Brevibacillus laterosporus as a Natural Biological Control Agent of Soil-Dwelling Nematodes

Abstract

The nematocidal potential of an entomopathogenic strain of Brevibacillus laterosporus previously known for its antimicrobial properties was assessed on the free-living nematode microworm Panagrellus redivivus and the root-knot nematode Meloidogyne incognita. Laboratory bioassays showed significant nematocidal properties of the culture supernatant of the bacterium, achieving over 90% mortality of both microworms and M. incognita juveniles when the supernatant was collected at the sporulation phase, which related to the progressive production and release of virulence factors and toxins in the culture medium at this stage of bacterial growth. A protein fraction obtained by precipitation from the bacterial culture supernatant was found to be very active against nematodes with a concentration-dependent effect and an LC50 value of 0.4 µg/µL on M. incognita. Bacterial preparations based on either spores or a culture supernatant proved to be effective in reducing M. incognita density in treated compared with untreated soil, which makes the use of B. laterosporus as a biological control agent of soil-dwelling nematode pests particularly promising.