Rothman Jason A, Leger Laura, Graystock Peter, Russell Kaleigh, McFrederick Quinn S
Graduate Program in Microbiology, University of California, Riverside, CA, 92521, USA.
Department of Entomology, University of California, Riverside, CA, 92521, USA.
Environ Microbiol. 2019 Sep;21(9):3417-3429. doi: 10.1111/1462-2920.14641. Epub 2019 May 14.
Bumble bees are important and widespread insect pollinators who face many environmental challenges. For example, bees are exposed to the metalloid selenate when foraging on pollen and nectar from plants growing in contaminated soils. As it has been shown that the microbiome of animals reduces metalloid toxicity, we assayed the ability of the bee microbiome to increase survivorship against selenate challenge. We exposed uninoculated or microbiota-inoculated Bombus impatiens workers to a field-realistic dose of 0.75 mg l selenate and found that microbiota-inoculated bees survive slightly but significantly longer than uninoculated bees. Using 16S rRNA gene sequencing, we found that selenate exposure altered gut microbial community composition and relative abundance of specific core bacteria. We also grew two core bumble bee microbes - Snodgrassella alvi and Lactobacillus bombicola - in selenate-spiked media and found that these bacteria grew in the tested concentrations of 0.001-10 mg l selenate. Furthermore, the genomes of these microbes harbour genes involved in selenate detoxification. The bumble bee microbiome slightly increases survivorship when the host is exposed to selenate, but the specific mechanisms and colony-level benefits under natural settings require further study.
大黄蜂是重要且分布广泛的昆虫传粉者，面临着许多环境挑战。例如，蜜蜂在受污染土壤中生长的植物上采集花粉和花蜜时会接触到类金属硒酸盐。由于已有研究表明动物的微生物群可降低类金属毒性，我们测定了蜜蜂微生物群增强抵御硒酸盐挑战的生存能力。我们将未接种或接种了微生物群的熊蜂工蜂暴露于0.75毫克/升的硒酸盐田间实际剂量下，发现接种了微生物群的蜜蜂存活时间略长但显著长于未接种的蜜蜂。通过16S rRNA基因测序，我们发现硒酸盐暴露改变了肠道微生物群落组成以及特定核心细菌的相对丰度。我们还在添加了硒酸盐的培养基中培养了两种熊蜂核心微生物——斯氏蜜蜂肠道菌和熊蜂乳杆菌，发现这些细菌能在0.001 - 10毫克/升的测试硒酸盐浓度下生长。此外，这些微生物的基因组含有参与硒酸盐解毒的基因。当宿主暴露于硒酸盐时，熊蜂微生物群会略微提高其生存能力，但在自然环境下的具体机制和群体水平效益仍需进一步研究。
