STUDY OF THE GELATINOLYTIC ACTIVITIES OF ESCHERICHIA-COLI-CELLS BEFORE AND AFTER STARVATION IN SEAWATER BY SUBSTRATE GEL-ELECTROPHORESIS

Previous work has shown that clinical Escherichia coli strains, starve d in seawater, are able to present residual growth, with subsequent al terations to their enzymatic activities and metabolism. Gelatinolytic activity of starved cells is of importance because it appears and incr eases gradually with time. In this work, several forms of gelatinolyti c activity were detected by SDS-polyacrylamide gel electrophoresis, di ffering in molecular masses and appearance, before and after starvatio n of E. coli cells. The enzymic forms are classified into 4 categories according to the effect of certain inhibitors on the appearance of ge latinolytic activity: a. those whose appearance is inhibited by the ch elating factors EDTA, 1,10-phenanthroline and whose presence is also i nhibited by N-ethylmaleimide (metalloproteinases with thiol group acti ve); b. those affected by the presence of chelators, N-ethylmaleimide and Ca2+ (Ca2+-dependent metalloproteinases with thiol group active); c. those inhibited by chelators and activated in the presence of Ca2(Ca2+-dependent metalloproteinases) and d. those whose appearance is i ndependent of the presence of inhibitors used. The forms of gelatinoly tic activity of the fourth category coincide with enzyme forms that ca n also use casein as substrate in electrophoresis. These data suggest that there are considerable differences in the gelatinolytic pattern o f clinical strains of E. coil cells before and after starvation in sea water.