Fig. 6. Vitamin B12 supplementation repressed the expression of cob/cbi operons in the vitamin B12 biosynthesis pathway and promoted porphyrin production in P. acnes cultures.

(A) The expression levels of cbiL, cysG+cbiX, and btuR were significantly repressed on day 2, day 8, and day 14 after vitamin B12 supplementation in P. acnes cultures. The experiments were repeated three times independently. Each dot represents the average gene expression level of two to three technical replicates in each independent experiment. The dotted lines indicate the changes between the P. acnes cultures in medium only (black) and the cultures in medium with vitamin B12 supplementation (red). The mean of the gene expression levels from the three independent experiments is shown as a black bar. Significance was determined by Student’s t-test. The gene expression data are listed in table S7.

(B) Porphyrin production in P. acnes cultures on day 8 and day 14 after vitamin B12 supplementation was significantly increased. Significance was determined by Student’s t-test. Data are presented as the mean ± standard deviation. The experiments were repeated three times independently with three to four biological replicates each time. The porphyrin levels are listed in table S8.