Isolation and Identification of Bacillus Subtilis and Pseudomonas Fluorescens from Wheat Rhizosphere and Their Use as Biocontrol Agents

Abstract

Some bacteria may be used as biocontrol agents against fungal pathogens. Biocontrol agents are environment friendly and cost effective for controlling different plant pathogens. Fungal plant pathogens cause detrimental effects on plants causing diseases and yield loss. The bacterial strains Pseudomonas fluorescens and Bacillus subtilis live abundantly in rhizospheric soil and have antagonistic activity against other organisms. The objective of present study was to isolate and identify the Pseudomonas fluorescens and Bacillus subtilis from rhizospheric soil of Triticum aestivum and their use as biocontrol agents against Fusarium oxysporum and Botrytis cinerea. The culture method, microscopic analysis and biochemical methods were used for initially screening of bacteria strain found in rhizospheric soil of Triticum aestivum. The biochemical and molecular tests resulted in the identification of Pseudomonas fluorescens and Bacillus from rhizospheric soil of Triticum aestivum. 16s rRNA sequence analysis confirmed the presence of Bacillus subtilis and Pseudomonas fluorescens. Biocontrol activities of Pseudomonas fluorescens and Bacillus were visualized on potato dextrose agar “PDA” + 0.5% yeast extract plate. Bacillus subtilis showed the maximum biocontrol activity against Fusarium oxysporum and Botrytis cinerea. Pseudomonas fluorescens showed activity against Fusarium oxysporum but did not show any activity against Botrytis cinerea. Bacillus subtilis and Pseudomonas fluorescens inhibited the development of plant pathogenic fungi Fusarium oxysporum and Botrytis cinerea. Bacillus subtilis and Pseudomonas fluorescens may be used as biofertilizer and biopesticides.