RESPONSES OF DIVERSE HETEROTROPHIC BACTERIA TO ELEVATED COPPER CONCENTRATIONS

The influence of copper on the growth of Escherichia coil, Pseudomonas aeruginosa, Bacillus cereus, Bacillus subtilis, Vibrio parahaemolytic us, Vibrio alginolyticus (three strains), and an unidentified Vibrio s p. was examined in batch cultures. The effects of copper at micromolar concentrations varied from undetectable to complete growth inhibition . Each strain was able to recover from a growth lag observed after cop per addition at a characteristic concentration. Copper concentrations that allowed recovery ranged from 25 to 150 mu M Extracellular protein s in the medium of cultures that had recovered from copper stress were compared with those from control cultures. Protein profiles were anal yzed for the presence of proteins similar to extracellular copper-bind ing proteins (CuBP) previously reported in V. alginolyticus. CuBP-like proteins were found in each Vibrio sp. examined. A protein of similar molecular mass was also detected in copper-stressed cultures of P. ae ruginosa and not in control cultures. Escherichia coli and Bacillus sp p. did not produce CuBP-like proteins. The data show that CuBP-like pr oteins are not produced by all bacteria in response to copper stress a nd indicate that such proteins are common in marine Vibrio spp.