Interactions between Escherichia coli and the plant-parasitic nematode Meloidogyne java']javanica

To determine the potential of the plant-parasitic nematode Meloidogyne javanica to serve as a temporary reservoir for Escherichia coli. The adhesion to and persistence of E. coli on the surface of M. javanica were evaluated at different times and temperatures. A pure culture of green fluorescent protein (GFP) tagged E. coli was mixed with ca. 1000 J2 M. javanica for 2 h at 25 degrees C. The nematodes were then washed and the rate of the adhesion of the bacteria to the nematodes was determined by counting the viable nematode-associated E. coli, and by fluorescence microscopy. A dose-dependent adhesion rate was observed only at a bacterium to nematode ratio of 10(4)-10(6) : 1. The adhesion of E. coli to the nematodes was also tested over a 24 h-period at 4 degrees C, 25 degrees C and 37 degrees C. At 4 degrees C and 37 degrees C, maximal adhesion was observed at 5 h; whereas at 25 degrees C, maximal adherence was observed at 8 h. Survival experiments showed that the bacteria could be detected on the nematodes for up to 2 weeks when incubated at 4 degrees C and 25 degrees C, but not at 37 degrees C. Under laboratory conditions, at 4 degrees C and 25 degrees C, M. javanica could serve as a temporary vector for E. coli for up to 2 weeks. These findings support the hypothesis that, in the presence of high concentrations of E. coli, M. javanica might serve as a potential vehicle for the transmission of food-borne pathogens.