We investigated the requirement of 15 human butyrate-producing gut bacterial strains for eight B vitamins and the proteinogenic amino acids by a combination of genome sequence analysis and in vitro growth experiments. The Ruminococcaceae species Faecalibacterium prausnitzii and Subdoligranulum variabile were auxotrophic for most of the vitamins and the amino acid tryptophan. Within the Lachnospiraceae, most species were prototrophic for all amino acids and several vitamins, but biotin auxotrophy was widespread. In addition, most of the strains belonging to Eubacterium rectale and Roseburia spp., but few of the other Lachnospiraceae strains, were auxotrophic for thiamine and folate. Synthetic coculture experiments of five thiamine or folate auxotrophic strains with different prototrophic bacteria in the absence and presence of different vitamin concentrations were carried out. This demonstrated that cross-feeding between bacteria does take place and revealed differences in cross-feeding efficiency between prototrophic strains. Vitamin-independent growth stimulation in coculture compared to monococulture was also observed, in particular for F. prausnitzii A2-165, suggesting that it benefits from the provision of other growth factors from community members. The presence of multiple vitamin auxotrophies in the most abundant butyrate-producing Firmicutes species found in the healthy human colon indicates that these bacteria depend upon vitamins supplied from the diet or via cross-feeding from other members of the microbial community.

中文翻译：

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人类肠道丁酸生产细菌的维生素生物合成和合成微生物群落的交叉喂养。


我们通过基因组序列分析和体外生长实验相结合，研究了 15 种人类产丁酸肠道细菌菌株对 8 种 B 族维生素和蛋白氨基酸的需求。瘤胃球菌科物种普氏粪杆菌（Faecalibacter prausnitzii）和变异细粒菌（Subdolimillion variabile）对于大多数维生素和氨基酸色氨酸是营养缺陷型的。在毛螺菌科中，大多数物种对所有氨基酸和几种维生素都是原养型，但生物素营养缺陷型很普遍。此外，大多数属于直肠真杆菌和罗斯伯利亚属的菌株，但其他毛螺菌科菌株中的少数菌株，对硫胺素和叶酸是营养缺陷型的。在不存在和存在不同维生素浓度的情况下，对五种硫胺素或叶酸营养缺陷型菌株与不同的原养细菌进行了合成共培养实验。这证明细菌之间确实发生了交叉喂养，并揭示了原养菌株之间交叉喂养效率的差异。与单一共培养相比，共培养中也观察到了不依赖于维生素的生长刺激，特别是对于F. prausnitzii A2-165，这表明它受益于群落成员提供的其他生长因子。在健康人类结肠中发现的最丰富的产生丁酸盐的厚壁菌属物种中存在多种维生素营养缺陷型，这表明这些细菌依赖于饮食中或通过微生物群落其他成员的交叉喂养提供的维生素。