Zhao Chen, Zhang Chunchun, Shen Zhiqiang, Yang Yanping, Qiu Zhigang, Li Chenyu, Xue Bin, Zhang Xi, Yang Xiaobo, Wang Shang, Wang Jingfeng
Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin, China.
School of Environmental Science Engineering, Tiangong University, Tianjin, China.
AMB Express. 2022 Mar 25;12(1):39. doi: 10.1186/s13568-022-01380-3.
Here a stable glycogen accumulating organisms (GAOs) system was operated by anaerobic-aerobic mode in the sequencing batch reactor. We focused on the metabolic mechanisms of PHAs storage from GAOs. Our system showed the classic characteristic of glycogen accumulating metabolism (GAM). Glycogen consumption was followed by acetic acid uptake to synthesize poly-β-hydroxyalkanoates (PHAs) during the anaerobic period, and glycogen was synthesized by PHAs degradation in the aerobic stage. Microbial community structure indicated that Candidatus Contendobacter was the most prevalent GAOs. We found that the ethylmalonyl-CoA (EMC) pathway was the crucial pathway supplying the core substance propionyl-CoA for poly-β-hydroxyvalerate (PHV) synthesis in Candidatus Contendobacter. All genes in EMC pathway were mainly located in Candidatus Contendobacter by gene source analysis. The key genes expression of EMC pathway increased with Candidatus Contendobacter enrichment, further validating that propionyl-CoA was synthesized by Candidatus Contendobacter predominantly via EMC pathway. Our work revealed the novel mechanisms underlying PHV synthesis through EMC pathway and further improved the intercellular storage metabolism of GAOs.
在此，在序批式反应器中通过厌氧-好氧模式运行了一个稳定的糖原积累微生物（GAOs）系统。我们重点研究了GAOs中聚羟基脂肪酸酯（PHA）储存的代谢机制。我们的系统显示出糖原积累代谢（GAM）的典型特征。在厌氧阶段，糖原消耗之后是乙酸摄取以合成聚-β-羟基链烷酸酯（PHA），并且在好氧阶段通过PHA降解合成糖原。微生物群落结构表明，“候选竞争杆菌属（Candidatus Contendobacter）”是最普遍的GAOs。我们发现，乙基丙二酰辅酶A（EMC）途径是为“候选竞争杆菌属”中聚-β-羟基戊酸酯（PHV）合成提供核心物质丙酰辅酶A的关键途径。通过基因来源分析，EMC途径中的所有基因主要位于“候选竞争杆菌属”中。随着“候选竞争杆菌属”的富集，EMC途径的关键基因表达增加，进一步证实了丙酰辅酶A主要由“候选竞争杆菌属”通过EMC途径合成。我们的工作揭示了通过EMC途径合成PHV的新机制，并进一步改善了GAOs的细胞内储存代谢。
