The human gut can be viewed as a flow-through system with a short residence time, a high turnover rate and a spatial gradient of physiological conditions. As a consequence, the gut microbiota is exposed to highly fluctuating environmental determinants presented by the host and diet. Here, we assessed the fermentation and colonisation of insoluble wheat bran by faecal microbiota of three individuals at an unprecedented sampling intensity. Time-resolved 16S rRNA gene amplicon sequencing, revealed a dynamic microbial community, characterised by abrupt shifts in composition, delimiting states with a more constant community, giving rise to a succession of bacterial taxa alternately dominating the community over a 72 h timespan. Early stages were dominated by Enterobacteriaceae and Fusobacterium species, growing on the carbohydrate-low, protein rich medium to which wheat bran was supplemented. The onset of wheat bran fermentation, marked by a spike in short chain fatty acid production with an increasing butyrate proportion and an increased endo-1,4-β-xylanase activity, corresponded to donor-dependent proportional increases of Bacteroides ovatus/stercoris, Prevotella copri and Firmicutes species, which were strongly enriched in the bran-attached community. Literature and database searches provided novel insights into the metabolic and growth characteristics underlying the observed succession and colonisation, illustrating the potency of a time-resolved analysis to increase our understanding of gut microbiota dynamics upon dietary modulations.

中文翻译：

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由于生态位多样化，麦麸发酵过程中的微生物演替和人类粪便微生物群的定殖。

人体肠道可以看作是一个滞留时间短、周转率高、生理条件空间梯度大的流通系统。因此，肠道微生物群暴露于宿主和饮食带来的高度波动的环境决定因素。在这里，我们以前所未有的采样强度评估了三个个体的粪便微生物群对不溶性麦麸的发酵和定植。时间分辨 16S rRNA 基因扩增子测序揭示了一个动态的微生物群落，其特征是组成突然变化，用更恒定的群落界定状态，产生一系列细菌类群在 72 小时的时间内交替主导群落。早期阶段以肠杆菌科和梭杆菌属为主，生长在低碳水化合物、富含蛋白质并补充有麦麸的培养基上。麦麸发酵的开始，以短链脂肪酸产量激增为标志，丁酸比例增加，内切 1,4-β-木聚糖酶活性增加，对应于卵形拟杆菌/粪类杆菌、普雷沃菌的供体依赖性比例增加菌门和厚壁菌门物种，在麸皮附着的群落中大量富集。文献和数据库搜索为观察到的演替和定植背后的代谢和生长特征提供了新的见解，说明了时间分辨分析的效力，以增加我们对饮食调节时肠道微生物群动态的理解。