[ { "id": "authors:yfhek-6q694", "collection": "authors", "collection_id": "yfhek-6q694", "cite_using_url": "https://authors.library.caltech.edu/records/yfhek-6q694", "type": "monograph", "title": "Deep sea anaerobic microbial community couples the degradation of insoluble chitin to extracellular electron transfer", "author": [ { "family_name": "Jangir", "given_name": "Yamini", "orcid": "0000-0002-2779-9049", "clpid": "Jangir-Yamini" }, { "family_name": "Guo", "given_name": "Yongzhao", "orcid": "0009-0005-3983-8382", "clpid": "Guo-Yongzhao" }, { "family_name": "Connon", "given_name": "Stephanie", "clpid": "Connon-Stephanie-A" }, { "family_name": "Pontrelli", "given_name": "Sammy", "orcid": "0000-0001-6265-8842" }, { "family_name": "Wu", "given_name": "Fabai", "orcid": "0000-0001-5812-5621", "clpid": "Wu-Fabai" }, { "family_name": "Schwartzman", "given_name": "Julia", "orcid": "0000-0003-4563-4835" }, { "family_name": "Lim", "given_name": "Sujung", "orcid": "0000-0001-6040-729X", "clpid": "Lim-Sujung" }, { "family_name": "Sauer", "given_name": "Uwe", "orcid": "0000-0002-5923-0770" }, { "family_name": "Cordero", "given_name": "Otto X.", "orcid": "0000-0002-2695-270X" }, { "family_name": "Orphan", "given_name": "Victoria J.", "orcid": "0000-0002-5374-6178", "clpid": "Orphan-V-J" } ], "abstract": "

Chitin is a major structural component of arthropod exoskeletons, and an important carbon and nitrogen source in marine environments. In anoxic sediments, its degradation generates chitooligosaccharides and N-acetylglucosamine (GlcNAc), which are fermented into smaller organic molecules and oxidized anaerobically using soluble electron acceptors or insoluble ones such as metal oxides. To date, many aspects of chitin degradation in deep-sea anoxic sediments have been overlooked, including the potential coupling of insoluble chitin degradation to metal oxide reduction, the involvement of extracellular electron transfer (EET), and the spatial organization of the microorganisms involved. Using anoxic deep-sea sediments recovered from a whale fall site, we developed an innovative workflow based on electrochemical reactors, to characterize chitin degradation in these environments. Sediment samples enriched on poorly crystalline iron oxides, and subsequently transferred into an electrochemical reactor poised at +0.22 V vs SHE, showed active anodic current production when supplied with chitin, which increased 2-fold when amended with GlcNAc. Chitin reactors were dominated byVallitalea(Firmicutes),Spirochaetota,GammaproteobacteriaandDesulfobacterota. Exoenzyme activity assays, metabolite profiling, and continued anodic current production confirmed ongoing chitin degradation linked to EET. We observed metabolic associations between chitin degraders and secondary consumers usingin situimaging (16S rRNA gene FISH coupled with BONCAT and nanoSIMS). These microbial partners, within the electrode-attached community, required close proximity to the poised electrode (≤ 10 µm) to remain metabolically active. Supporting these observations, cultured isolates ofVallitaleasp. andTrichloromonassp. recovered from the whale fall site exhibited chitin degradation and electrochemical activity, respectively. When co-cultured in an bioelectrochemical reactor, the acetate produced byVallitaleasp. during chitin degradation fueledTrichloromonassp., which facilitated EET, hereby demonstrating that syntrophic interactions are used to couple anoxic chitin degradation to EET in deep-sea sediments. These findings exemplify the interspecies interactions and resource optimization occurring in hard-to-reach and largely unknown deep-sea ecosystems.

", "doi": "10.1101/2025.06.30.662270", "publisher": "bioRxiv", "publication_date": "2025-06-30" }, { "id": "authors:ddbgb-8jb47", "collection": "authors", "collection_id": "ddbgb-8jb47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210804-220359405", "type": "monograph", "title": "Microbial community of recently discovered Auka vent field sheds light on vent biogeography and evolutionary history of thermophily", "author": [ { "family_name": "Speth", "given_name": "Daan R.", "orcid": "0000-0002-2361-5935", "clpid": "Speth-Daan-R" }, { "family_name": "Yu", "given_name": "Feiqiao B.", "orcid": "0000-0003-3416-3046", "clpid": "Yu-Feiqiao-B" }, { "family_name": "Connon", "given_name": "Stephanie A.", "clpid": "Connon-Stephanie-A" }, { "family_name": "Lim", "given_name": "Sujung", "orcid": "0000-0001-6040-729X", "clpid": "Lim-Sujung" }, { "family_name": "Magyar", "given_name": "John S.", "orcid": "0000-0002-3586-8286", "clpid": "Magyar-John-S" }, { "family_name": "Pe\u00f1a", "given_name": "Manet E.", "orcid": "0000-0002-5835-0455", "clpid": "Pe\u00f1a-Manet-E" }, { "family_name": "Quake", "given_name": "Stephen R.", "orcid": "0000-0002-1613-0809", "clpid": "Quake-Stephen-R" }, { "family_name": "Orphan", "given_name": "Victoria J.", "orcid": "0000-0002-5374-6178", "clpid": "Orphan-V-J" } ], "abstract": "Hydrothermal vents have been key to our understanding of the limits of life, and the metabolic and phylogenetic diversity of thermophilic organisms. Here we used environmental metagenomics combined with analysis of physico-chemical data and 16S rRNA amplicons to characterize the diversity, temperature optima, and biogeographic distribution of sediment-hosted microorganisms at the recently discovered Auka vents in the Gulf of California, the deepest known hydrothermal vent field in the Pacific Ocean. We recovered 325 metagenome assembled genomes (MAGs) representing 54 phyla, over 1/3 of the currently known phylum diversity, showing the microbial community in Auka hydrothermal sediments is highly diverse. Large scale 16S rRNA amplicon screening of 227 sediment samples across the vent field indicates that the MAGs are largely representative of the microbial community. Metabolic reconstruction of a vent-specific, deeply branching clade within the Desulfobacterota (Tharpobacteria) suggests these organisms metabolize sulfur using novel octaheme cytochrome-c proteins related to hydroxylamine oxidoreductase. Community-wide comparison of the average nucleotide identity of the Auka MAGs with MAGs from the Guaymas Basin vent field, found 400 km to the Northwest, revealed a remarkable 20% species-level overlap between vent sites, suggestive of long-distance species transfer and sediment colonization. An adapted version of a recently developed model for predicting optimal growth temperature to the Auka and Guaymas MAGs indicates several of these uncultured microorganisms could grow at temperatures exceeding the currently known upper limit of life. Extending this analysis to reference data shows that thermophily is a trait that has evolved frequently among Bacteria and Archaea. Combined, our results show that Auka vent field offers new perspectives on our understanding of hydrothermal vent microbiology.", "doi": "10.1101/2021.08.02.454472", "publication_date": "2021-08-03" } ]