Effect of Chitinase-Producing Paenibacillus illinoisensis KJA-424 on Egg Hatching of Root-Knot Nematode (Meloidogyne incognita)

Abstract

A bacterium having strong chitinolytic activity on 0.2% colloidal chitin-containing agar medium was isolated from coastal soil in Korea. Based on the nucleotide sequence of a conserved segment of a 16S rRNA gene, the bacterium was identified as Paenibacillus illinoisensis KJA-424. The population of P. illinoisensis KJA-424 and chitinase activity significantly increased for the first 2 days of incubation. On SDS-PAGE analysis with 0.01% glycol chitin, three protein bands (63, 54, and 38 kDa) with chitinolytic activity were detected. The effect of P. illinoisensis KJA-424 on the egg hatch of root-knot nematode (Meloidogyne incognita) was investigated. After 7 days of incubation with the chitinase- producing P. illinoisensis KJA-424, none of the eggs hatched, whereas a 39.8% egg hatching rate was observed in the water control. Inverted and scanning electron microscopic observations demonstrated that P. illinoisensis KJA-424 deformed and destroyed the eggshell of M. incognita. In conclusion, chitinase produced by P. illinoisensis KJA-424 caused the lysis of M. incognita eggshell and resulted in the inhibition of egg hatching in vitro.