Nature of the Bactericidal Agent in Sea Water

Abstract

EARLIER work by myself in co-operation with Miss R. E. Martin upon the toxicity of sea water towards Escherichia coli demonstrated the presence, in the coastal waters of New Zealand, of the bactericidal agent which has been observed by other workers and been the subject of a recent review by Greenberg¹. We also found that this organism will survive and actively multiply in sea water containing a very small addition of lactose broth. Assuming that some constituent of the lactose broth was able to antagonize the toxic effect of the sea water, well-washed cultures of E. coli were suspended in mixtures of sea water and the individual constituents of lactose broth. The meat extract (‘Lab lemco’) was found to contain the protective agent. Yeast extract behaved similarly.