Short-term effects of <i>Brevibacillus laterosporus</i> supplemented diet on worker honey bee microbiome: a pilot study

In the current study, honey bees’ diet was supplemented with spores of <i>Brevibacillus laterosporus</i> BGSP11 at concentration of 10⁸ CFU/ml in sucrose solution and its short-term effects on their micro- and mycobiota have been analyzed using Illumina MiSeq sequencing. Obtained results indicate that this treatment does not lead to potentially harmful changes in the bacterial microbiome of worker bees, slightly affecting the composition of core microbiota. Moreover, several potentially beneficial changes have been observed. The treatment has led to a significant increase in the abundance of <i>Snodgrassella alvi,</i> and species from <i>Lactobacillus</i> and <i>Bifidobacterium</i> genera which play important roles in protection against several honey bee pathogens. Simultaneously, <i>B. laterosporus</i> enriched diet have led to almost complete eradication of <i>Enterobacteriaceae</i> family, the taxon that contains several putative pathogen species. On the other hand, the treatment affected mycobiota more profoundly, which was expected considering the greater instability compared to microbiota. Although the observed changes in honey bee mycobiome cannot be considered <i>a priori</i> beneficial or harmful, since the interaction between the bee and its mycobiome has not been sufficiently studied, certain beneficial consequences of the treatment have been observed. They are primarily reflected in the reduction of phytopathogenic fungi that can affect the organoleptic and techno-functional characteristics of honey. In addition, before introducing <i>B. laterosporus</i> in beekeeping practice as a biological agent for pathogen control it is necessary to perform more thorough studies of the impact on the honey bee microbiome, immune system, physiology and economic characteristics of honey bee colonies.