Anaerobe/aerobe environmental flux determines protein expression profiles of Bacteroides fragilis, a redox pathogen

The oxidation-reduction (redox) of the environment characterizes the Bacteroides fragilis pathogenic potential. Previously, using 3D confocal laser scanning microscopy, the bacteria prepared from cultures grown under oxidizing conditions (Eh7ca. + 100 mV) were able to penetrate into Hela cell monolayers. In contrast, when grown under reducing conditions (Eh7ca. – 60 mV), there were no bacteria evident within Hela cells. The influence of the anaerobe/aerobe environmental flux during the process of the anaerobe infection could be significant. In B. fragilis peritonitis, this may depend on the occurrence of aerobiosis as opposed to anaerobiosis. To this end, three clinical B. fragilis strains, two infectious and one non-infectious, were grown under oxidizing and reducing conditions; then, the outer membrane protein expressions derived from these strains were assessed, following sarcosyl extraction and SDS-PAGE. The differences between the protein profiles from these strains when cultured under oxidizing and reducing conditions were found to be statistically significant for the two infectious strains, but not for the non-infectious strain. OMP profiles under aerobic conditions compared to anaerobic conditions exhibited products with a range of apparent molecular weights suggestive of unique participation in the interaction with the host cell.