Development of antibiotic resistant mutants of some antagonistic bacteria and investigation of their antagonistic activity and mechanisms against Rhizoctonia solani, the causal agent of cotton seedling damping-off

Document Type : Research Paper

Authors

• H. Jahanifar
• A. Heydari
• Nader Hasanzadeh1
• L. Naraghi

Abstract

In this study, antibiotic resistant mutants of antagonistic bacteria to Rifampicin and Nalidixic acid using spontaneous mutation were obtained. Antagonistic activity of three isolates belonging to Pseudomonas fluorescens were tested in vitro against a virulent isolate of Rhizoctonia solani, the causal agent of cotton seedling damping-off, using dual culture method. It was shown that two isolates had better antagonistic traits against fungus in comparison with their wild types. The above isolates were also evaluated for their inhibitory mechanisms against fungal pathogen and the results showed that all three mutants were different than their wild types in volatile metabolites production. There were no differences between the mutants and wild types in production of non-volatile metabolites. However, some mutants (Pf-C-1, Pf-W-2) produced more siderophores than their wild types. Results of this study suggest that spontaneous mutation may affect and enhance the activity and performance of antagonistic bacteria.

Keywords

• Antagonistic bacteria
• antibiotic resistant mutants
• inhibitory mechanisms
• cotton seedling damping-off
• Rhizoctonia solani

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