Zeng Xiang, Chen Jianwei, Liu Guilin, Zhou Yadong, Wang Liping, Zhang Yaolei, Liu Shanshan, Shao Zongze
Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China.
Faculty of Marine Biology, Xiamen Ocean Vocational College, Xiamen 361100, China.
Biology (Basel). 2025 Jul 29;14(8):954. doi: 10.3390/biology14080954.
Snails at hydrothermal vents rely on symbiotic bacteria for nutrition; however, the specifics of these associations in adapting to such extreme environments remain underexplored. This study investigated the community structure and metabolic potential of bacteria associated with two Indian Ocean vent snails, and . Using microscopic, phylogenetic, and metagenomic analyses, this study examines bacterial communities inhabiting the foot and gland tissues of these snails. exhibited exceptionally low bacterial diversity (Shannon index 0.14-0.18), primarily Gammaproteobacteria (99.9%), including chemosynthetic sulfur-oxidizing Chromatiales using Calvin-Benson-Bassham cycle and methane-oxidizing Methylococcales in the glands. hosted significantly more diverse symbionts (Shannon indices 1.32-4.60). Its black variety scales were dominated by Campylobacterota (67.01-80.98%), such as , which perform sulfur/hydrogen oxidation via the reductive tricarboxylic acid cycle, with both Campylobacterota and Gammaproteobacteria prevalent in the glands. The white-scaled variety of had less Campylobacterota but a higher diversity of heterotrophic bacteria, including Delta-/Alpha-Proteobacteria, Bacteroidetes, and Firmicutes (classified as Desulfobacterota, Pseudomomonadota, Bacteroidota, and in GTDB taxonomy). In , Gammaproteobacteria, including Chromatiales, Thiotrichales, and a novel order "Endothiobacterales," were chemosynthetic, capable of oxidizing sulfur, hydrogen, or iron, and utilizing the Calvin-Benson-Bassham cycle for carbon fixation. Heterotrophic Delta- and Alpha-Proteobacteria, Bacteroidetes, and Firmicutes potentially utilize organic matter from protein, starch, collagen, amino acids, thereby contributing to the holobiont community and host nutrition accessibility. The results indicate that host species and intra-species variation, rather than the immediate habitat, might shape the symbiotic microbial communities, crucial for the snails' adaptation to vent ecosystems.
热液喷口处的蜗牛依靠共生细菌获取营养；然而，这些共生关系在适应如此极端环境方面的具体情况仍未得到充分研究。本研究调查了与两种印度洋喷口蜗牛相关的细菌群落结构和代谢潜力。通过显微镜、系统发育和宏基因组分析，本研究检测了栖息在这些蜗牛足部和腺体组织中的细菌群落。[蜗牛名称1]的细菌多样性极低（香农指数为0.14 - 0.18），主要是γ-变形菌纲（99.9%），包括在腺体中利用卡尔文-本森-巴斯姆循环进行化学合成的硫氧化色杆菌目和甲烷氧化甲基球菌目。[蜗牛名称2]的共生体种类要丰富得多（香农指数为1.32 - 4.60）。其黑色变种鳞片以弯曲杆菌门（67.01 - 80.98%）为主，例如[具体菌名]，它们通过还原性三羧酸循环进行硫/氢氧化，弯曲杆菌门和γ-变形菌纲在腺体中都很常见。[蜗牛名称2]白色鳞片变种的弯曲杆菌门较少，但异养细菌的多样性较高，包括δ-/α-变形菌纲、拟杆菌门和厚壁菌门（在GTDB分类法中分类为脱硫杆菌门、假单胞菌门、拟杆菌门和[具体菌名]）。在[蜗牛名称1]中，包括色杆菌目、硫发菌目和一个新目“内硫杆菌目”在内的γ-变形菌纲具有化学合成能力，能够氧化硫、氢或铁，并利用卡尔文-本森-巴斯姆循环进行碳固定。异养的δ-和α-变形菌纲、拟杆菌门和厚壁菌门可能利用来自蛋白质、淀粉、胶原蛋白、氨基酸的有机物，从而对共生生物群落和宿主的营养获取做出贡献。结果表明，宿主物种和种内变异，而非直接的栖息地，可能塑造了共生微生物群落，这对蜗牛适应喷口生态系统至关重要。
