Ca. Thiodiazotropha symbionts of the deep-sea lucinid clam Lucinoma kazani are metabolically versatile.

The goal of this study was to identify the key functions of Candidatus Thiodiazotropha gloverae symbionts that are hosted in the gills of the lucinind clams, Lucinoma kazani, found at the deep-sea hydrocarbon seeps in the eastern Mediterranean Sea. These symbionts (Cromatiales, Sedimenticolaceae) are chemoautotrophs that use sulfide and thiosulfate as electron donors, and oxygen or nitrate as electron acceptors to fuel energy conservation. Yet, Ca. Thiodiazotropha gloverae ex. Lucinoma kazani can use alternative energy sources, such as methanol and formate. These symbionts encode the metabolic potential for dinitrogen fixation. In April 2021, we collected four L. kazani specimens near a brine pool in Palmahim Disturbance offshore Israel at a water depth of approximately 1150 m, (32° 13' 23.5" N 34° 10' 42.19" E), using a remotely-operated vehicle. They were fixed in RNAlater, which was discarded after 24 hours, and the specimens were kept at -80°C until DNA/RNA/protein co-extraction using the AllPrep DNA/RNA/Protein Mini Kit (Cat. No. 80004, Qiagen).

本研究旨在明确寄生于东地中海深海烃类冷泉中发现的路西诺马蛤（Lucinoma kazani）鳃组织内的候选硫固氮菌格洛弗氏共生体（Candidatus Thiodiazotropha gloverae）的核心功能。该类共生体隶属于着色菌目（Chromatiales）、沉积物杆菌科（Sedimenticolaceae），为化能自养菌，以硫化物与硫代硫酸盐作为电子供体，以氧气或硝酸盐作为电子受体以维系能量代谢。然而，分离自路西诺马蛤的候选硫固氮菌格洛弗氏共生体可利用甲醇、甲酸盐等替代能源。这类共生体具备生物固氮的代谢潜能。2021年4月，我们借助遥控水下机器人，在以色列近海帕拉希姆扰动区一处盐水池附近（水深约1150米，坐标32°13′23.5″N 34°10′42.19″E）采集了4只路西诺马蛤标本。标本先用RNAlater固定，24小时后弃去该保存液，随后将标本置于-80℃环境保存，直至使用货号为80004的AllPrep DNA/RNA/蛋白微量提取试剂盒（Qiagen）完成DNA、RNA与蛋白的共提取。