Effects of Flavobacterium lutescens Growth on Populations of Escherichia coli and Streptococcus faecalis in Water Following Thermal Loading

Flavobacterium lutescens has been observed to constitute a major segment of the aerobic, heterotrophic bacterial populations in nonpolluted aquatic systems. It is present in lesser numbers in the presence of municipal sewage and higher concentrations of organic wastes. In laboratory tests, in water from nonpolluted systems, this species became the predominant bacterial type following thermal addition. When temperature was increased in water from polluted sources, F. lutescens became a major component of the bacterial populations. In the laboratory, the numbers of Escherichia coli and Streptococcus faecalis were observed to decrease in proportion to the increase in F. lutescens after thermal addition. Similar results were observed when water from three aquatic systems of differing nutrient content was tested. A greater amount of organic material present in the water reduced the predominance of F. lutescens. These results indicate that, without use of chemical additives, this method may be useful for restoration of natural aquatic bacterial populations and reduction of undesirable microbial populations in water supplies.