Physiological acclimatization in a medium amended with colloidal chitin improves the nematophagous capacity of a fungus on the tomato root-knot nematode

Purpureocillium lilacinum is a nematophagous fungus whose ability to control the plant parasitic nematode Nacobbus aberrans sensu lato has been demonstrated. In this study, physiological acclimatization was performed using different nutrient sources and water activity levels of the culture medium to improve the nematophagous activity of two strains of P. lilacinum (SR14 and SR38). The development of the fungal inoculum in a medium amended with colloidal chitin and reduced levels of water activity (0.95) stimulates the production of conidia and pathogenicity in vitro. This condition was selected to produce the fungal inoculum for conducting antagonism studies against N. aberrans s.l. in tomato plants. The nematode population was significantly reduced (94–96%) with the application of SR38 and SR14 + SR38. The physiological acclimatization in medium with colloidal chitin and 0.95 water activity stimulates the pathogenicity mechanisms (sporulation and infectivity) of P. lilacinum SR38, improving its nematophagous capacity.