Martens Eric C, Chiang Herbert C, Gordon Jeffrey I
Center for Genome Sciences, Washington University School of Medicine, St. Louis, MO 63108, USA.
Cell Host Microbe. 2008 Nov 13;4(5):447-57. doi: 10.1016/j.chom.2008.09.007.
The distal human gut is a microbial bioreactor that digests complex carbohydrates. The strategies evolved by gut microbes to sense and process diverse glycans have important implications for the assembly and operation of this ecosystem. The human gut-derived bacterium Bacteroides thetaiotaomicron forages on both host and dietary glycans. Its ability to target these substrates resides in 88 polysaccharide utilization loci (PULs), encompassing 18% of its genome. Whole genome transcriptional profiling and genetic tests were used to define the mechanisms underlying host glycan foraging in vivo and in vitro. PULs that target all major classes of host glycans were identified. However, mucin O-glycans are the principal host substrate foraged in vivo. Simultaneous deletion of five genes encoding ECF-sigma transcription factors, which activate mucin O-glycan utilization, produces defects in bacterial persistence in the gut and in mother-to-offspring transmission. Thus, PUL-mediated glycan catabolism is an important component in gut colonization and may impact microbiota ecology.
人类远端肠道是一个消化复杂碳水化合物的微生物生物反应器。肠道微生物进化出的感知和处理各种聚糖的策略，对这个生态系统的组装和运作具有重要意义。源自人类肠道的细菌多形拟杆菌以宿主聚糖和膳食聚糖为食。它靶向这些底物的能力存在于88个多糖利用位点（PULs）中，占其基因组的18%。利用全基因组转录谱分析和基因测试来确定体内和体外宿主聚糖觅食的潜在机制。鉴定出了靶向所有主要类型宿主聚糖的PULs。然而，粘蛋白O-聚糖是体内觅食的主要宿主底物。同时缺失五个编码ECF-σ转录因子的基因，这些因子可激活粘蛋白O-聚糖的利用，会导致细菌在肠道内的持久性以及母婴传播出现缺陷。因此，PUL介导的聚糖分解代谢是肠道定植的一个重要组成部分，可能会影响微生物群生态。
