Purification and properties of a Meloidogyne-antagonistic chitinase from Lysobacter capsici YS1215

The root-knot nematodes, Meloidogyne spp., cause serious diseases in various plants and their chemical control may lead to environmental problems. Therefore, alternative control measures against the phytopathogenic nematodes are being sought. One of the potential targets against Meloidogyne spp. may be the chitinolysis and degradation of nematode eggs. Therefore, in the present study, a chitinolytic and nematicidal strain of Lysobacter capsici YS1215 was isolated from an agricultural field in Korea. The aim of this study was to purify chitinase secreted by L. capsici YS1215 and investigate its nematicidal role against Meloidogyne incognita. The chitinase secreted by L. capsici YS1215 was purified by protein precipitation with 80% ammonium sulphate, anion-exchange chromatography with DEAE-cellulose and gel-filtration chromatography with Sephadex G-100. By chitinase-active staining of the purified enzyme, a single band was obtained with an estimated molecular mass of 43.6 kDa. The optimal pH and optimal temperature for the highest chitinase activity were 6.0 and 40 degrees C, respectively. The purified chitinase degraded the chitin layer of the eggshells and significantly reduced hatch of second-stage juveniles. The activity of chitinase secreted by L. capsici YS1215 was not affected by CoCl2, MnCl2, MgCl2, CuSO4, CaCl2 or EDTA. The purified enzyme could also hydrolyse swollen chitin, glycol chitin, glycol chitosan and chitin powder. Thus, the role of chitinase secreted by L. capsici YS1215 against Meloidogyne spp. may be useful for further development of a biocontrol agent.