Cell envelope proteins of environmental Vibrio cholerae non O1 isolates from Albufera Lake (Valencia, Spain) influence of some factors on OMP expression

Abstract

The cell envelope proteins of 89 environmental Vibrio cholerae non O1 strains isolated from lake and coastal waters near Valencia, Spain, and six Vibrio cholerae strains from culture collections were analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Considerable heterogeneity was found in the major proteins of the environmental non-O1 strains, but bands between 25,000 and 48,000 daltons were observed in the majority of the strains. Estimated relative mobilities of the total protein profile ranged between 11 and more than 100 Kd. Cluster analysis revealed four groups of strains distinguishable by presence or absence of high and low molecular weight proteins. After treatment with Sarkosyl, the outer membrane proteins (OMPs) were characterized in all strains by densitometric methods. They ranged from 19 to 87 Kilodaltons, and corresponded to the major proteins observed in the total membrane preparations. The major OMP most frequently found had a molecular weight around 37 Kd, similar to that of porins in other Gram-negative bacteria. The OMP composition varied in response to culture medium and growth phase. Generally the OMP expression was affected only in a quantitative way by the growth phase while the growth medium had both a qualitative and a quantitative effect.