Evaluation of Lactic Acid Bacteria Isolated from the Honey Bee Apis mellifera L. for the Control of the American Foulbrood Disease

Abstract

The purpose of this study is to investigate a new applicable, reliable, promising and highly effective treatment for American Foulbrood (AFB) disease in honey bee colonies. Some of the honey bee gut microbial diversity in worker bees using 560 amplicon assays of the 16S rRNA gene were investigated. The presence of nine novel anaerobic lactic acid bacterial (LAB) flora were reported within honey bee gut. Four of the LABs are carefully related to four different strains of Lactobacillus plantarum species. Two are closely identical to two different strains of Lactobacillus kunkeei species. One is closely related to a strain of Lactobacillus pentosus species. The last two are matching two different strains of Lactobacillus sp.. A strong inhibitory effect of the honey bee stomach LAB flora on AFB bacterial pathogen, Paenibacillus larvae larvae (P. l. larvae) growth in vitro were demonstrated. The individual LAB phylotypes showed different inhibition zones ranges from 0.4 to 1.8 cm. Artificial infection was accompanied by the administration of a mixture of five of the most effective endogenous LABs, previously tested for their inhibitory effect on agar plates in vitro. It was observed that the honey bee endogenous LAB inhibited P. l. larvae in an in vivo system. LAB mixture added to the larval food in honey bee colonies significantly reduced the number of infected larvae when pooled data from all experiments were analyzed (P ≃ 0.000, P < 0.001). Confidence intervals analysis on the effect of the time LAB was added to the colony didn’t show significant different from adding LAB to the food on first or second day post infection and throughout the feeding period. Both in vitro and in vivo studies demonstrated that the LAB microbiota in Apis mellifera inhibit one important honey bee pathogen, the bacterial brood pathogen