Potentiation effect of the AI-2 signaling molecule on postharvest disease control of pear and loquat by Bacillus amyloliquefaciens and its mechanism

An autoinducer-2 (AI -2) signaling molecule from Bacillus was synthesized, and its mechanism on the biofilm formation and biocontrol ability of B. amyloliquefaciens was verified in vitro and in vivo. The 16S/ITS amplicon sequencing was used to analyze the effect of B. amyloliquefaciens B4 with or without AI -2 on the microflora of pears during storage. The results showed that B. amyloliquefaciens B4 secreted AI -2, which promoted biofilm formation. Additionally, AI -2 at a concentration of 40 mu mol/L enhanced the biocontrol ability of B. amyloliquefaciens B4 on postharvest pear and loquat fruits. Finally, amplicon sequencing demonstrated that the addition of AI -2 increased the abundance of B. amyloliquefaciens B4 in fruit by stimulating the growth and biofilm formation of this bacterium.