College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
College of Plant Protection, China Agricultural University, Beijing, China.
Insect Sci. 2021 Apr;28(2):302-314. doi: 10.1111/1744-7917.12770. Epub 2020 Sep 9.
Bumblebees play an important role in maintaining the balance of natural and agricultural ecosystems, and the characteristic gut microbiota of bumblebees exhibit significant mutualistic functions. China has the highest diversity of bumblebees; however, gut microbiota of Chinese bumblebees have mostly been investigated through culture-independent studies. Here, we analyzed the gut communities of bumblebees from Sichuan, Yunnan, and Shaanxi provinces in China through 16S ribosomal RNA amplicon sequencing and bacterial isolation. It revealed that the bumblebees examined in this study harbored two gut enterotypes as previously reported: one is dominated by Gilliamella and Snodgrassella, and the other is distinguished by prevalent environmental species. The gut compositions obviously varied among different individual bees. We then isolated 325 bacterial strains and the comparative genomic analysis of Gilliamella strains revealed that galactose and pectin digestion pathways were conserved in strains from bumblebees, while genes for the utilization of arabinose, mannose, xylose, and rhamnose were mostly lost. Only two strains from the Chinese bumblebees possess the multidrug-resistant gene emrB, which is phylogenetically closely related to that from the symbionts of soil entomopathogenic nematode. In contrast, tetracycline-resistant genes were uniquely present in three strains from the USA. Our results illustrate the prevalence of strain-level variations in the metabolic potentials and the distributions of antibiotic-resistant genes in Chinese bumblebee gut bacteria.
大黄蜂在维持自然和农业生态系统的平衡方面发挥着重要作用，大黄蜂的特征性肠道微生物群表现出显著的互利功能。中国拥有最多样化的大黄蜂；然而，中国大黄蜂的肠道微生物群大多是通过非培养研究进行调查的。在这里，我们通过 16S 核糖体 RNA 扩增子测序和细菌分离分析了来自中国四川、云南和陕西三省的大黄蜂的肠道群落。结果表明，本研究中检查的大黄蜂具有先前报道的两种肠道肠型：一种以 Gilliamella 和 Snodgrassella 为主导，另一种以普遍存在的环境物种为特征。不同个体大黄蜂的肠道组成明显不同。然后，我们分离了 325 株细菌，对 Gilliamella 菌株的比较基因组分析表明，在来自大黄蜂的菌株中，半乳糖和果胶消化途径是保守的，而用于利用阿拉伯糖、甘露糖、木糖和鼠李糖的基因则大多丢失。只有来自中国大黄蜂的两个菌株具有多药耐药基因 emrB，该基因在系统发育上与土壤昆虫病原线虫共生体中的基因密切相关。相比之下，来自美国的三个菌株中独特地存在四环素耐药基因。我们的研究结果表明，中国大黄蜂肠道细菌在代谢潜力和抗生素耐药基因分布方面存在菌株水平的变异。
