Screening of Rhizospheric Bacillus Isolates for Chitinase and Protease Production and Their Biocontrol Potential Against Meloidogyne spp

Abstract

Root-knot nematodes (Meloidogyne spp.) are among the most destructive soil-borne pests affecting a wide range of agricultural crops, causing severe root galling, impaired nutrient uptake, stunted growth, and significant yield losses. Biological control using rhizospheric bacteria has emerged as a sustainable alternative to chemical nematicides for nematode management. The present study was conducted to screen rhizospheric Bacillus isolates for chitinase and protease enzyme production and to evaluate their biocontrol potential against Meloidogyne spp. Rhizospheric soil samples were collected from healthy crop fields, and bacterial isolates were obtained using standard microbiological techniques. The isolates were characterized morphologically and biochemically, followed by qualitative and quantitative assays for chitinase and protease enzyme activity. Selected isolates exhibiting high enzymatic activity were further evaluated in laboratory and greenhouse experiments for their antagonistic effects against root-knot nematodes. Parameters including egg hatch inhibition, juvenile mortality, root gall reduction, and plant growth promotion were assessed to determine biocontrol efficiency. The results demonstrated considerable variability among Bacillus isolates in enzyme production and nematicidal activity. Several isolates showed strong chitinase and protease activity, which significantly inhibited egg hatching and increased juvenile mortality of Meloidogyne spp. In greenhouse trials, treated plants exhibited reduced root galling and improved growth parameters compared with untreated controls. The findings suggest that extracellular hydrolytic enzymes produced by rhizospheric Bacillus isolates play an important role in degrading nematode egg shells and suppressing nematode development. The study highlights the potential of indigenous Bacillus strains as eco-friendly biocontrol agents for integrated nematode management. Utilization of these beneficial rhizobacteria may contribute to sustainable crop protection, improved soil health, and reduced dependence on synthetic nematicides in agricultural production systems.