THE GLYCEROL DEHYDROGENASES OF PSEUDOMONAS SALINARIA, VIBRIO COSTICOLUS, AND ESCHERICHIA COLI IN RELATION TO BACTERIAL HALOPHILISM

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Abstract
Glycerol dehydrogenases from the extremely halophilic P. salinaria and the moderately halophilic V. costicolus are descr. and compared with the corresponding enzyme from the nonhalophilic E. coli. The properties of all 3 enzymes are similar except their responses to salt concn. The enzymes from E. coli and V. costicolus are most active at NaCl concns. of about 0.25 [image] and 0.5 [image] respectively; that from P. salinaria is most active in the presence of 1.5 [image] NaCl and is irreversibly inactivated in the absence of salt. All 3 enzymes are more active in the presence of KC1 than of NaCl at any molar concn. These results suggest that the extremely halophilic bacteria contain high concns. of salt and that their enzymes function maximally at these high concns. In contrast, the moderately halophilic organisms contain relatively little salt and their enzymes are more comparable with those of nonhalophiles.