományi Egyetem, Szerves Kémia és Technológia Tanszék, 1111 Budapest, Budafoki út 8.

Crystallization processes can be evaluated from both kinetic and thermodinamic point of view with real-time analitical methods, effects of production parameters on the final quality can be estimated as well. Consequently there is an increasing emphasis on analytical devices being applicable for real-time detection. Among these techniques Raman spectrometry is advantageously utilizable for real-time monitoring of crystallizations. Impurities can dramatically change the nucleation and crystal growth, thus they can alter the physical and chemical properties of the final product. The use of different additives (polymers;surface active ingredients) in the crystallization step in order to modify the product morphology methodically is a new direction in the scientific literature. This study provides an overview of crystallization processes in the presence of additives as well as a summary concerning the monitoring of the drug crystallizations by real-time Raman spectrometry. Furthermore the effect of polyvinyl-pyrrolidone was examined in the course of cooling crystallization of Donepezil HCl, while the process was monitored by in-line Raman spectrometry.
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January 2012

Comparison of electrospun and extruded Soluplus®-based solid dosage forms of improved dissolution.

J Pharm Sci 2012 Jan 23;101(1):322-32. Epub 2011 Aug 23.

Organic Chemistry and Technology Department, Budapest University of Technology and Economics, H-1111 Budapest, Hungary.

Electrospinning (ES) and extrusion of a poorly water-soluble active pharmaceutical ingredient were used to improve its dissolution, which is a major challenge in the field of pharmaceutical technology. Spironolactone was applied as model drug and recently developed polyvinyl caprolactame-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) was used as carrier matrix and solubilizer. ES of the polymer matrix from ethanol solution was optimized at first without spironolactone and then the cosolution of the drug and the carrier was used for forming electrospun fibers. It resulted in real solid solution due to its very efficient amorphization effect. On the contrary, a low amount of crystalline spironolactone appeared in the extrudates according to Raman microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). Raman microspectrometry had the lowest detection limit of spironolactone crystals compared with XRD and differential scanning calorimetry. Both ES and extrusion techniques resulted in significantly improved dissolution. Electrospun ultrafine fibers increased the dissolution more effectively, owing to the formed solid solution and huge surface. The developed continuous technologies demonstrate great potential to tackle the challenge of inadequate dissolution of poorly water-soluble drugs in several cases.
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http://dx.doi.org/10.1002/jps.22731DOI Listing
January 2012

Thermus composti sp. nov., isolated from oyster mushroom compost.

Int J Syst Evol Microbiol 2012 Jul 19;62(Pt 7):1486-1490. Epub 2011 Aug 19.

Department of Microbiology, Eötvös Loránd University, Pázmány Péter Sétány 1/c, H-1117 Budapest, Hungary.

A Gram-stain-negative, rod-shaped bacterium (strain K-39(T)) was isolated from the thermophilic phase of the composting process for oyster mushroom substrate preparation. The strain grew at 40-80 °C (optimum, 65-75 °C), at pH 5-9 (optimum, pH 7), in media containing up to 1.5% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain K-39(T) formed a distinct lineage within the genus Thermus. Its closest cultivated relative was Thermus islandicus PRI 3838(T) (96.8% similarity). The DNA G+C content of strain K-39(T) was 71.3 mol%. The new strain could be differentiated from the related taxa by not being able to hydrolyse starch. The predominant fatty acids of strain K-39(T) were iso-C(17:0) and anteiso-C(17:0). Strain K-39(T) contained a lower amount of the fatty acid iso-C(15:0) as compared to related species of the genus Thermus. The predominant respiratory quinone of the new isolate was menaquinone MK-8. On the basis of a taxonomic study using a polyphasic approach, strain K-39(T) is considered to represent a novel species of the genus Thermus, for which the name Thermus composti sp. nov. is proposed. The type strain is K-39(T) (=DSM 21686(T)=NCAIM B 02340(T)).
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http://dx.doi.org/10.1099/ijs.0.030866-0DOI Listing
July 2012

Characterization of melt extruded and conventional Isoptin formulations using Raman chemical imaging and chemometrics.

Int J Pharm 2011 Oct 23;419(1-2):107-13. Epub 2011 Jul 23.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budafoki út 8., H-1111 Budapest, Hungary.

Isoptin SR-E (Meltrex(®)) extruded tablets were assumed in a recent paper to be prepared with a composition different from a conventional (Isoptin SR) formulation. This study reveals, however, using Raman mapping and chemometric evaluation, that in fact the same composition, comprising Na alginate as polymer matrix, is used in both products. It means that only the difference in the manufacturing technology causes the reported sustained release of verapamil hydrochloride even in ethanol containing dissolution media. The products are compared based on the obtained Raman chemical images, which allowed concluding in a new structure-based explanation for the differences in the dissolution profiles in the presence of ethanol. It is also shown that extrusion technology influences the dissolution profile effectively, even in the cases when solid solution is formed only partially.
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http://dx.doi.org/10.1016/j.ijpharm.2011.07.023DOI Listing
October 2011

Characterization of drug-cyclodextrin formulations using Raman mapping and multivariate curve resolution.

J Pharm Biomed Anal 2011 Aug 12;56(1):38-44. Epub 2011 May 12.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budafoki Ut 8, H-1111 Budapest, Hungary.

Raman chemical imaging was used in the characterization of drug-excipient interactions between a drug and different types of cyclodextrins. Detailed analysis was carried out regarding the interactions between the active ingredient (API) and the cyclodextrins and the heterogeneity of the samples was studied using multivariate curve resolution-alternating least squares algorithm. The amount of recrystallized pure API was also estimated using the same curve resolution method. The Raman mapping results were validated via scanning electron microscopy-energy dispersive X-ray spectroscopy and X-ray powder diffraction. Raman mapping was found to be suitable to detect traces of pure crystalline API below the detection limit of X-ray powder diffraction.
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http://dx.doi.org/10.1016/j.jpba.2011.05.005DOI Listing
August 2011

[Application possibilities of chemical imaging in pharmaceutical technology].

Acta Pharm Hung 2009 ;79(3):104-16

Budapesti Muszaki es Gazdaságtudományi Egyetem, Szerves Kémia es Technológia Tanszék, Budapest, Budafoki u. 8. - 1111.

Chemical imaging is a novel analytical method that simultaneously delivers spatial, chemical, structural, and functional information on the dosage forms. Both infrared and Raman spectroscopic imaging may serve as useful nondestructive analytical techniques in the pharmaceutical product development and quality control. Most important application possibilities are reviewed and some studies demonstrate the advantages of the structure exploration. Raman imaging is suitable to understand and control the quality attributes of different dosage forms.
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April 2010

Microbial community structure changes during oyster mushroom substrate preparation.

Appl Microbiol Biotechnol 2010 Mar 5;86(1):367-75. Epub 2009 Dec 5.

Department of Microbiology, Eötvös Loránd University, Pázmány Péter sétány 1/C, 1117 Budapest, Hungary.

Although oyster mushroom (Pleurotus spp.) is a valuable food, cultivated worldwide on an industrial scale, still very little is known about the microbial dynamics during oyster mushroom substrate preparation. Therefore, the characterization of the microbial dynamics by chemical and biological tools was the objective of this study. During substrate preparation, enzymatic digestibility of the substrate improved by 77%, whereas the cellulose and hemicellulose to lignin ratios decreased by 9% and 19%, respectively. Fluorescein diacetate hydrolysis reached its minimum value at the temperature maximum of the process during the composting phase and exceeded the initial level at the end of the process. Fungal species played part in the initial mesophilic phase of the substrate preparation process, but they disappeared after pasteurization in tunnels at constant elevated temperatures. Changes in the microbiota showed a marked bacterial community succession during substrate preparation investigated by 16S ribosomal deoxyribonucleic acid-based terminal restriction fragment length polymorphism (T-RFLP). Mature samples represented the least variance, which indicated the effect of the standardized preparation protocol. The relation between mushroom yield and the bacterial community T-RFLP fingerprints was investigated, but the uniformity of mushroom yields did not support any significant correlation.
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http://dx.doi.org/10.1007/s00253-009-2371-3DOI Listing
March 2010

Raman microscopic evaluation of technology dependent structural differences in tablets containing imipramine model drug.

J Pharm Biomed Anal 2010 Jan 4;51(1):30-8. Epub 2009 Aug 4.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budapest, Hungary.

Raman imaging method was used to characterize the effect of different manufacturing technologies on properties of the produced tablets, such as compound distribution, polymorphism, strength, and estimated active pharmaceutical ingredient (API) content. The obtained chemical maps were evaluated based on their visual appearance and on the statistical properties of the component scores obtained by direct classical least squares (DCLS) modelling. It is demonstrated that changes in the distribution of the API and excipients can be detected with chemical imaging and these differences are in close relationship with the applied granulation method and with the mechanical properties of the analyzed tablet. It is also shown that the chemical images used for characterizing the component distribution can also be processed for obtaining a cautious estimation to the mass fractions of the components.
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http://dx.doi.org/10.1016/j.jpba.2009.07.030DOI Listing
January 2010

DGGE and T-RFLP analysis of bacterial succession during mushroom compost production and sequence-aided T-RFLP profile of mature compost.

Microb Ecol 2009 Apr 25;57(3):522-33. Epub 2008 Jul 25.

Department of Microbiology, Eötvös Loránd University, Budapest, Hungary.

The amount of button mushroom (Agaricus bisporus) harvested from compost is largely affected by the microbial processes taking place during composting and the microbes inhabiting the mature compost. In this study, the microbial changes during the stages of this specific composting process were monitored, and the dominant bacteria of the mature compost were identified to reveal the microbiological background of the favorable properties of the heat-treated phase II mushroom compost. 16S ribosomal deoxyribonucleic acid (rDNA)-based denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) molecular fingerprinting methods were used to track the succession of microbial communities in summer and winter composting cycles. DNA from individual DGGE bands were reamplified and subjected to sequence analysis. Principal component analysis of fingerprints of the composting processes showed intensive changes in bacterial community during the 22-day procedure. Peak temperature samples grouped together and were dominated by Thermus thermophilus. Mature compost patterns were almost identical by both methods (DGGE, T-RFLP). To get an in-depth analysis of the mature compost bacterial community, the sequence data from cultivation of the bacteria and cloning of environmental 16S rDNA were uniquely coupled with the output of the environmental T-RFLP fingerprints (sequence-aided T-RFLP). This method revealed the dominance of a supposedly cellulose-degrading consortium composed of phylotypes related to Pseudoxanthomonas, Thermobifida, and Thermomonospora.
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http://dx.doi.org/10.1007/s00248-008-9424-5DOI Listing
April 2009