INTERACTION OF DIFFERENT MEDIA ON PRODUCTION AND BIOCONTROL EFFICACY OF PSEUDOMONAS FLUORESCENS P35 AND BACILLUS SUBTILIS B3 AGAINST GREY MOULD OF APPLE
S. Peighami-Ashnaei, A. Sharifi-Tehrani, M. Ahmadzadeh, K. Behboudi
In this study, growth and efficacy of two biological control agents, Pseudomonas fluorescens P-35 and Bacillus subtilis B-3, were evaluated in combinations of two carbon (sucrose and molasses) and two nitrogen (urea and yeast extract) sources to optimize control of Botrytis cinerea on apple. Nutrient broth was used as control. Results indicated that the medium containing molasses and yeast extract (MY) in a 1:1 w/w ratio supported rapid growth and high cell yields in both strains. The biocontrol efficacy of P-35 grown in MY was higher than when grown in the other media, and the percentage of decayed fruits was 38.6% as compared to the control (100%), after ten days incubation. P-35 also showed good biocontrol efficacy in MY after 20 days. Nutrient broth resulted in poor biocontrol efficacy for B-3 after ten days, as compared with the other media. For both strains molasses were a good carbon source in combination with yeast extract, but antagonist growth was decreased when molasses were complemented with urea. The results obtained could provide a reliable basis for mass multiplication of biocontrol agents in fermentation processes.