Streptomyces plicatus as a model biocontrol agent

Area of Science:

• Microbiology
• Plant Pathology
• Biotechnology

Background:

• Plant diseases caused by Fusarium oxysporum f.sp. lycopersici, Alternaria alternata, and Verticillium albo-atrum significantly impact tomato yield.
• Chitinase enzymes show potential as biocontrol agents against fungal pathogens.

Purpose of the Study:

• To screen Streptomyces isolates for chitinase production.
• To evaluate the efficacy of chitinase from Streptomyces plicatus against key tomato fungal pathogens.
• To assess the in vivo protective effect of S. plicatus on tomato plants.

Main Methods:

• Isolation and screening of 372 Streptomyces isolates for chitinase activity.
• Optimization of chitinase production conditions for Streptomyces plicatus (3 days, 30°C, pH 8.0, chitin and sucrose, calcium nitrate).
• In vitro inhibition assays against spore germination, germ tube elongation, and radial growth of Fusarium oxysporum f.sp. lycopersici, Alternaria alternata, and Verticillium albo-atrum.
• In vivo protection assay by applying S. plicatus to tomato root systems before transplantation.

Main Results:

• Streptomyces plicatus was identified as the optimal chitinase producer among 372 isolates.
• Optimized conditions yielded maximum chitinase production.
• S. plicatus chitinase demonstrated significant inhibition of spore germination, germ tube elongation, and radial growth of tested phytopathogenic fungi.
• In vivo application of S. plicatus provided marked protection to tomato plants against these fungal pathogens.

Conclusions:

• Streptomyces plicatus is a valuable source of chitinase with potent antifungal properties.
• Chitinase from S. plicatus can be effectively utilized as a biocontrol agent against major tomato diseases.
• This study highlights the potential of S. plicatus for developing sustainable agricultural practices to manage plant pathogens.