Heterotrophic microorganisms in Arctic hydrothermal sediments - the ecological roles and impact of their CAZymes repertoire

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Deep-sea hydrothermal vents are among the most extreme habitats on Earth and represent interesting targets for marine bioprospecting and biodiscovery. Microbial communities at deep-sea hydrothermal vents are often dominated by chemolithoautotrophic microorganisms that use simple chemical compounds as energy sources. However, the full extent of their heterotrophic capabilities is still being explored. New microbial solutions are urgently needed in the bioprocessing industry, where the degradation of complex organic materials is often a major challenge. To meet these needs, novel in situ incubators have already been developed and tested to see if the use of degradation-resistant materials from the wood processing industry causes changes in the microbial community structure in hot marine hydrothermal sediments. Differences in the microbial community structure were observed depending on the used material, chamber depth below the seafloor, and/or temperature. 16S rRNA amplicon sequencing revealed a high proportion of heterotrophic microbial lineages related to cultivated members within the Thermotogales. However, significant proportions of previously uncultured and novel Thermotogales and Bacteroidetes were also identified. In addition, several new lineages of not yet cultured thermophilic Archaea and Bacteria were observed. Based on this, the goal of the proposed project is to cultivate and isolate various heterotrophic bacteria from Arctic hydrothermal sediments. Enrichment cultures with different substrates such as cellulose and chitin will be screened for the presence of polysaccharide degrading enzymes identified in already available metagenomes. Targeted cultivation strategies will be performed to select the new heterotrophic bacteria. Genomic analyses for different metabolic capacities will support these. Functional analyses at the single cell level will help identify and isolate the target bacteria based on their in situ activity in mixed cultures. Finally, novel heterotrophic bacteria will be characterized in detail with respect to morphology, physiology and their genome. Metatranscriptomic approaches under modified incubation conditions will also provide information about the carbohydrate-active enzymes (CAZymes). These will be investigated and characterized in more detail. Thus, based on metagenomes and metatranscriptomes, new enzymes for various industries can be discovered. The metabolic secrets and the capacity of the microbiomes of hydrothermal vents in the Arctic deep-sea will be revealed within this project.