Abstract
An ultrasonication method was developed to study the effect of nematodes on the chlorination of bacteria and to investigate numbers of bacteria associated with nematodes isolated from a distribution system. The organisms selected for this study were Nematoda Rhabditis sp. and Bacteria Escherichia coli C600. Thé results of experiment showed that ultrasonication of nematodes was effective for determining the numbers of bacteria in the body of the nematode and the most suitable condition of ultrasonication was 40 w for 60 sec. It was clear that resistance of associated bacteria to free chlorine was 1, 000 times higher than that of unassociated bacteria and there was a positive correlation between the survive ratio of associated bacteria and nematodes, which suggested that surviving nematodes can serve as carriers to protect bacteria lived in their body from chlorination and decreasing the survive ratio of nematodes will be effective for decreasing that of bacteria. The results of investigation on numbers of bacteria associated with nematodes isolated from an actual distribution system showed that a lot of viable bacteria were detected from surviving nematodes treated by ultrasonication, which confirmed the above experiment results and suggested that viable bacteria associated with nematodes might leak into the distribution system.
