Inhibition of Erwinia amylovora by Bacillus nakamurai

A variety of potential inhibitors were tested for the first time for the suppression of Erwinia amylovora , the causal agent of fire blight in apples and pears. Strain variability was evident in susceptibility to inhibitors among five independently isolated virulent strains of E. amylovora . However, most strains were susceptible to culture supernatants from strains of Bacillus spp., and particularly to the recently described species B. nakamurai . Minimal inhibitory concentrations (MICs) were 5–20% (vol/vol) of culture supernatant from B. nakamurai against all five strains of E. amylovora . Although Bacillus species have been previously reported to produce lipopeptide inhibitors of E. amylovora, matrix-assisted laser desorption time of flight mass spectrometry (MALDI-TOF MS) and column chromatography indicated that the inhibitor from B. nakamurai was not a lipopeptide, but rather a novel inhibitor.