A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its
activity in reducing postharvest decay of peanut kernels caused by Aspergillus flavus in in vitro and in vivo
tests. The results showed that the concentrations of antagonist had a significant effect on biocontrol
effectiveness in vivo: when the concentration of the washed bacteria cell suspension was used at
1×109 CFU/ml, the percentage rate of rot of peanut kernels was 31.67%±2.89%, which was markedly lower
than that treated with water (the control) after 7 days of incubation at 28 °C. The results also showed that
unwashed cell culture of B. megaterium was as effective as the washed cell suspension, and better biocontrol
was obtained when longer incubation time of B. megaterium was applied. When the incubation time of
B. megaterium was 60-h, the rate of decay declined to 41.67%±2.89%. Furthermore, relative to the expression
of 18S rRNA, the mRNA abundances of aflR gene and aflS gene in the experiment group were 0.28±0.03 and
0.024±0.005 respectively, indicating that this strain of B. megaterium could significantly reduce the
biosynthesis of aflatoxins and expression of aflR gene and aflS gene (p