Data_Sheet_2_Bacterial Microcompartment-Dependent 1,2-Propanediol Utilization of Propionibacterium freudenreichii.XLSX

Bacterial microcompartments (BMCs) are proteinaceous prokaryotic organelles that enable the utilization of substrates such as 1,2-propanediol and ethanolamine. BMCs are mostly linked to the survival of particular pathogenic bacteria by providing a growth advantage through utilization of 1,2-propanediol and ethanolamine which are abundantly present in the human gut. Although a 1,2-propanediol utilization cluster was found in the probiotic bacterium Propionibacterium freudenreichii, BMC-mediated metabolism of 1,2-propanediol has not been demonstrated experimentally in P. freudenreichii. In this study we show that P. freudenreichii DSM 20271 metabolizes 1,2-propanediol in anaerobic conditions to propionate and 1-propanol. Furthermore, 1,2-propanediol induced the formation of BMCs, which were visualized by transmission electron microscopy and resembled BMCs found in other bacteria. Proteomic analysis of 1,2-propanediol grown cells compared to L-lactate grown cells showed significant upregulation of proteins involved in propanediol-utilization (pdu-cluster), DNA repair mechanisms and BMC shell proteins while proteins involved in oxidative phosphorylation were down-regulated. 1,2-Propanediol utilizing cells actively produced vitamin B12 (cobalamin) in similar amounts as cells growing on L-lactate. The ability to metabolize 1,2-propanediol may have implications for human gut colonization and modulation, and can potentially aid in delivering propionate and vitamin B12in situ.

细菌微区室（Bacterial microcompartments，BMCs）是一类由蛋白质构成的原核细胞器，可介导1,2-丙二醇、乙醇胺等底物的代谢利用。BMCs多与特定致病菌的存活密切相关：通过代谢利用人体肠道内丰度较高的1,2-丙二醇与乙醇胺，为致病菌提供生长优势。尽管在益生菌费氏丙酸杆菌（Propionibacterium freudenreichii）中已发现1,2-丙二醇利用基因簇，但目前尚未有实验证实该菌中存在BMC介导的1,2-丙二醇代谢途径。本研究证实，费氏丙酸杆菌DSM 20271可在厌氧条件下将1,2-丙二醇代谢为丙酸盐与1-丙醇。此外，1,2-丙二醇可诱导BMCs的形成：通过透射电子显微镜观察到的BMCs形态与其他细菌中的BMCs高度相似。对1,2-丙二醇培养细胞与L-乳酸盐培养细胞的蛋白质组学比较分析显示：1,2-丙二醇培养细胞中，参与1,2-丙二醇代谢的蛋白（pdu基因簇）、DNA修复相关蛋白以及BMC外壳蛋白均显著上调，而与氧化磷酸化相关的蛋白则显著下调。利用1,2-丙二醇的细胞可主动合成维生素B12（钴胺素，cobalamin），其合成量与L-乳酸盐培养的细胞相当。费氏丙酸杆菌的1,2-丙二醇代谢能力可能对人体肠道定殖与菌群调控具有潜在意义，还可在肠道原位递送丙酸盐与维生素B12。