INFLUENCE OF STRESS CONDITIONS ON BACTEROIDES-FRAGILIS SURVIVAL AND PROTEIN PROFILES

Bacteroides fragilis strains isolated from different sources, i.e. 1 s train (AA1) from an aquatic environment, 1 strain from normal flora (1 18310) and the type strain (ATCC 25285) originally isolated from clini cal material, were analysed for both cell envelope proteins compositio n and surviving under oxidative stress starvation. All strains examine d showed a similar survival response when cultured in drinking water w ith a ten-fold decrease in viable counts per day during the 7 days of analysis. The outer membrane protein (OMP) profiles of all strains wer e quite similar during the stress period as determined by sodium dodec yl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). However, the periplasmic proteins of the strain 118310 showed two protein bands at 48 and 58 kDa, respectively, that were absent in the strains AA1 and ATCC 25285 during the incubation period in potable water. Whole cells and periplasmic S-35-labelled proteins from bacteria cultured in drink ing water showed a significant increase in proteins at 16, 18, 24, 26, 35, 48, and 58 kDa and 18, 22, 24, 48, 58, and 70 kDa, respectively, in all strains when compared to cells grown in BHI-PRAS media as detec ted by autoradiography following SDS-PAGE. These data suggest that B. fragilis may have a synthesis mechanism that allows them to adapt to a dverse environments.