Bacterial Agents for Biocontrol of American Foulbrood (AFB) of Larvae Honey Bee

Bee colonies that belong to the biocenosis are constantly threatened by the bacterial larvae disease called American foulbrood, caused by Paenibacillus larvae. The current state of the law prevents the inclusion of pharmacotherapy in the treatment and the only control is based on physical eradication of infected colonies by order of the Vet. The purpose of this study was to investigate the antimicrobial activity of selected bacteria with proven probiotic potential that could reduce American foulbrood pressure by promoting the development of the larvae microbiome that competes with and blocks the excessive proliferation and production of P. larvae endospores. The antimicrobial activity of inoculants of selected strains was studied: B. pumilus, B. licheniformis, S. narbonensis, L. fusiformis, L. brevis, B. megaterium against P. larvae ATCC 9545 and P. larvae CCUG 48973. Analyses were performed by the well-diffusion method according to EUCAST standards with modifications due to the specificity of the bacteria used. The largest zone of growth inhibition of P. larvae was confirmed with: S. narbonensis, B. licheniformis, B. megaterium, medium activity was observed with L. brevis and B. pumilus. Negligible activity was shown by L. fusiformis. Differences were noticed in the resistance of indicator strains of P. larvae and between the media and carriers used.