Identification of honeybee peptide active against Paenibacillus larvae larvae through bacterial growth-inhibition assay on polyacrylamide gel

The inhibition bands showing activity against Gram-positive bacteria were detected by analyses of acidic extracts of honeybee heads, thoraxes, and royal jellies (RJs) using a bacterial growth-inhibition assay on polyacrylamide gel. The presence of antibacterial peptide royalisin and another unknown peptide was found in two detected RJ inhibition bands by N-terminal sequencing. The data suggested that royalisin was the peptide responsible for the activity against Paenibacillus larvae larvae and other tested Gram-positive bacteria. The analyses of RJs collected from individual colonies at two apiaries, one of which showed incidence of American foulbrood, revealed differences in the content of the antibacterial peptide. The results suggest that the differences might be associated with genetic variability between colonies.