摘要
      恩施市位于中国湖北省，是世界硒之都，硒资源最丰富。人们发现，一种重要的硒超积累植物——紫叶Cardamine violifolia在这种高硒生态系统中自然生长。然而，人们对硒水平对紫堇根际微生物群落和功能变化的影响知之甚少。在这里，我们检验了地下微生物多样性和功能随硒梯度变化的假设，包括抗生素抗性基因（ARGs）。综合宏基因组分析，如分类学调查、功能检测和ARG注释，表明硒、汞、镉、铅、砷以及有效磷和钾与微生物多样性和功能相关。Thaumarchaeota在矿山露头的最高硒浓度中独家占主导地位，Rhodanobacter和Nitrospira在高硒生态系统中占主导地位。与大块土壤中的硒含量相比，紫堇在根际富集了高浓度的硒，并在根际吸收了Variovorax和Polomonas。微生物丰度呈现出从低硒浓度到高硒浓度先增加后减少的趋势。ARGs的注释显示，多药耐药基因adeF、mtrA和poxtA、氨基糖苷类耐药基因rpsL和磺酰胺类耐药基因sul2在高硒系统中富集。研究发现，假定的抗生素抗性细菌在不同硒浓度的农田和土壤中表现出明显的差异，这表明高硒生态系统中含有具有更高富集或抵抗硒、有毒金属或抗生素能力的特定微生物。总之，这些结果揭示了硒浓度和硒超积累植物C.violifolia对微生物功能群落和ARGs形成的影响。类金属硒诱导的抗生素耐药性值得关注。
Abstract
Enshi City, in the Hubei Province of China, is known as the world capital of selenium with the most abundant selenium resource. An important selenium hyperaccumulator plant, Cardamine violifolia, was found to naturally grow in this high-selenium ecosystem. However, relatively little is known about the impact of the selenium levels on microbial community and functional shifts in C. violifolia rhizosphere. Here, we tested the hypothesis that underground microbial diversity and function vary along a selenium gradient, including antibiotic resistance genes (ARGs). Comprehensive metagenomic analyses, such as taxonomic investigation, functional detection, and ARG annotation, showed that selenium, mercury, cadmium, lead, arsenic, and available phosphorus and potassium were correlated with microbial diversity and function. Thaumarchaeota was exclusively dominant in the highest selenium concentration of mine outcrop, and Rhodanobacter and Nitrospira were predominant in the high-selenium ecosystem. The plant C. violifolia enriched a high concentration of selenium in the rhizosphere compared to those in the bulk soil, and it recruited Variovorax and Polaromonas in its rhizosphere. Microbial abundance showed a trend of increasing first and then decreasing from low to high selenium concentrations. Annotation of ARGs showed that the multidrug resistance genes adeF, mtrA, and poxtA, the aminoglycoside resistance gene rpsL, and the sulfonamide resistant gene sul2 were enriched in the high-selenium system. It was discovered that putative antibiotic resistant bacteria displayed obvious differences in the farmland and the soils with various selenium concentrations, indicating that a high-selenium ecosystem harbors the specific microbes with a higher capacity to enrich or resist selenium, toxic metals, or antibiotics. Taken together, these results reveal the effects of selenium concentration and the selenium hyperaccumulator plant C. violifolia on shaping the microbial functional community and ARGs. Metalloid selenium-inducible antibiotic resistance is worth paying attention to in future.

https://www.sciencedirect.com/science/article/abs/pii/S0045653522033513