Ethylmalonyl-CoA pathway involved in polyhydroxyvalerate synthesis in Candidatus Contendobacter

• Published in: AMB Express 2022-03, Vol.12 (1), p.39-39, Article 39
• Main Authors: Zhao, Chen, Zhang, Chunchun, Shen, Zhiqiang, Yang, Yanping, Qiu, Zhigang, Li, Chenyu, Xue, Bin, Zhang, Xi, Yang, Xiaobo, Wang, Shang, Wang, Jingfeng
• Format: Article
• Language: English
• Subjects: Acetic acid; Bioaccumulation; Biomedical and Life Sciences; Biotechnology; Candidatus Contendobacter; Community structure; EMC pathway; Gene expression; Genes; Glycogen; Glycogen-accumulating organism; Glycogens; Life Sciences; Metabolism; Microbial Genetics and Genomics; Microbiology; Microorganisms; Original; Original Article; PHV; Propionyl-CoA; Sequencing batch reactor; Synthesis
• ISSN: 2191-0855; 2191-0855
• 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. Key points We observed GAM characteristic in the GAOs enrichment system. Metagenome-based analysis revealed that Candidatus Contendobacter was the dominant GAOs. The EMC pathway was a novel propionyl-CoA synthesis pathway for PHV in Candidatus Contendobacter .