Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen 518055, Guangdong, China.
Key Laboratory of Microorganism Application and Risk Control (MARC) of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong, China.
Environ Int. 2020 May;138:105650. doi: 10.1016/j.envint.2020.105650. Epub 2020 Mar 14.
Interspecies electron transfer plays an important role in syntrophic methanogenesis. Direct interspecies electron transfer (DIET) between syntrophic oxidizers and methanogens via conductive pili has been only confirmed in some specific co-cultures. This study examined potential syntrophic cooperation via type IV pili and quorum sensing between widespread syntrophic bacteria and methanogens through a metagenomic analysis of 12 anaerobic sludge samples. We found that Methanosaeta and Methanosarcina, which are reported to have DIET ability, were dominant in most methanogenic samples. Putative conductive pili genes were found in some typical syntrophic bacteria, which has rarely been reported previously. The existence of diverse quorum-sensing genes suggested that various quorum-sensing systems might participate in the communication of anaerobic microorganisms. Specifically, the diffusible signal factor and 3'-5' cyclic diguanosine monophosphate related genes were mainly assigned to syntrophic bacteria. These results suggest that the combined regulation of these signals might be responsible for the biosynthesis of type IV pili and affect syntrophic interaction during methanogenesis. These novel results provide fresh evidence to support the widespread existence of DIET in anaerobic methanogenic systems; therefore, regulating the quorum-sensing system may promote syntrophic interaction.
种间电子传递在共代谢产甲烷中起着重要作用。通过导电菌毛在共氧化还原体和产甲烷菌之间进行的直接种间电子传递 (DIET) 仅在一些特定的共培养物中得到证实。本研究通过对 12 个厌氧污泥样本的宏基因组分析，研究了通过 IV 型菌毛和群体感应在广泛存在的共代谢细菌和产甲烷菌之间可能存在的共代谢合作。我们发现，据报道具有 DIET 能力的 Methanosaeta 和 Methanosarcina 在大多数产甲烷样本中占优势。在一些典型的共代谢细菌中发现了假定的导电菌毛基因，这在以前很少有报道。存在多种群体感应基因表明各种群体感应系统可能参与厌氧微生物的通讯。具体而言，扩散信号因子和 3'-5' 环二鸟苷酸单磷酸相关基因主要分配给共代谢细菌。这些结果表明，这些信号的综合调节可能负责 IV 型菌毛的生物合成，并影响产甲烷过程中的共代谢相互作用。这些新的结果为支持厌氧产甲烷系统中广泛存在 DIET 提供了新的证据；因此，调节群体感应系统可能会促进共代谢相互作用。
