Production of biocontrol agents using Bacillus sp. in a laboratory-scale bioreactor

Abstract

Biological control by microbial biopesticides, i.e. microbial cells or their metabolites, represents a potentially convenient and environment-friendly alternative to chemical pesticides, the excessive use of which has led to soil deterioration, environmental pollution and considerable concerns for human health. This study has investigated the possibility of biocontrol agent production using Bacillus sp. cultivated in a laboratory-scale bioreactor, which ensured temperature regulation (28°C) as well as the appropriate aeration (1 vvm) and mixing (250 rpm) rates of cultivation broth during the cultivation process (96 h). The cultivation broth samples were tested in vitro, using the diffusion-disc method, against three phytopathogenic isolates: two Xanthomonas campestris strains isolated from cabbage and the Xanthomonas campestris pv. vesicatoria strain isolated from pepper. Maximum inhibition zone diameters were obtained after 96 h of cultivation for each isolate, indicating that Bacillus sp. has enormous potential for further investigation and possible application as a biocontrol agent against the phytopathogens tested.

Keywords

• biocontrol
• microbial biopesticides
• bacillus
• xanthomonas campestris
• bioreactor