Detection of a Vibrio sp. by the Bacteriophagous Nematode Pelodera chitwoodi

S ummary . Pelodera chitwoodi was able to distinguish between a Vibrio sp. (food bacterium) and Chromobacterium janthinum (non-food bacterium), and between bacteria and mud. Nematodes migrated preferentially to the Vibrio sp. at various distances, temperatures, and pH values. Migration to food bacteria increased with an increase in bacterial concentration. Resting and dead bacteria failed to attract nematodes. Nematodes were able to detect a vibrio colony separated from them by a plastic barrier, and migrated to areas on agar containing exudate and dialysate from the vibrio. Both exudate and dialyzate contained 4 amino acids and 3 vitamins which attracted nematodes. However, attraction of nematodes to these compounds was not as strong as to metabolizing bacteria, indicating that additional compounds were also involved.