Effects of medium composition on cell pigmentation, cytochrome content, and ferric iron reduction in a Pseudomonas sp. isolated from crude oil.

Cells of a pseudomonad associated with pipeline corrosion grown on a complex medium were orange in color and vigorously reduced ferric iron. The intensity of orange color of cells grown on a synthetic medium and their ability to reduce ferric iron was directly related to the iron content of the medium. Absorption spectrophotometric data show a direct relationship between color of cells, cytochrome content, and ability to reduce ferric iron. Carbon monoxide markedly, but not completely, inhibits the reduction of ferric iron. The data presented indicate that ferric iron can serve as a terminal electron acceptor for cytochrome-associated respiratory processes of this corrosive pseudomonad.