Chan Jiulin, Geng Daoqiang, Pan Binbin, Zhang Qiming, Xu Qianghua
Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai, China.
Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China.
Front Microbiol. 2021 Jun 7;12:668989. doi: 10.3389/fmicb.2021.668989. eCollection 2021.
Hadal trenches are the deepest known areas of the ocean. Amphipods are considered to be the dominant scavengers in the hadal food webs. The studies on the structure and function of the hadal intestinal microbiotas are largely lacking. Here, the intestinal microbiotas of three hadal amphipods, , , and , from Mariana Trench, Marceau Trench, and New Britain Trench, respectively, were investigated. The taxonomic analysis identified 358 microbial genera commonly shared within the three amphipods. Different amphipod species possessed their own characteristic dominant microbial component, in and in and . Functional composition analysis showed that "Carbohydrate Metabolism," "Lipid Metabolism," "Cell Motility," "Replication and Repair," and "Membrane Transport" were among the most represented Gene Ontology (GO) Categories in the gut microbiotas. To test the possible functions of "Bacterial Chemotaxis" within the "Cell Motility" category, the methyl-accepting chemotaxis protein () gene involved in the "Bacterial Chemotaxis" pathway was obtained and used for swarming motility assays. Results showed that bacteria transformed with the gut bacterial gene showed significantly faster growths compared with the control group, suggesting MCP promoted the bacterial swimming capability and nutrient utilization ability. This result suggested that hadal gut microbes could promote their survival in poor nutrient conditions by enhancing chemotaxis and motility. In addition, large quantities of probiotic genera were detected in the hadal amphipod gut microbiotas, which indicated that those probiotics would be possible contributors for promoting the host's growth and development, which could facilitate adaptation of hadal amphipods to the extreme environment.
超深渊海沟是已知海洋中最深的区域。端足类动物被认为是超深渊食物网中的主要食腐动物。目前对超深渊肠道微生物群的结构和功能研究还很缺乏。在此，分别对来自马里亚纳海沟、马尔索海沟和新不列颠海沟的三种超深渊端足类动物（、和）的肠道微生物群进行了研究。分类分析确定了这三种端足类动物共有的358个微生物属。不同的端足类物种拥有各自独特的优势微生物组成，在中为，在和中为。功能组成分析表明，“碳水化合物代谢”“脂质代谢”“细胞运动”“复制与修复”和“膜运输”是肠道微生物群中最具代表性的基因本体（GO）类别。为了测试“细胞运动”类别中“细菌趋化性”的可能功能，获得了参与“细菌趋化性”途径的甲基接受趋化蛋白（）基因，并用于群体运动分析。结果表明，与对照组相比，用肠道细菌基因转化的细菌生长明显更快，这表明MCP促进了细菌的游泳能力和营养利用能力。这一结果表明，超深渊肠道微生物可以通过增强趋化性和运动能力来促进它们在营养条件差的环境中的生存。此外，在超深渊端足类动物肠道微生物群中检测到大量益生菌属，这表明这些益生菌可能有助于促进宿主的生长发育，从而有助于超深渊端足类动物适应极端环境。
