基于碳代谢的化能自养硫氧化细菌与化能异养细菌的相互作用

Interactions between chemolithoautotrophic sulfur-oxidizing bacteria and chemoheterotrophic bacteria based on carbon metabolism

摘要:

目的 从碳代谢角度分析化能自养硫氧化细菌与化能异养细菌共培养时的相互促进作用机制。方法 采用离子色谱测定S₂O₃^2-和SO₄^2-浓度，平板稀释涂布法跟踪菌体生长情况，利用总有机碳测定仪和液相色谱-质谱分析胞外碳特性，扫描电镜观察细胞形态，RT-qPCR测定相关基因表达量。结果 硫氧化细菌在生长过程中持续固碳，为异养细菌生长提供稳定碳源；异养细菌显著促进了硫氧化细菌的硫氧化和固碳能力，硫氧化酶基因soxB和碳固定RubisCO酶基因cbbL表达量显著增加；同时诱导产生更多的胞外聚合物，增强整体生物膜的形成。结论 本研究揭示了硫氧化细菌与异养细菌之间的协同作用机制，特别是异养细菌对硫氧化细菌固碳能力的显著促进作用。为化能自养细菌的富集培养及理解微生物群落中自养硫氧化细菌的固碳机制提供了新的视角，并为废水处理的低碳化和高效化提供了理论支持。

Abstract:

Objective To study the mechanisms of mutual promotion between chemolithoauto-trophic sulfur-oxidizing bacteria and chemoheterotrophic bacteria under co-culture based on carbon metabolism.Methods Ion chromatography was employed to determine the concentrations of S₂O₃^2? (thiosulfate) and SO₄^2? (sulfate). Bacterial growth dynamics were monitored by the dilution plate method. Extracellular carbon characteristics were analyzed via total organic carbon analyzer measurement and LC-MS. Cellular morphology was observed by scanning electron microscopy. The relative mRNA levels of related genes were quantified by RT-qPCR.Results During the growth process, sulfur-oxidizing bacteria continuously fixed inorganic carbon and secreted organics, providing a stable carbon source for the growth of heterotrophic bacterium. In return, heterotrophic bacteria significantly enhanced the sulfur-oxidizing and carbon-fixing capabilities of sulfur-oxidizing bacteria. This was evidenced by the significantly up-regulated expression of the enzyme gene soxB involved in sulfur oxidation and the RubisCO gene cbbL involved in carbon fixation. Additionally, the production of extracellular polymeric substances was induced, which enhanced the biofilm formation.Conclusion This study elucidated the interaction mechanisms between sulfur-oxidizing bacteria and heterotrophic bacteria, particularly the significant enhancement of the carbon-fixing capability of sulfur-oxidizing bacteria. The findings provide a new perspective for the enrichment culture of chemolithoautotrophic bacteria and for understanding the carbon fixation mechanisms of autotrophic sulfur-oxidizing bacteria in microbial communities. Additionally, this study offers theoretical support for the low-carbon and efficient treatment of wastewater.