Heterotrophic microorganisms in Arctic hydrothermal sediments - the ecological roles and impact of their CAZymes repertoire
Final Report Abstract
Deep-sea hydrothermal vents are among the most extreme habitats on Earth and represent targets for marine bioprospecting and biodiscovery. However, the full extent of the heterotrophic capabilities in these environments is still being explored. These habitats already constitute important environments to find new microbial solutions that are urgently needed in the bioprocessing industry, where the degradation of complex organic materials is often a major challenge. These materials include chitin, a biopolymer that has a direct impact on carbon and nitrogen cycles in the ocean. Therefore, understanding its impact on the composition and function of the diverse heterotrophic microbial community is crucial. On the other hand, the influence of synthetic polymers, like different plastic compounds, becomes more and more important in marine and especially deep-sea environments. Plastic compounds account for over 95% of the waste that is present in the world’s ocean. These polymers are extremely resistant to biodegradation e.g., because of the long-chain polymer structure, the hydrophobicity, and the crystallinity. Despite that, large numbers of microbes have been reported to degrade different types of plastic, like polyethylene terephthalate or polyurethane. But the involved mechanisms or enzymes in the degradation processes are little investigated. Due to intense and permanent deposition of plastic waste, marine environments, especially in high depths, become a target of bioprospection of microorganisms with potential to adhesion and degradation of thermoplastic resins. Deep-sea hydrothermal systems are rich in hydrocarbons found in oil and natural gas, and thus promising sites for discovery of plastic degrading microorganisms towards bioremediation for waste reduction. The conducted project deals with data of long-term and short-term in situ enrichments on chitin and various synthetic substrates, indicating responsible microorganisms and enzymes involved in the respective degradation processes. In addition to typical heterotrophic microorganisms, potential novel chitin degraders within the uncultivated candidate phylum KSB1 were identified. Metagenomic and phylogenetic investigations indicate a relationship of candidate KSB1 MAGs with MAGs assembled from the Guaymas Basin hydrothermal sediments, for which a significant role in hydrocarbon degradation was already described. By using different bioinformatical approaches various chitin degrading enzymes of the KSB1 phylum were identified. After heterologous expression and purification, the respective enzymes showed high chitin degrading activity and hence support a significant role in the carbon cycle for KSB1 bacteria. Regarding the plastic degrading approach, the material of short term in situ incubations was used as a starting point for targeted enrichments in combination with parallel long-read metagenome sequencing. By using this combined approach, various active enrichment cultures were maintained growing on different plastic substrates (polyethylene terephthalate, polyurethane, and polyethylene). The results of the project proof that plasticdegrading microorganisms were enriched in situ and identify important plastic degrading key players in deep-sea hydrothermal sediments. In addition, the identified lineages are likely adapted to dealing with the industrial substrates in the incubation chambers, and thus provide novel sources for enzyme mining.
Publications
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Insights into the chitinolytic potential of microbial communities in Arctic deep-sea hydrothermal sediments, ISME18 (Lausanne, Switzerland)
Sass, K.; Steen, I. H. & Stokke, R.
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Revealing the chitinolytic potential of microbial communities in Arctic deep-sea hydrothermal sediments, GRC Marine Microbes (Les Diablerets, Switzerland)
Sass, K.; Steen, I. H. & Stokke, R.
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Finding Mohn’s Treasure: evidence of deep hydrothermal activity at a supposedly extinct seafloor sulfide deposit. Goldschmidt2023 abstracts. European Association of Geochemistry.
Boonnawa, Chanakan; Reeves, Eoghan; Pereira, Samuel; Viflot, Thomas; Samin, Apolline; Eilertsen, Mari; Sass, Katharina; Stokke, Runar; Steen, Ida & Ribeiro, Pedro
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Heterotrophic microorganisms in Arctic hydrothermal sediments - the ecological role and impact of their CAZymes repertoire, Science by the Sea (Annual meeting of the Centre for Deep Sea Research, University of Bergen, Bergen, Norway)
Sass, K.
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Microbes from the Arctic deep ocean: A resource for plastic bioremediation, BIOPROSP2023 (Tromsø, Norway)
Sass, K.; Chow, J.; Perez Garcia, P.; Streit, W. R.; Steen, I. H. & Stokke, R.
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Microbiome reconstruction of in situ incubations reveal key players in chitin degradation in Arctic hydrothermal deep-sea sediments, FEMS2023 (Hamburg, Germany)
Sass, K.; Arsin, H.; Fedøy, A.-E.; Stokke, R. & Steen, I. H.
