Large-scale Culture and Preservation Methods of Pseudomonas cepacia B5 for Biological Control against Bacterial Wilt Disease

Bacterial wilt disease is one of the most troublesome diseases that plague tobacco and other plants of the Solanaceae family. A variety of agricultural chemicals have been used to try to prevent it, but the environmental damage caused by chemical residues in the soil has become a serious concern. And so biological control techniques are now being studied using strains antagonistic to its pathogen Pseudomonas solanacearum, such as an avirulent strain of P. solanacearum M4S, bacteriocin producing strains of P. solanacearum OM1 and OM2, and an antimicrobial substance-producing strain of Pseudomonas cepacia B5. Among these strains, P. cepacia B5, isolated from rice paddy soil, has been found to suppress the incidence of bacterial wilt disease in tobacco and tomato when applied to a flooded field mixed with wheat bran. In the paddy, P. cepacia B5 produces 2-Keto-D-gluconic acid from the glucose residue of wheat bran, and it is this acid that inhibits the growth of the pathogen. Before the field tests, the antimicrobial activity of P. cepacia B5 against the pathogen was confirmed on agar plates and in suspension cultures, without wheat bran or soil.