A small, gram-negative coccobacillus was isolated from molluscicide test chambers which had contained Australorbis glabratus (PR strain). Of eight molluscicides tested, the following (in saturated solution) could serve as sole source of nitrogen for the bacterium in the presence of glucose as a source of carbon and energy: Bayluscide, ICI 24223, WL 8008, Zirame, and Dinex. 2 tert. butyl 4–6 dinitrophenol could also serve as a nitrogen source at half-saturation. Sodium PCP and 2–4 dinitro-6-phenylphenol were antimicrobial in action.
The effect of bacterial degradation upon toxicity was tested, and it was shown that the molluscicidal action of Bayluscide, ICI 24223, and WL 8008 was significantly reduced by bacterial action. No significant effect was observed on the other chemicals tested. It was further shown that concentrated solutions of Bayluscide and ICI 24223 inoculated with bacterial isolates began to lose activity within 48 hours. The importance of these observations is discussed, with primary reference to molluscicide application under conditions of stagnant, organic rich waters, and as residual agents.