Metamenu

  • Centre for Microbiology and Environmental Systems Science

  • CUBE - Computational Systems Biology

  • DOME - Microbial Ecology

  • EDGE - Environmental Geosciences

  • TER - Terrestrial Ecosystem Research

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Latest publications

Anaerobic bacterial degradation of protein and lipid macromolecules in subarctic marine sediment

Microorganisms in marine sediments play major roles in marine biogeochemical cycles by mineralizing substantial quantities of organic matter from decaying cells. Proteins and lipids are abundant components of necromass, yet the taxonomic identities of microorganisms that actively degrade them remain poorly resolved. Here, we revealed identities, trophic interactions and genomic features of bacteria that degraded 13C-labelled proteins and lipids in cold anoxic microcosms containing sulfidic subarctic marine sediment. Supplemented proteins and lipids were rapidly fermented to various volatile fatty acids within five days. DNA-stable isotope probing (SIP) suggested Psychrilyobacter atlanticus was an important primary degrader of proteins, and Psychromonas members were important primary degraders of both proteins and lipids. Closely related Psychromonas populations, as represented by distinct 16S rRNA gene variants, differentially utilized either proteins or lipids. DNA-SIP also showed 13C-labeling of various Deltaproteobacteria within ten days, indicating trophic transfer of carbon to putative sulfate-reducers. Metagenome-assembled genomes revealed the primary hydrolyzers encoded secreted peptidases or lipases, and enzymes for catabolism of protein or lipid degradation products. Psychromonas species are prevalent in diverse marine sediments, suggesting they are important players in organic carbon processing in situ. Together, this study provides new insights into the identities, functions and genomes of bacteria that actively degrade abundant necromass macromolecules in the seafloor.

Pelikan C, Wasmund K, Glombitza C, Hausmann H, Herbold CW, Flieder M, Loy A
2020 - ISME J, In press

Rational design of a microbial consortium of mucosal sugar utilizers reduces Clostridiodes difficile colonization.

Many intestinal pathogens, including Clostridioides difficile, use mucus-derived sugars as crucial nutrients in the gut. Commensals that compete with pathogens for such nutrients are therefore ecological gatekeepers in healthy guts, and are attractive candidates for therapeutic interventions. Nevertheless, there is a poor understanding of which commensals use mucin-derived sugars in situ as well as their potential to impede pathogen colonization. Here, we identify mouse gut commensals that utilize mucus-derived monosaccharides within complex communities using single-cell stable isotope probing, Raman-activated cell sorting and mini-metagenomics. Sequencing of cell-sorted fractions reveals members of the underexplored family Muribaculaceae as major mucin monosaccharide foragers, followed by members of Lachnospiraceae, Rikenellaceae, and Bacteroidaceae families. Using this information, we assembled a five-member consortium of sialic acid and N-acetylglucosamine utilizers that impedes C. difficile's access to these mucosal sugars and impairs pathogen colonization in antibiotic-treated mice. Our findings underscore the value of targeted approaches to identify organisms utilizing key nutrients and to rationally design effective probiotic mixtures.

Pereira FC, Wasmund K, Cobankovic I, Jehmlich N, Herbold CW, Lee KS, Sziranyi B, Vesely C, Decker T, Stocker R, Warth B, von Bergen M, Wagner M, Berry D
2020 - Nat Commun, 1: 5104

Genomic and kinetic analysis of novel Nitrospinae enriched by cell sorting

Chemolithoautotrophic nitrite-oxidizing bacteria (NOB) are key players in global nitrogen and carbon cycling. Members of the phylum Nitrospinae are the most abundant, known NOB in the oceans. To date, only two closely affiliated Nitrospinae species have been isolated, which are only distantly related to the environmentally abundant uncultured Nitrospinae clades. Here, we applied live cell sorting, activity screening, and subcultivation on marine nitrite-oxidizing enrichments to obtain novel marine Nitrospinae. Two binary cultures were obtained, each containing one Nitrospinae strain and one alphaproteobacterial heterotroph. The Nitrospinae strains represent two new genera, and one strain is more closely related to environmentally abundant Nitrospinae than previously cultured NOB. With an apparent half-saturation constant of 8.7±2.5 µM, this strain has the highest affinity for nitrite among characterized marine NOB, while the other strain (16.2±1.6 µM) and Nitrospina gracilis (20.1±2.1 µM) displayed slightly lower nitrite affinities. The new strains and N. gracilis share core metabolic pathways for nitrite oxidation and CO2 fixation but differ remarkably in their genomic repertoires of terminal oxidases, use of organic N sources, alternative energy metabolisms, osmotic stress and phage defense. The new strains, tentatively named “Candidatus Nitrohelix vancouverensis” and “Candidatus Nitronauta litoralis”, shed light on the niche differentiation and potential ecological roles of Nitrospinae.

Mueller AJ, Jung MY, Strachan CR, Herbold CW, Kirkegaard RH, Wagner M, Daims H
2020 - ISME J., in press

Lecture series

Exploring early life microbiota dynamics

Lindsay Hall
Technical University of Munich
29.10.2020
12:00 h
Webinar

Speleothems and Sediments as Archives for Paleogenetic Research on Human Evolution

Dr. Mareike Stahlschmidt
Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Germany
12.11.2020
17:00 h
Online

Photochemically produced halogen radicals: contaminant degradation, organic matter bleaching and coral death

Prof. Dr. William Mitch
Civil and Environmental Engineering, Stanford University, US
19.11.2020
17:00 h
Online