Key Laboratory of Coastal Biology and Biological Resources Utilization, CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, PR China.
Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, 518060, PR China.
Water Res. 2021 Sep 1;202:117490. doi: 10.1016/j.watres.2021.117490. Epub 2021 Aug 1.
Geobacter, as a typical electroactive microorganism, is the "engine" of interspecies electron transfer (IET) between microorganisms. However, it does not have a dominant position in all natural environments. It is not known what performs a similar function as Geobacter in coastal zones. Metagenomic and metatranscriptomic analysis revealed that Desulfovibrio and Methanobacterium species were the most abundant in electrochemically active aggregates. Metatranscriptomic analysis showed that Desulfovibrio species highly expressed genes for ethanol metabolism and extracellular electron transfer involving cytochromes, pili and flagella. Methanobacterium species in the aggregates also expressed genes for enzymes involved in reducing carbon dioxide to methane. Pure cultures demonstrated that the isolated Desulfovibrio sp. strain JY contributed to aggregate conductivity and directly transferred electrons to Methanothrix harundinacea, which is unable to use H or formate. Most importantly, further coculture studies indicated that Methanobacterium strain YSL might directly accept electrons from the Desulfovibrio strain JY for the reduction of carbon dioxide to methane in the aggregate. This finding suggested that the possibility of DIET by Desulfovibrio similar to Geobacter species in conductive methanogenic aggregates can not be excluded.
作为一种典型的电活性微生物，地杆菌是微生物间电子转移（IET）的“引擎”。然而，它在所有自然环境中并不占据主导地位。目前还不清楚在沿海地区有什么微生物可以像地杆菌一样发挥类似的作用。宏基因组和宏转录组分析表明，脱硫弧菌属和产甲烷杆菌属在电化学活性聚集体中最为丰富。宏转录组分析表明，脱硫弧菌属高度表达涉及细胞色素、菌毛和鞭毛的乙醇代谢和细胞外电子转移的基因。聚集体中的产甲烷杆菌属也表达了参与将二氧化碳还原为甲烷的酶的基因。纯培养实验表明，分离得到的脱硫弧菌 JY 菌株有助于聚集体的导电性，并直接将电子传递给无法利用 H 或甲酸盐的产甲烷菌 Harundinacea。最重要的是，进一步的共培养研究表明，产甲烷杆菌 YSL 菌株可能直接从脱硫弧菌 JY 菌株接受电子，用于在聚集体中将二氧化碳还原为甲烷。这一发现表明，在导电产甲烷聚集体中，类似于地杆菌属的脱硫弧菌属可能通过直接电子传递（DIET）。
