Optimization of antagonistic effect of bacillus sp. with response surface methodology

Abstract

The aim of the study was to optimize the culture conditions of the bacteria to increase the antagonist effect of Bacillus pumilus PJ_11 on Vibrio vulnificus. In the study, the antagonistic activity of the whole cell product of Bacillus PJ_11 was tested by the agar well diffusion method. Parameters (temperature, NaCl concentration, and incubation time) of the culture medium were optimized with response surface methodology and evaluated at three different levels. In the experiment designed with the Box Behnken method, it was observed that the inhibitory effect was highest (zone diameter 26.44 mm) at 30 °C, 2% NaCl concentration, and 18th hour. The coefficient values of the response surface regression equation showed that temperature was more effective on the response than other parameters. Additionally, the coefficient values indicated that the combined effect of temperature and NaCl concentration was more effective on the response than other combinations (temperature-incubation time and NaCl concentration-incubation time). The results showed that the Box-Behnken design in three-factor optimization of culture conditions can be used to determine the most effective antagonistic activity of inhibitor bacteria on pathogenic bacteria.