Proteases from Bacillus: a new insight into the mechanism of action for rhizobacterial suppression of nematode populations

Abstract

Aims: The aim of this study was to investigate the role of proteases in Bacillus spp. of rhizobacteria in suppressing nematode populations and to understand their mechanism of action. Methods and Results: Rhizobacteria with nematicidal activity were isolated from soil samples of five root knot nematode‐infested farms. Among these strains, nematotoxicities of Bacillus strains were intensively analysed. Further assays of nematicidal toxins from Bacillus sp. strain RH219 indicated an extracellular cuticle‐degrading protease Apr219 was an important pathogenic factor. The Apr219 shared high similarity with previously reported cuticle‐degrading proteases from Brevibacillus laterosporus strain G4 and Bacillus sp. B16 (Bacillus nematocida). The cuticle‐degrading protease genes were also amplified from four other nematicidal Bacillus strains isolated from the rhizosphere. In addition to Apr219, a neutral protease Npr219 from Bacillus sp. RH219 was also investigated for activity against nematodes. Conclusions: The wide distribution of cuticle‐degrading proteases in Bacillus strains with nematicidal activity suggested that these enzymes likely play an important role in bacteria–nematode–plant–environment interactions and that they may serve as important nematicidal factors in balancing nematode populations in the soil. Significance and Impact of the Study: Increased understanding of the mechanism of action of Bacillus spp. against nematodes could potentially enhance the value of these species as effective nematicidal agents and develop new biological control strategies.

Candidate nematicidal proteins in a new <i>Pseudomonas veronii</i> isolate identified by its antagonistic properties against <i>Xiphinema index</i>

“…The described characterization and identification of this new P. veronii isolate, and the functional assignments of these candidate proteins have been reinforced. The cuticle of nematodes is rigid and is composed of proteins and lipids that can be affected by hydrolytic enzymes from nematicidal bacteria (Lian et al, 2007). Our results suggested that at least these hydrolytic enzymes might be involved in the nematicidal activity via cuticle degradation of connective tissues in their digestive tracts (Yang et al, 2013).…”

An evaluation in vitro and in vivo of rhizobacteria in the biocontrol of Radopholus similis in banana

“…Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Lian et al, 2007). Recent surveys report that the bacteria Pseudomonas synxantha, Pseudomonas fluorescens, Bacillus subtilis, and Stenotrophomonas maltophilia showed toxic effect on eggs and juveniles under laboratory conditions indicating the occurrence of the production of antimicrobial metabolites (Ludwig et al, 2013).…”

Bacillus spp. isolates for the control of Meloidogyne incognita in common bean

“…The formation of resistant spores is a desirable feature for a biocontrol agent, since it provides greater field survival and longer shelf life to products formulated therefrom. In addition, Bacillus-based products are more environmentally safe than chemicals, and are compatible with conventional farming practices (Chen & Dickinson, 2004 (Kavitha et al, 2007;Lian et al, 2007;Tian et al, 2007;Mohammed et al, 2008;Araújo & Marchesi, 2009;Ann, 2013). The mechanisms of action of these bacteria against nematodes involve the production of nematotoxic substances, modification of root exudates of host plants, systemic resistance induction, and production of lethal proteases within the gut following the ingestion of the bacteria by the nematode (Araújo et al, 2002;Kavitha et al, 2007;Lian et al, 2007;Tian et al, 2007;Mohammed et al, 2008;Niu et al, 2010;Ann, 2013).…”