Human gut bacteria, such as member of the Bacteroides, often encode numerous parallel pathways for nutrient utilization. As a consequence, the genes encoding these responses are regulated at the local level and the global level. While the mechanisms of local gene regulation, often through the action of transcriptional regulators (hybrid two component systems, extra-cytoplasmic function sigma and anti-sigma factors, plus others) are better understood, the mechanisms of global regulation are still being unraveled. Several studies to date indicate that model species like B. thetaiotaomicron and B. ovatus possess “hierarchical” polysaccharide utilization behaviors in which more preferred nutrients are consumed first while less preferred nutrients are reserved for later growth after those with higher priority are depleted or gone. This behavior is similar to carbon catabolite repression in bacteria like E. coli but appears to occur through different mechanisms. These mechanisms, as well as the implications of this behavior in vivo in the gut, are being investigated in several projects.
Read more on this topic:
1. Tuncil YE, Xiao Y, Porter NT, Reuhs BL, Martens EC, Hamaker BR. 2017. Reciprocal Prioritization to Dietary Glycans by Gut Bacteria in a Competitive Environment Promotes Stable Coexistence. MBio 8: pii: e01068-1
2. Pudlo NA, Urs K, Kumar SS, German JB, Mills DA, Martens EC. 2015. Symbiotic Human Gut Bacteria with Variable Metabolic Priorities for Host Mucosal Glycans. MBio 6:e01282-15
3. Rogers TE, Pudlo NA, Koropatkin NM, Bell JS, Moya Balasch M, Jasker K, Martens EC. 2013. Dynamic responses of Bacteroides thetaiotaomicron during growth on glycan mixtures. Molecular Microbiology 88:876-90
4. Martens EC, Roth R, Heuser JE, Gordon JI. 2009. Coordinate regulation of glycan degradation and polysaccharide capsule biosynthesis by a prominent human gut symbiont. Journal of Biological Chemistry 284:18445-57