Table_4_Tailoring Hydrothermal Vent Biodiversity Toward Improved Biodiscovery Using a Novel in situ Enrichment Strategy.DOCX

Deep-sea hydrothermal vents are amongst the most extreme environments on Earth and represent interesting targets for marine bioprospecting and biodiscovery. The microbial communities in hydrothermal vents are often dominated by chemolithoautotrophs utilizing simple chemical compounds, though the full extent of their heterotrophic abilities is still being explored. In the bioprocessing industry, where degradation of complex organic materials often is a major challenge, new microbial solutions are heavily needed. To meet these needs, we have developed novel in situ incubators and tested if deployment of recalcitrant materials from fish farming and wood-pulping industries introduced changes in the microbial community structure in hot marine hydrothermal sediments. The incubation chambers were deployed in sediments at the Bruse vent site located within the Jan Mayen vent field for 1 year, after which the microbial populations in the chambers were profiled by 16S rRNA Ion Torrent amplicon sequencing. A total of 921 operational taxonomic units (OTUs) were assigned into 74 different phyla where differences in community structure were observed depending on the incubated material, chamber depth below the sea floor and/or temperature. A high fraction of putative heterotrophic microbial lineages related to cultivated members within the Thermotogales were observed. However, considerable fractions of previously uncultivated and novel Thermotogales and Bacteroidetes were also identified. Moreover, several novel lineages (e.g., members within the DPANN superphylum, unidentified archaeal lineages, unclassified Thermoplasmatales and Candidatus division BRC-1 bacterium) of as-yet uncultivated thermophilic archaea and bacteria were identified. Overall, our data illustrate that amendment of hydrothermal vent communities by in situ incubation of biomass induces shifts in community structure toward increased fractions of heterotrophic microorganisms. The technologies utilized here could aid in subsequent metagenomics-based enzyme discovery for diverse industries.

深海热液喷口（deep-sea hydrothermal vents）是地球上最为极端的环境之一，同时也是海洋生物勘探与生物发现的重要研究靶点。热液喷口的微生物群落通常以化能自养微生物（chemolithoautotrophs）为优势类群，这类微生物利用简单的化学物质获取能量，但目前学界仍在探索这类微生物异养功能的完整范围。在生物加工产业中，复杂有机物质的降解往往是核心难题，因此亟需新型微生物解决方案。为满足这一需求，本研究开发了新型原位培养装置（in situ incubators），并针对水产养殖与木材制浆产业产生的难降解物料进行部署，以此探究其对高温海洋热液沉积物中微生物群落结构的影响。本研究将培养舱部署于扬马延热液田内的布吕瑟（Bruse）喷口位点的沉积物中，培养周期为1年，随后通过16S rRNA Ion Torrent扩增子测序对培养舱内的微生物种群进行群落解析。本次测序共得到921个操作分类单元（operational taxonomic units, OTUs），这些单元被归类至74个不同的菌门；研究观察到，微生物群落结构的差异取决于所培养的底物、培养舱距海底的深度以及/或环境温度。研究观察到大量与已培养的热袍菌目（Thermotogales）物种相关的疑似异养微生物类群，但同时也鉴定出相当比例的此前未被培养的新型热袍菌目与拟杆菌门（Bacteroidetes）类群。此外，本研究还鉴定出多个尚未被培养的嗜热古菌与细菌的新型类群，例如DPANN超门（DPANN superphylum）内的类群、未鉴定的古菌谱系、未分类的热原体目（Thermoplasmatales）以及候选门BRC-1细菌（Candidatus division BRC-1 bacterium）。综合来看，本研究数据表明，通过原位培养生物质对热液喷口群落进行干预，可促使群落结构向异养微生物占比提升的方向转变。本研究所使用的技术可为后续基于宏基因组学（metagenomics）的各类产业用酶发现工作提供助力。