The effect of water movement on lysis of non-marine microorganisms by marine bacteria

Abstract

It has been demonstrated that the kill of non-marine microorganisms in the sea is directly related to the size of the marine microbial population. In the deep sea where the microorganisms are sparse there is a minimal effect on non-marine microorganisms. However, water sampled from coastal zones had a strong killing effect. Large numbers of non-marine microorganisms are carried into the sea in sewage and in surface drainage waters. These microorganisms, which are foreign to the marine environment, rapidly disappear in the sea. Hypotheses proposed to account for this decline include dilution by ocean currents (Vaccaro et al. 1950), physico-chemical factors (Pramer et al. 1963), and toxic products of marine microorganisms (Jones 1963). We have been concerned in our laboratory with the contribution of the indigenous marine microflora on the killing of intestinal bacteria carried into the sea in sewage, represented by Escherichia coli, and of soil fungi, represented by Pythium debaryanum. In an earlier study we isolated bacteria capable of enzymatically degrading E. coli from the sea (MITCHELL & NEVO 1965). These marine bacteria killed E. coli when added to artificial sea water. In the current study we have investigated the contribution of the indigenous marine microflora in polluted areas and in the open sea to the killing of non-marine microorganisms.