Characterization of Bacillus Amyloliquefaciens Strain N23 for Controlling Potato Common Scab

Potato common scab is a soilborne disease caused by Streptomyces spp., which has been a serious problem in potato production, with S. galilaeus being predominant in Inner Mongolia of China. To obtain highly effective biocontrol agents for controlling common scab, 53 antagonistic bacteria were examined on the suppression of Streptomyces spp. on agar plates. Among them, strain N23 had the best performance, which inhibited 82.74% growth of S. galilaeus and its derived metabolites inhibited the growth of S. galilaeus by 69.23%. Therefore, N23 was chosen for further study in greenhouse and field trials. In greenhouse trials, N23 increased potato emergence and promoted the growth of potatoes, and controlled common scab by 58.41%. In two field trials, seed treatment with N23 resulted in 74.26% to 61.60% disease control, and 8.41% to 14.20% yield increase. Soil treatment with N23 had 64.56% to 53.30% disease control and 3.08% to 11.00% yield increase. N23 was identified as Bacillus amyloliquefaciens on the basis of morphological, physiological, and biochemical characteristics, as well as sequence analysis of the 16S rDNA and gyrA. Optimal conditions for N23 growth included soluble starch as a carbon source, ammonium nitrate as a nitrogen source, pH 7.5, and temperature at 32℃. Thus, N23 can be a candidate for a biological control agent.