Nano-silica immobilized chitinase enhances stability and rhizosphere biocontrol against Fusarium and root-knot nematodes

Abstract

Plant diseases caused by soil-borne pathogens represent a major challenge to sustainable agricultural production. Chitinase enzymes are considered promising biocontrol agents because they can degrade chitin, a major structural component of fungal cell walls and nematode egg shells. In the present study, chitinase from Streptomyces griseus was immobilized onto nano-silica particles to improve its stability and biological performance against the Fusarium solani–Meloidogyne incognita co-infection disease complex. The biological activity of nano-chitinase was evaluated through in vitro antifungal and nematicidal assays as well as greenhouse experiments using tomato plants. The immobilized enzyme exhibited enhanced catalytic activity, thermal stability, pH tolerance, and resistance to inhibitory environmental conditions compared with free chitinase. Nano-chitinase also showed superior antifungal and nematicidal activities, resulting in reduced fungal growth, nematode egg hatching, wilt symptoms, vascular browning, and gall formation under greenhouse conditions. In addition, nano-chitinase treatment was associated with improved plant growth, enhanced soil biochemical activity, reduced oxidative stress, and increased antioxidant enzyme responses in infected tomato plants. These findings suggest that nano-silica immobilization may improve the biological performance and environmental stability of chitinase, supporting its potential as an environmentally friendly biocontrol approach for management of soil-borne pathogen complexes. However, the present findings were obtained under controlled greenhouse conditions, and additional long-term greenhouse and field studies are required to validate its practical agricultural applicability and environmental safety under diverse environmental conditions.