Isolation and Identification of A Soil Bacterial Strain Efficiently Inhibiting Ralstonia solanacearum in Tobacco Field

A bacterial strain,which was isolated from the healthy soil sample in Qianjiang tobacco district of Chongqing city,was found to possess obvious inhibitory action on Ralstonia solanacearum in tobacco.Flat confrontation test showed that the bacterial strain against Ralstonia solanacearum had the inhibition zone of 28.9 mm in diameter.In the further study,the extracellular products of the strain were crudely extracted and taken liveness detection.The diameter of inhibition zone of the crude extract at the concentration of 250 μg per piece was 15.5 mm tested by filter paper method.IC50 of the crude extract was 342 μg/mL by MIC method,and the inhibition ratio decreased with the extension of time,but still keeping above 70% 3 days later.According to the morphological characteristics,culture character,cellular fatty acid and 16S rDNA sequence analysis of this bacterial strain,it was identified to be Pseudomonas aeruginosa.