Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California, USA.
Department of Entomology, University of California, Riverside, Riverside, California, USA.
Appl Environ Microbiol. 2019 Oct 16;85(21). doi: 10.1128/AEM.01411-19. Print 2019 Nov 1.
Honey bees are important insect pollinators used heavily in agriculture and can be found in diverse environments. Bees may encounter toxicants such as cadmium and selenate by foraging on plants growing in contaminated areas, which can result in negative health effects. Honey bees are known to have a simple and consistent microbiome that conveys many benefits to the host, and toxicant exposure may impact this symbiotic microbial community. We used 16S rRNA gene sequencing to assay the effects that sublethal cadmium and selenate treatments had over 7 days and found that both treatments significantly but subtly altered the composition of the bee microbiome. Next, we exposed bees to cadmium and selenate and then used untargeted liquid chromatography-mass spectrometry (LC-MS) metabolomics to show that chemical exposure changed the bees' metabolite profiles and that compounds which may be involved in detoxification, proteolysis, and lipolysis were more abundant in treatments. Finally, we exposed several strains of bee-associated bacteria in liquid culture and found that each strain removed cadmium from its medium but that only Firm-5 microbes assimilated selenate, indicating the possibility that these microbes may reduce the metal and metalloid burden on their host. Overall, our report shows that metal and metalloid exposure can affect the honey bee microbiome and metabolome and that strains of bee-associated bacteria can bioaccumulate these toxicants. Bees are important insect pollinators that may encounter environmental pollution when foraging upon plants grown in contaminated areas. Despite the pervasiveness of pollution, little is known about the effects of these toxicants on honey bee metabolism and their symbiotic microbiomes. Here, we investigated the impact of selenate and cadmium exposure on the gut microbiome and metabolome of honey bees. We found that exposure to these chemicals subtly altered the overall composition of the bees' microbiome and metabolome and that exposure to toxicants may negatively impact both host and microbe. As the microbiome of animals can reduce mortality upon metal or metalloid challenge, we grew bee-associated bacteria in media spiked with selenate or cadmium. We show that some bacteria can remove these toxicants from their media and suggest that bacteria may reduce metal burden in their hosts.
蜜蜂是农业中广泛使用的重要昆虫传粉媒介，它们可以在各种环境中生存。蜜蜂在受污染地区觅食时，可能会接触到镉和硒酸盐等有毒物质，从而对其健康产生负面影响。众所周知，蜜蜂具有简单而一致的微生物组，这对宿主有许多好处，而有毒物质的暴露可能会影响这种共生微生物群落。我们使用 16S rRNA 基因测序来检测亚致死剂量的镉和硒酸盐处理对蜜蜂微生物组的影响，发现这两种处理都显著但微妙地改变了蜜蜂微生物组的组成。接下来，我们让蜜蜂接触镉和硒酸盐，然后使用非靶向液相色谱-质谱（LC-MS）代谢组学来表明，化学暴露改变了蜜蜂的代谢物谱，参与解毒、蛋白水解和脂肪分解的化合物在处理中更为丰富。最后，我们在液体培养中暴露了几种蜜蜂相关细菌菌株，发现每种菌株都能从培养基中去除镉，但只有 Firm-5 微生物能够同化硒酸盐，这表明这些微生物可能会减少宿主的金属和类金属负担。总的来说，我们的报告表明，金属和类金属暴露会影响蜜蜂的微生物组和代谢组，并且蜜蜂相关细菌菌株可以生物积累这些有毒物质。蜜蜂是重要的昆虫传粉媒介，在觅食受污染地区生长的植物时可能会接触到环境污染。尽管污染普遍存在，但人们对这些有毒物质对蜜蜂代谢和共生微生物组的影响知之甚少。在这里，我们研究了暴露于硒酸盐和镉对蜜蜂肠道微生物组和代谢组的影响。我们发现，暴露于这些化学物质会微妙地改变蜜蜂微生物组和代谢组的整体组成，并且有毒物质的暴露可能会对宿主和微生物产生负面影响。由于动物的微生物组可以降低金属或类金属挑战的死亡率，我们在含有硒酸盐或镉的培养基中培养蜜蜂相关细菌。我们表明，一些细菌可以从培养基中去除这些有毒物质，并表明细菌可能会减少宿主的金属负担。
