Membrane-bound respiratory system of Enterobacter cloacae strain HO1 grown anaerobically with chromate.

Chromate has been demonstrated to be an electron acceptor in the respiratory chain of anaerobically grown Enterobacter cloacae strain HO1. By using potentiometric titration and low temperature spectroscopy, the spectral absorption of the anaerobic membrane vesicles of this organism in the presence of chromate was resolved into six peaks at 548, 549, 550, 555, 556, and 558 nm in the alpha band of the reduced minus oxidized spectra. The spectra elicited by chromate are attributed to cytochromes c548, c549, c550, b555, b556, and b558. Among these cytochromes, c548 was found to be specifically involved in electron transfer to chromate.