摘要

       冰川退缩前陆植物群落和微生物群落的初步演替已被广泛研究，但由于全球变暖，随着冰川退缩，抗药性基因（ARGs）的转移仍不清楚。揭示冰川退却过程中原始土壤中ARGs的多样性和演替特征，有助于对土壤抗逆性演化和发展的机制性认识。本研究采用高通量定量PCR（HT qPCR）技术，对50年土壤发育时间序列中ARGs的丰度和多样性进行了定量分析。在所有冰川样品中，共检测到24个ARGs和2个移动遗传元素（mge），发现ARGs的数量在早期（0∼8年）呈单峰型增长，但在后期（17∼50年）无显著变化。oprJ和mexF基因编码的多药耐药是所有演替年龄中唯一检测到的两个arg，mexF基因在演替时间上呈上升趋势。结构方程模型表明，编码1类整合子整合酶的intI1基因在形成精氨酸分布变异中起主导作用。这些结果表明，在没有人为影响的原始土壤中存在ARGs，MGEs介导的水平基因转移可能有助于ARGs在土壤形成初期沿时间序列的演替模式。

        Primary succession of plant and microbial communities in the glacier retreating foreland has been extensively studied, but shifts of antibiotic resistance genes (ARGs) with the glacier retreating due to global warming remain elusive. Unraveling the diversity and succession features of ARGs in pristine soil during glacier retreating could contribute to a mechanistic understanding of the evolution and development of soil resistome. In this study, we quantified the abundance and diversity of ARGs along a 50-year soil development chronosequence by using a high-throughput quantitative PCR (HT-qPCR) technique. A total of 24 ARGs and two mobile genetic elements (MGEs) were detected from all the glacier samples, and the numbers of detected ARGs showed a unimodal pattern with an increasing trend at the early stage (0∼8 years) but no significant change at later stages (17∼50 years). The oprJ and mexF genes encoding multidrug resistance were the only two ARGs that were detected across all the succession ages, and the mexF gene showed an increasing trend along the succession time. Structural equation models indicated the predominant role of the intI1 gene encoding the Class 1 integron-integrase in shaping the variation of ARG profiles. These findings suggested the presence of ARGs in pristine soils devoid of anthropogenic impacts, and horizontal gene transfer mediated by MGEs may contribute to the succession patterns of ARGs during the initial soil formation stage along the chronosequence.

       https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629927/