About the Speaker: Petr Baldrian, Head Laboratory of Enviromental Microbiology, Institute of Microbiology, Prague
Petr Baldrian is the head of the Laboratory of Environmental Microbiology of the Institute of Microbiology in Prague. He has graduated in Microbiology from the Faculty of Science, Charles University, Prague where he now teaches Microbial ecology, Microbial processes in the environment and Geomicrobiology. His research focuses the importance of microorganisms – fungi and bacteria – in the ecosystem processes especially in forest ecosystems, their involvement in the turnover of organic compounds and interactions with other organisms. Another topic is the application of environmental microbial strains in biotechnology. He is the author or co-author of 140 papers (ResearchGate).
About the Presentation: Microbes in forest soils: tracing the activity of communities and individual taxa
In forest soils, microbes are important drivers of soil processes, because they mediate decomposition as well as nutrient transfer from primary producers into soil. Metatranscriptomics, metaproteomics and enzyme activity assays that can assess the dynamics of microbial processes and assign functions to higher taxa show that microbial activity undergoes seasonal cycling with a fungal dominance in summer and bacterial dominance in winter affecting multiple processes ranging from ectomycorrhizal symbiosis to decomposition1. The results characterize the summer season as a period with rapid microbial growth accompanied by decomposition of recalcitrant plant biopolymers likely induced by the priming effect of photosynthates delivered by plant roots. Winter appears to be a period of slow growth when reserve compounds such as starch, glycogen and trehalose are utilized. Methods focusing environmental metacommunities are, however, not able to identify individual microbial species, participating in the soil processes. To do that, individual microbial taxa need to be isolated and analyzed. Genomes of 20 dominant bacterial strains from the spruce forest soil were sequenced as well as genomes of ectomycorrhizal fungi, obtained from fruitbodies collected at the study sites. Mapping of metatranscriptomic reads on genomes of dominant bacteria showed, interestingly, that Acidobacteria are the likely major producers of decomposition-related enzymes that possess high counts of glycosyl hydrolases in their genomes, in contrast to Bacteroidetes and Proteobacteria. Transcript profiles of bacteria and fungi in situ differ among horizons as well as among seasons showing the effect of environmental conditions on transcription.
1 Žifčáková L, Větrovský T, Howe A, Baldrian P. 2016. Microbial activity in forest soil reflects the changes in ecosystem properties between summer and winter. Environmental Microbiology 18:288-301.