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.本研究以蔗糖溶液为载体，添加浓度为10⁸ CFU/ml的侧孢短芽孢杆菌（Brevibacillus laterosporus）BGSP11菌株孢子，对蜜蜂的细菌微生物群落（microbiota）与真菌群落（mycobiota）的短期影响开展Illumina MiSeq测序（Illumina MiSeq Sequencing）分析。 研究结果显示，该处理不会引发工蜂细菌微生物群落出现潜在有害变化，仅对核心微生物群落的组成产生轻微影响。此外，本研究还观测到多项潜在有益变化：该处理显著提升了阿尔维斯诺德格拉斯菌（Snodgrassella alvi）、乳杆菌属（Lactobacillus）以及双歧杆菌属（Bifidobacterium）物种的丰度——这些类群在抵御多种蜜蜂病原菌方面发挥关键作用。与此同时，添加侧孢短芽孢杆菌的饲粮可几乎完全清除肠杆菌科（Enterobacteriaceae）类群，该类群包含多种疑似病原菌物种。 另一方面，该处理对真菌群落的影响更为显著，这一结果符合预期，因真菌群落相较于细菌微生物群落稳定性更差。尽管蜜蜂与其真菌群落间的互作机制尚未得到充分研究，无法先验地（a priori）判定蜜蜂真菌组（mycobiome）的观测变化是有益还是有害，但本研究仍观测到该处理带来了若干有益结果，主要体现为可影响蜂蜜感官品质与工艺功能特性的植物病原真菌丰度降低。 此外，若要将侧孢短芽孢杆菌作为病原菌防控的生物制剂应用于养蜂实践，还需开展更深入的研究，以评估其对蜜蜂微生物群落、免疫系统、生理机能以及蜂群经济性状的影响。