FIG 2.

Corrin ring biosynthesis gene cluster from isolate A. muciniphila CSUN-17 (phylogroup AmII). (A) Presence of genes in the corrin ring biosynthesis gene cluster in phylogroups AmI, AmII, AmIII, and AmIV. Plus signs above the table indicate the presence of a gene in A. muciniphila CSUN phylogroup AmII isolates, determined using a PCR screen of A. muciniphila CSUN isolates. (B) Proposed strategy of propionate production in A. muciniphila CSUN-17 (phylogroup AmII), involving de novo vitamin B₁₂ biosynthesis and leading to activation of methylmalonyl-CoA synthase and conversion of succinate to propionate.