Chitinase activity of Xenorhabdus and Photorhabdus species, bacterial associates of entomopathogenic nematodes.

Xenorhabdus nematophilus (three strains), Xenorhabdus bovienii (one strain), and Photorhabdus luminescens (one strain) showed both exo- and endochitinase activity using p-nitrophenyl-N-acetyl-beta-D-glucosaminide and p-nitrophenyl-beta-D-N,N',N'-triacetylchitotriose, respectively, as substrates. One to three bands were detected on PAGE gel with glycol chitin after electrophoresis. Variation in exo- and endochitinase activity among different species and strains was detected with the strongest activity in X. nematophilus and the weakest in P. luminescens. The primary form of X. bovienii had significantly greater chitinase activity than the secondary form, whereas their growth rate and total protein released into culture medium were similar. The partially purified chitinase of X. bovienii showed significant antimycotic activity against conidial germination and germ tube elongation of Botrytis cinerea.