Influence of Lysobacter enzymogenes Strain C3 on Nematodes.pdf

Influence of Lysobacter enzymogenes Strain C3 on Nematodes J. Chen,1 W. H. Moore,1 G. Y. Yuen,2 D. Kobayashi,3 E. P. Caswell-Chen1 Abstract: Chitinolytic microflora may contribute to biological control of plant-parasitic nematodes by causing decreased egg viability through degradation of egg shells. Here, the influence of Lysobacter enzymogenes strain C3 on Caenorhabditis elegans, Heterodera schachtii, Meloidogyne javanica, Pratylenchus penetrans, and Aphelenchoides fragariae is described. Exposure of C. elegans to L. enzymogenes strain C3 on agar resulted in almost complete elimination of egg production and death of 94% of hatched juveniles after 2 d. Hatch of H. schachtii eggs was about 50% on a lawn of L. enzymogenes strain C3 on agar as compared to 80% on a lawn of E. coli. Juveniles that hatched on a lawn of L. enzymogenes strain C3 on agar died due to disintegration of the cuticle and body contents. Meloidogyne javanica juveniles died after 4 d exposure to a 7-d-old chitin broth culture of L. enzymogenes strain C3. Immersion of A. fragariae, M. javanica, and P. penetrans juveniles and adults in a nutrient broth culture of L. enzymogenes strain C3 led to rapid death and disintegration of the nematodes. Upon exposure to L. enzymogenes strain C3 cultures in nutrient broth, H. schachtii juveniles were rapidly immobilized and then lysed after three days. The death and disintegration of the tested nematodes suggests that toxins and enzymes produced by this strain are active against a range of nematode species. Key words: Aphelenchoides fragariae, biological control, Caenorhabditis elegans, chitinase-producing bacterium, Heterodera schachtii, Lysobacter enzymogenes, lytic, Meloidogyne javanica, Pratylenchus penetrans, nematode management, plant-parasitic nematodes The egg shell of nematodes contains chitin (Maggenti, 1981; Bird and Bird, 1991), and it is pre- sumed that exposing eggs to chitinase can disrupt egg hatch. Both chitinase and chitinase-producing bacteria