RT Journal Article SR Electronic(1) A1 Tracy, OonaghYR 1969 T1 Pigment Production in Bacteroides JF Journal of Medical Microbiology, VO 2 IS 3 SP 309 OP 315 DO https://doi.org/10.1099/00222615-2-3-309 PB Microbiology Society, SN 1473-5644, AB SUMMARY Chromogenesis by three members of the genus Bacteroides was studied. The species investigated were: Bacteroides melaninogenicus, B. fragilis and B. necrophorus. All were capable of pigment production, but each species required a different set of factors for chromogenesis. All needed cysteine and ferrous sulphate. These factors sufficed for pigment production by B. melaninogenicus. Additional vitamin K1 was essential for pigment production by both B. necrophorus and B. fragilis, but the latter also required haemin. Pigment production by B. melaninogenicus was studied in two media: 5 per cent, horse blood agar, and an agar-free partially defined medium. The pigment was harvested from these media, purified and subjected to chemical analysis. This pigment, previously thought to be haemin, proved to be colloidal ferrous sulphide. The pigment produced by two other Bacteroides species, B. fragilis and B. necrophorus, examined in the same way also proved to be colloidal ferrous sulphide., UL https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-2-3-309