Publications by authors named "Jana Voříšková"

17 Publications

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Symbiosis of isoetid plant species with arbuscular mycorrhizal fungi under aquatic versus terrestrial conditions.

Mycorrhiza 2021 May 24;31(3):273-288. Epub 2021 Jan 24.

Institute of Botany, The Czech Academy of Sciences, 242 43, Průhonice, Czech Republic.

Arbuscular mycorrhizal fungi (AMF) colonize the roots of numerous aquatic and wetland plants, but the establishment and functioning of mycorrhizal symbiosis in submerged habitats have received only little attention. Three pot experiments were conducted to study the interaction of isoetid plants with native AMF. In the first experiment, arbuscular mycorrhizal (AM) symbiosis did not establish in roots of Isoëtes echinospora and I. lacustris, while Littorella uniflora roots were highly colonized. Shoot and root biomass of L. uniflora were, however, not affected by AMF inoculation, and only one of nine AMF isolates significantly increased shoot P concentration. In the second experiment, we compared colonization by three Glomus tetrastratosum isolates of different cultivation history and origin (aquatic versus terrestrial) and their effects on L. uniflora growth and phosphorus nutrition under submerged versus terrestrial conditions. The submerged cultivation considerably slowed, but did not inhibit mycorrhizal root colonization, regardless of isolate identity. Inoculation with any AMF isolate improved plant growth and P uptake under terrestrial, but not submerged conditions. In the final experiment, we compared the communities of AMF established in two cultivation regimes of trap cultures with lake sediments, either submerged on L. uniflora or terrestrial on Zea mays. After 2-year cultivation, we did not detect a significant effect of cultivation regime on AMF community composition. In summary, although submerged conditions do not preclude the development of functional AM symbiosis, the contribution of these symbiotic fungi to the fitness of their hosts seems to be considerably less than under terrestrial conditions.
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http://dx.doi.org/10.1007/s00572-020-01017-yDOI Listing
May 2021

Culturing of "Unculturable" Subsurface Microbes: Natural Organic Carbon Source Fuels the Growth of Diverse and Distinct Bacteria From Groundwater.

Front Microbiol 2020 17;11:610001. Epub 2020 Dec 17.

Department of Ecology, Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.

Recovery and cultivation of diverse environmentally-relevant microorganisms from the terrestrial subsurface remain a challenge despite recent advances in modern molecular technology. Here, we applied complex carbon (C) sources, i.e., sediment dissolved organic matter (DOM) and bacterial cell lysate, to enrich groundwater microbial communities for 30 days. As comparisons, we also included enrichments amended with simple C sources including glucose, acetate, benzoate, oleic acid, cellulose, and mixed vitamins. Our results demonstrate that complex C is far more effective in enriching diverse and distinct microorganisms from groundwater than simple C. Simple C enrichments yield significantly lower biodiversity, and are dominated by few phyla (e.g., and ), while microcosms enriched with complex C demonstrate significantly higher biodiversity including phyla that are poorly represented in published culture collections (e.g., , , and ). Subsequent isolation from complex C enrichments yielded 228 bacterial isolates representing five phyla, 17 orders, and 56 distinct species, including candidate novel, rarely cultivated, and undescribed organisms. Results from this study will substantially advance cultivation and isolation strategies for recovering diverse and novel subsurface microorganisms. Obtaining axenic representatives of "once-unculturable" microorganisms will enhance our understanding of microbial physiology and function in different biogeochemical niches of terrestrial subsurface ecosystems.
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http://dx.doi.org/10.3389/fmicb.2020.610001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7773641PMC
December 2020

GlobalFungi, a global database of fungal occurrences from high-throughput-sequencing metabarcoding studies.

Sci Data 2020 07 13;7(1):228. Epub 2020 Jul 13.

Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, 14220, Praha 4, Czech Republic.

Fungi are key players in vital ecosystem services, spanning carbon cycling, decomposition, symbiotic associations with cultivated and wild plants and pathogenicity. The high importance of fungi in ecosystem processes contrasts with the incompleteness of our understanding of the patterns of fungal biogeography and the environmental factors that drive those patterns. To reduce this gap of knowledge, we collected and validated data published on the composition of soil fungal communities in terrestrial environments including soil and plant-associated habitats and made them publicly accessible through a user interface at https://globalfungi.com . The GlobalFungi database contains over 600 million observations of fungal sequences across > 17 000 samples with geographical locations and additional metadata contained in 178 original studies with millions of unique nucleotide sequences (sequence variants) of the fungal internal transcribed spacers (ITS) 1 and 2 representing fungal species and genera. The study represents the most comprehensive atlas of global fungal distribution, and it is framed in such a way that third-party data addition is possible.
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http://dx.doi.org/10.1038/s41597-020-0567-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7359306PMC
July 2020

Fast response of fungal and prokaryotic communities to climate change manipulation in two contrasting tundra soils.

Environ Microbiome 2019 Sep 18;14(1). Epub 2019 Sep 18.

Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.

Background: Climate models predict substantial changes in temperature and precipitation patterns across Arctic regions, including increased winter precipitation as snow in the near future. Soil microorganisms are considered key players in organic matter decomposition and regulation of biogeochemical cycles. However, current knowledge regarding their response to future climate changes is limited. Here, we explore the short-term effect of increased snow cover on soil fungal, bacterial and archaeal communities in two tundra sites with contrasting water regimes in Greenland. In order to assess seasonal variation of microbial communities, we collected soil samples four times during the plant-growing season.

Results: The analysis revealed that soil microbial communities from two tundra sites differed from each other due to contrasting soil chemical properties. Fungal communities showed higher richness at the dry site whereas richness of prokaryotes was higher at the wet tundra site. We demonstrated that fungal and bacterial communities at both sites were significantly affected by short-term increased snow cover manipulation. Our results showed that fungal community composition was more affected by deeper snow cover compared to prokaryotes. The fungal communities showed changes in both taxonomic and ecological groups in response to climate manipulation. However, the changes were not pronounced at all sampling times which points to the need of multiple sampling in ecosystems where environmental factors show seasonal variation. Further, we showed that effects of increased snow cover were manifested after snow had melted.

Conclusions: We demonstrated rapid response of soil fungal and bacterial communities to short-term climate manipulation simulating increased winter precipitation at two tundra sites. In particular, we provide evidence that fungal community composition was more affected by increased snow cover compared to prokaryotes indicating fast adaptability to changing environmental conditions. Since fungi are considered the main decomposers of complex organic matter in terrestrial ecosystems, the stronger response of fungal communities may have implications for organic matter turnover in tundra soils under future climate.
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http://dx.doi.org/10.1186/s40793-019-0344-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7989089PMC
September 2019

Sympatric diploid and tetraploid cytotypes of Centaurea stoebe s.l. do not differ in arbuscular mycorrhizal communities and mycorrhizal growth response.

Am J Bot 2018 12 14;105(12):1995-2007. Epub 2018 Dec 14.

Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic.

Premise Of The Study: Genome duplication is associated with multiple changes at different levels, including interactions with pollinators and herbivores. Yet little is known whether polyploidy may also shape belowground interactions.

Methods: To elucidate potential ploidy-specific interactions with arbuscular mycorrhizal fungi (AMF), we compared mycorrhizal colonization and assembly of AMF communities in roots of diploid and tetraploid Centaurea stoebe s.l. (Asteraceae) co-occurring in a Central European population. In a follow-up greenhouse experiment, we tested inter-cytotype differences in mycorrhizal growth response by combining ploidy, substrate, and inoculation with native AMF in a full-factorial design.

Key Results: All sampled plants were highly colonized by AMF, with the Glomeraceae predominating. AMF-community composition revealed by 454-pyrosequencing reflected the spatial distribution of the hosts, but not their ploidy level or soil characteristics. In the greenhouse experiment, the tetraploids produced more shoot biomass than the diploids did when grown in a more fertile substrate, while no inter-cytotype differences were found in a less fertile substrate. AMF inoculation significantly reduced plant growth and improved P uptake, but its effects did not differ between the cytotypes.

Conclusions: The results do not support our hypotheses that the cytotype structure in a mixed-ploidy population of C. stoebe is mirrored in AMF-community composition and that ploidy-specific fungal communities contribute to cytotype co-existence. Causes and implications of the observed negative growth response to AMF are discussed.
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http://dx.doi.org/10.1002/ajb2.1206DOI Listing
December 2018

Inter-laboratory testing of the effect of DNA blocking reagent G2 on DNA extraction from low-biomass clay samples.

Sci Rep 2018 04 9;8(1):5711. Epub 2018 Apr 9.

Center for Permafrost (CENPERM) and Department of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.

Here we show that a commercial blocking reagent (G2) based on modified eukaryotic DNA significantly improved DNA extraction efficiency. We subjected G2 to an inter-laboratory testing, where DNA was extracted from the same clay subsoil using the same batch of kits. The inter-laboratory extraction campaign revealed large variation among the participating laboratories, but the reagent increased the number of PCR-amplified16S rRNA genes recovered from biomass naturally present in the soils by one log unit. An extensive sequencing approach demonstrated that the blocking reagent was free of contaminating DNA, and may therefore also be used in metagenomics studies that require direct sequencing.
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http://dx.doi.org/10.1038/s41598-018-24082-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5890260PMC
April 2018

Wood Ash Induced pH Changes Strongly Affect Soil Bacterial Numbers and Community Composition.

Front Microbiol 2017 28;8:1400. Epub 2017 Jul 28.

Department of Environmental Science, Aarhus UniversityRoskilde, Denmark.

Recirculation of wood ash from energy production to forest soil improves the sustainability of this energy production form as recycled wood ash contains nutrients that otherwise would be lost at harvest. In addition, wood-ash is beneficial to many soils due to its inherent acid-neutralizing capabilities. However, wood ash has several ecosystem-perturbing effects like increased soil pH and pore water electrical conductivity both known to strongly impact soil bacterial numbers and community composition. Studies investigating soil bacterial community responses to wood ash application remain sparse and the available results are ambiguous and remain at a general taxonomic level. Here we investigate the response of bacterial communities in a spruce forest soil to wood ash addition corresponding to 0, 5, 22, and 167 t wood ash ha. We used culture-based enumerations of general bacteria, and sporeforming bacteria combined with 16S rRNA gene amplicon sequencing to valuate soil bacterial responses to wood ash application. Results showed that wood ash addition strongly increased soil pH and electrical conductivity. Soil pH increased from acidic through neutral at 22 t ha to alkaline at 167 t ha. Bacterial numbers significantly increased up to a wood ash dose of 22 t ha followed by significant decrease at 167 t ha wood ash. The soil bacterial community composition changed after wood ash application with copiotrophic bacteria responding positively up to a wood ash dose of 22 t ha while the adverse effect was seen for oligotrophic bacteria. Marked changes in bacterial community composition occurred at a wood ash dose of 167 t ha with a single alkaliphilic genus dominating. Additionally, spore-formers became abundant at an ash dose of 167 t ha whereas this was not the case at lower ash doses. Lastly, bacterial richness and diversity strongly decreased with increasing amount of wood ash applied. All of the observed bacterial responses can be directly explained by the wood ash induced changes in pH, electrical conductivity and the addition of wood ash inherent nutrients.
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http://dx.doi.org/10.3389/fmicb.2017.01400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532396PMC
July 2017

Bacterial succession on decomposing leaf litter exhibits a specific occurrence pattern of cellulolytic taxa and potential decomposers of fungal mycelia.

FEMS Microbiol Ecol 2016 11 18;92(11). Epub 2016 Aug 18.

Laboratory of Environmental Microbiology, Institute of Microbiology of the CAS, Vídeňská 1083, 14220 Praha 4, Czech Republic.

The decomposition of dead plant biomass contributes to the carbon cycle and is one of the key processes in temperate forests. While fungi in litter decomposition drive the chemical changes occurring in litter, the bacterial community appears to be important as well, especially later in the decomposition process when its abundance increases. In this paper, we describe the bacterial community composition in live Quercus petraea leaves and during the subsequent two years of litter decomposition. Members of the classes Alpha-, Beta- and Gammaproteobacteria and the phyla Actinobacteria, Bacteroidetes and Acidobacteria were dominant throughout the experiment. Bacteria present in the oak phyllosphere were rapidly replaced by other taxa after leaf senescence. There were dynamic successive changes in community composition, in which the early-stage (months 2-4), mid-stage (months 6-8) and late-stage (months 10-24) decomposer communities could be distinguished, and the diversity increased with time. Bacteria associated with dead fungal mycelium were important during initial decomposition, with sequence relative abundances of up to 40% of the total bacterial community in months 2 and 4 when the highest fungal biomass was observed. Cellulose-decomposing bacteria were less frequent, with abundance ranging from 4% to 15%. The bacterial community dynamics reflects changes in the availability of possible resources either of the plant or microbial origin.
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http://dx.doi.org/10.1093/femsec/fiw177DOI Listing
November 2016

Polycyclic aromatic hydrocarbons degradation and microbial community shifts during co-composting of creosote-treated wood.

J Hazard Mater 2016 Jan 18;301:17-26. Epub 2015 Aug 18.

Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, CZ-142 20 Prague 4, Czech Republic; Institute of Environmental Studies, Faculty of Science, Charles University, Benátská 2, CZ-128 01 Prague 2, Czech Republic. Electronic address:

The feasibility of decontaminating creosote-treated wood (CTW) by co-composting with agricultural wastes was investigated using two bulking agents, grass cuttings (GC) and broiler litter (BL), each employed at a 1:1 ratio with the matrix. The initial concentration of total polycyclic aromatic hydrocarbons (PAHs) in CTW (26,500 mg kg(-1)) was reduced to 3 and 19% after 240 d in GC and BL compost, respectively. PAH degradation exceeded the predicted bioaccesible threshold, estimated through sequential supercritical CO2 extraction, together with significant detoxification, assessed by contact tests using Vibrio fisheri and Hordeum vulgare. GC composting was characterized by high microbial biomass growth in the early phases, as suggested by phospholipid fatty acid analyses. Based on the 454-pyrosequencing results, fungi (mostly Saccharomycetales) constituted an important portion of the microbial community, and bacteria were characterized by rapid shifts (from Firmicutes (Bacilli) and Actinobacteria to Proteobacteria). However, during BL composting, larger amounts of prokaryotic and eukaryotic PLFA markers were observed during the cooling and maturation phases, which were dominated by Proteobacteria and fungi belonging to the Ascomycota and those putatively related to the Glomeromycota. This work reports the first in-depth analysis of the chemical and microbiological processes that occur during the co-composting of a PAH-contaminated matrix.
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http://dx.doi.org/10.1016/j.jhazmat.2015.08.023DOI Listing
January 2016

Niche partitioning in arbuscular mycorrhizal communities in temperate grasslands: a lesson from adjacent serpentine and nonserpentine habitats.

Mol Ecol 2015 Apr;24(8):1831-43

Institute of Botany, The Czech Academy of Science, CZ-252 43, Průhonice, Czech Republic; Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, EE-510 05, Tartu, Estonia; Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, CZ-128 44, Prague 2, Czech Republic.

Arbuscular mycorrhizal fungi (AMF) represent an important soil microbial group playing a fundamental role in many terrestrial ecosystems. We explored the effects of deterministic (soil characteristics, host plant life stage, neighbouring plant communities) and stochastic processes on AMF colonization, richness and community composition in roots of Knautia arvensis (Dipsacaceae) plants from three serpentine grasslands and adjacent nonserpentine sites. Methodically, the study was based on 454-sequencing of the ITS region of rDNA. In total, we detected 81 molecular taxonomical operational units (MOTUs) belonging to the Glomeromycota. Serpentine character of the site negatively influenced AMF root colonization, similarly as higher Fe concentration. AMF MOTUs richness linearly increased along a pH gradient from 3.5 to 5.8. Contrary, K and Cr soil concentration had a negative influence on AMF MOTUs richness. We also detected a strong relation between neighbouring plant community composition and AMF MOTUs richness. Although spatial distance between the sampled sites (c. 0.3-3 km) contributed to structuring AMF communities in K. arvensis roots, environmental parameters were key factors in this respect. In particular, the composition of AMF communities was shaped by the complex of serpentine conditions, pH and available soil Ni concentration. The composition of AMF communities was also dependent on host plant life stage (vegetative vs. generative). Our study supports the dominance of deterministic factors in structuring AMF communities in heterogeneous environment composed of an edaphic mosaic of serpentine and nonserpentine soils.
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http://dx.doi.org/10.1111/mec.13147DOI Listing
April 2015

Top-down control of soil fungal community composition by a globally distributed keystone consumer.

Ecology 2013 Nov;94(11):2518-28

Cardiff School of Biosciences, Cardiff University, Cardiff CF10 AX, United Kingdom.

The relative contribution of top-down and bottom-up processes regulating primary decomposers can influence the strength of the link between the soil animal community and ecosystem functioning. Although soil bacterial communities are regulated by bottom-up and top-down processes, the latter are considered to be less important in structuring the diversity and functioning of fungal-dominated ecosystems. Despite the huge diversity of mycophagous (fungal-feeding) soil fauna, and their potential to reverse the outcomes of competitive fungal interactions, top-down grazing effects have never been found to translate to community-level changes. We constructed soil mesocosms to investigate the potential of isopods grazing on cord-forming basidiomycete fungi to influence the community composition and functioning of a complex woodland soil microbial community. Using metagenomic sequencing we provide conclusive evidence of direct top-down control at the community scale in fungal-dominated woodland soil. By suppressing the dominant cord-forming basidiomycete fungi, isopods prevented the competitive exclusion of surrounding litter fungi, increasing diversity in a community containing several hundred fungal species. This isopod-induced modification of community composition drove a shift in the soil enzyme profile, and led to a restructuring of the wider mycophagous invertebrate community. We highlight characteristics of different soil ecosystems that will give rise to such top-down control. Given the ubiquity of isopods and basidiomycete fungi in temperate and boreal woodland ecosystems, such top-down community control could be of widespread significance for global carbon and nutrient cycling.
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http://dx.doi.org/10.1890/13-0197.1DOI Listing
November 2013

Seasonal dynamics of fungal communities in a temperate oak forest soil.

New Phytol 2014 Jan 6;201(1):269-278. Epub 2013 Sep 6.

Institute of Microbiology of the Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, 14220, Praha 4, Czech Republic.

Fungi are the agents primarily responsible for the transformation of plant-derived carbon in terrestrial ecosystems. However, little is known of their responses to the seasonal changes in resource availability in deciduous forests, including photosynthate allocation below ground and seasonal inputs of fresh litter. Vertical stratification of and seasonal changes in fungal abundance, activity and community composition were investigated in the litter, organic and upper mineral soils of a temperate Quercus petraea forest using ergosterol and extracellular enzyme assays and amplicon 454-pyrosequencing of the rDNA-ITS region. Fungal activity, biomass and diversity decreased substantially with soil depth. The highest enzyme activities were detected in winter, especially in litter, where these activities were followed by a peak in fungal biomass during spring. The litter community exhibited more profound seasonal changes than did the community in the deeper horizons. In the litter, saprotrophic genera reached their seasonal maxima in autumn, but summer typically saw the highest abundance of ectomycorrhizal taxa. Although the composition of the litter community changes over the course of the year, the mineral soil shows changes in biomass. The fungal community is affected by season. Litter decomposition and phytosynthate allocation represent important factors contributing to the observed variations.
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http://dx.doi.org/10.1111/nph.12481DOI Listing
January 2014

Bacterial communities in tetrachloroethene-polluted groundwaters: a case study.

Sci Total Environ 2013 Jun 9;454-455:517-27. Epub 2013 Apr 9.

Laboratory of Biotransformation, Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4, Czech Republic.

The compositions of bacterial groundwater communities of three sites contaminated with chlorinated ethenes were analyzed by pyrosequencing their 16S rRNA genes. For each location, the entire and the active bacterial populations were characterized by independent molecular analysis of the community DNA and RNA. The sites were selected to cover a broad range of different environmental conditions and contamination levels, with tetrachloroethene (PCE) and trichloroethene (TCE) being the primary contaminants. Before sampling the biomass, a long-term monitoring of the polluted locations revealed high concentrations of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), which are toxic by-products of the incomplete bacterial degradation of PCE and TCE. The applied pyrosequencing technique enabled known dechlorinators to be identified at a very low detection level (<0.25%) without compromising the detailed analysis of the entire bacterial community of these sites. The study revealed that only a few species dominated the bacterial communities, with Albidiferax ferrireducens being the only highly prominent member found at all three sites. Only a limited number of OTUs with abundances of up to 1% and high sequence identities to known dechlorinating microorganisms were retrieved from the RNA pools of the two highly contaminated sites. The dechlorinating consortium was likely to be comprised of cDCE-assimilating bacteria (Polaromonas spp.), anaerobic organohalide respirers (mainly Geobacter spp.), and Burkholderia spp. involved in cometabolic dechlorination processes, together with methylotrophs (Methylobacter spp.). The deep sequencing results suggest that the indigenous dechlorinating consortia present at the investigated sites can be used as a starting point for future bioremediation activities by stimulating their anaerobic and aerobic chloroethene degradation capacities (i.e. reductive dechlorination, and metabolic and cometabolic oxidation).
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http://dx.doi.org/10.1016/j.scitotenv.2013.02.082DOI Listing
June 2013

Fungal community on decomposing leaf litter undergoes rapid successional changes.

ISME J 2013 Mar 11;7(3):477-86. Epub 2012 Oct 11.

Laboratory of Environmental Microbiology, Institute of Microbiology of the ASCR, v.v.i., Praha 4, Czech Republic.

Fungi are considered the primary decomposers of dead plant biomass in terrestrial ecosystems. However, current knowledge regarding the successive changes in fungal communities during litter decomposition is limited. Here we explored the development of the fungal community over 24 months of litter decomposition in a temperate forest with dominant Quercus petraea using 454-pyrosequencing of the fungal internal transcribed spacer (ITS) region and cellobiohydrolase I (cbhI) genes, which encode exocellulases, to specifically address cellulose decomposers. To quantify the involvement of phyllosphere fungi in litter decomposition, the fungal communities in live leaves and leaves immediately before abscission were also analysed. The results showed rapid succession of fungi with dramatic changes in the composition of the fungal community. Furthermore, most of the abundant taxa only temporarily dominated in the substrate. Fungal diversity was lowest at leaf senescence, increased until month 4 and did not significantly change during subsequent decomposition. Highly diverse community of phyllosphere fungi inhabits live oak leaves 2 months before abscission, and these phyllosphere taxa comprise a significant share of the fungal community during early decomposition up to the fourth month. Sequences assigned to the Ascomycota showed highest relative abundances in live leaves and during the early stages of decomposition. In contrast, the relative abundance of sequences assigned to the Basidiomycota phylum, particularly basidiomycetous yeasts, increased with time. Although cellulose was available in the litter during all stages of decomposition, the community of cellulolytic fungi changed substantially over time. The results indicate that litter decomposition is a highly complex process mediated by various fungal taxa.
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http://dx.doi.org/10.1038/ismej.2012.116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578564PMC
March 2013

Active and total microbial communities in forest soil are largely different and highly stratified during decomposition.

ISME J 2012 Feb 21;6(2):248-58. Epub 2011 Jul 21.

Laboratory of Environmental Microbiology, Institute of Microbiology of the ASCR, v.v.i., Vídeňská, Praha, Czech Republic.

Soils of coniferous forest ecosystems are important for the global carbon cycle, and the identification of active microbial decomposers is essential for understanding organic matter transformation in these ecosystems. By the independent analysis of DNA and RNA, whole communities of bacteria and fungi and its active members were compared in topsoil of a Picea abies forest during a period of organic matter decomposition. Fungi quantitatively dominate the microbial community in the litter horizon, while the organic horizon shows comparable amount of fungal and bacterial biomasses. Active microbial populations obtained by RNA analysis exhibit similar diversity as DNA-derived populations, but significantly differ in the composition of microbial taxa. Several highly active taxa, especially fungal ones, show low abundance or even absence in the DNA pool. Bacteria and especially fungi are often distinctly associated with a particular soil horizon. Fungal communities are less even than bacterial ones and show higher relative abundances of dominant species. While dominant bacterial species are distributed across the studied ecosystem, distribution of dominant fungi is often spatially restricted as they are only recovered at some locations. The sequences of cbhI gene encoding for cellobiohydrolase (exocellulase), an essential enzyme for cellulose decomposition, were compared in soil metagenome and metatranscriptome and assigned to their producers. Litter horizon exhibits higher diversity and higher proportion of expressed sequences than organic horizon. Cellulose decomposition is mediated by highly diverse fungal populations largely distinct between soil horizons. The results indicate that low-abundance species make an important contribution to decomposition processes in soils.
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http://dx.doi.org/10.1038/ismej.2011.95DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3260513PMC
February 2012

Ecology of coarse wood decomposition by the saprotrophic fungus Fomes fomentarius.

Biodegradation 2011 Jul 29;22(4):709-18. Epub 2010 Jul 29.

Laboratory of Environmental Microbiology, Institute of Microbiology of the ASCR, v.v.i., Vídeňská 1083, 14220, Praha 4, Czech Republic.

Saprotrophic wood-inhabiting basidiomycetes are the most important decomposers of lignin and cellulose in dead wood and as such they attracted considerable attention. The aims of this work were to quantify the activity and spatial distribution of extracellular enzymes in coarse wood colonised by the white-rot basidiomycete Fomes fomentarius and in adjacent fruitbodies of the fungus and to analyse the diversity of the fungal and bacterial community in a fungus-colonised wood and its potential effect on enzyme production by F. fomentarius. Fungus-colonised wood and fruitbodies were collected in low management intensity forests in the Czech Republic. There were significant differences in enzyme production by F. fomentarius between Betula pendula and Fagus sylvatica wood, the activity of cellulose and xylan-degrading enzymes was significantly higher in beech wood than in birch wood. Spatial analysis of a sample B. pendula log segment proved that F. fomentarius was the single fungal representative found in the log. There was a high level of spatial variability in the amount of fungal biomass detected, but no effects on enzyme activities were observed. Samples from the fruiting body showed high β-glucosidase and chitinase activities compared to wood samples. Significantly higher levels of xylanase and cellobiohydrolase were found in samples located near the fruitbody (proximal), and higher laccase and Mn-peroxidase activities were found in the distal ones. The microbial community in wood was dominated by the fungus (fungal to bacterial DNA ratio of 62-111). Bacterial abundance composition was lower in proximal than distal parts of wood by a factor of 24. These results show a significant level of spatial heterogeneity in coarse wood. One of the explanations may be the successive colonization of wood by the fungus: due to differential enzyme production, the rates of biodegradation of coarse wood are also spatially inhomogeneous.
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http://dx.doi.org/10.1007/s10532-010-9390-8DOI Listing
July 2011