Distinct polysaccharide utilization as determinants for interspecies competition between intestinal Prevotella spp.

Prevotella spp. form one of the most dominant bacterial genera in the human gut. Multiple Prevotella spp. can co-exist in some but not all individuals consuming plant-based diets. To functionally investigate the relationship between Prevotella competition and diet, we isolated several novel Prevotella spp. from the mouse gut, performed genome and metatranscriptome analysis as well as a series of competition experiments under different dietary conditions. These experiments revealed that diverse dominant Prevotella species compete for similar metabolic niches in vivo, which is linked to the upregulation of specific Polysaccharide Utilization Loci (PULs). Complex plant-derived polysaccharides are required, and particularly arabinoxylan is sufficient, for the expansion of Prevotella spp. The most dominant Prevotella species encodes a specific tandem-repeat trsusC/D PUL, which is conserved in highly abundant Prevotella copri strains further expanded in humans consuming a vegan diet. Our data suggest efficient (arabino)xylan-utilization as a factor contributing to Prevotella dominance.

普雷沃氏菌属（Prevotella spp.）是人体肠道内最为优势的细菌菌属之一。在部分食用植物性饮食的个体体内，可共存多种普雷沃氏菌属菌种，但并非所有食用该类饮食的个体均存在此现象。为从功能层面探究普雷沃氏菌的竞争关系与饮食之间的关联，我们从小鼠肠道中分离得到数株新型普雷沃氏菌属菌种，开展了基因组与宏转录组分析，以及一系列不同饮食条件下的竞争实验。实验结果显示，多样的优势普雷沃氏菌菌种在体内会竞争相似的代谢生态位，这一现象与特定多糖利用位点（Polysaccharide Utilization Loci, PULs）的上调表达密切相关。复杂的植物源性多糖是普雷沃氏菌属菌种增殖所必需的，其中阿拉伯木聚糖（arabinoxylan）即可单独满足其增殖需求。最为优势的普雷沃氏菌菌种编码一种特定的串联重复trsusC/D型多糖利用位点，该位点在食用纯素饮食的人群体内丰度显著升高的柯氏普雷沃氏菌（Prevotella copri）菌株中同样保守存在。我们的研究数据表明，高效利用（阿拉伯）木聚糖是推动普雷沃氏菌成为肠道优势菌种的关键因素之一。