四川省稻田土壤的抗生素抗性基因多样性研究

Diversity of antibiotic resistance genes in paddy soils in Sichuan Province,China

为了全面明晰四川省稻田土壤中抗生素抗性基因的丰度和多样性,及其与环境因子的相关性,对7个不同地区的稻田土壤采用高通量荧光定量PCR技术,对283种抗生素抗性基因和12种可移动遗传元件遗传标记引物进行检测,揭示抗性基因的污染状况及空间分布规律。结果表明,7个稻田土中共检出166种不同的抗生素抗性基因和9种可移动遗传元件,每个土壤分别检出56~84种抗生素抗性基因。7个稻田土的抗生素抗性基因组成各异,且都存在其独有的抗生素抗性基因。不同稻田土的抗生素抗性基因的相对和绝对丰度均不同,抗生素抗性基因的绝对丰度范围为9.55×10^8~2.83×10^10 copies·g^-1(干质量),相对丰度为0.012±0.006 copies·cell^-1。7个稻田土的抗生素抗性基因和可移动遗传元件的丰度都呈极显著正相关(P<0.01),说明抗生素抗性基因的水平转移可能促进抗生素抗性基因的迁移和富集,加剧了农田土壤的抗生素抗性基因污染。总体相对丰度较高的抗生素抗性基因类型为多重耐药类(49.26%)、大环内脂类-林可酰胺类-链阳性菌素B类(11.30%)和β-内酰胺类(10.87%)。冗余分析表明土壤肥力重要指标总氮与7个稻田土中的抗生素抗性基因多样性极显著相关(P<0.01)。四川不同地区的稻田土抗生素抗性基因分布规律各异,农业耕种活动可能影响土壤抗生素抗性基因的多样性。

To clarify the abundance and diversity of antibiotic resistance genes(ARGs)and their correlation with environmental factors in Sichuan Province,a high-throughput quantitative PCR technique(HT-qPCR)was performed on seven geographically separated paddy soils using 283 ARGs and 12 mobile genetic elements(MGEs)primers sets.The results showed that a total of 166 ARGs and 9 MGEs were detected in all seven paddy soils,with a range of 56~84 ARGs in each soil.The ARGs profiles in the seven paddy soils varied in their compositions and dominant ARGs types,and each soil contained their unique ARG sub-types.The relative abundance and absolute abundance of ARGs among paddy soils were different.The ARGs copy number ranged from 9.55×10^8 to 2.83×10^10 copies·g^-1(dry soil),and the relative gene copy number was 0.012±0.006 copies·cell^-1.The abundance of ARGs was significantly correlated(P<0.01)with that of MGEs,which suggests that horizontal gene transfer could play a vital role in the propagation and enrichment ARGs in agricultural soils.The top three ARGs types with relatively higher abundances were multidrug resistant(49.26%),macrolides–lincosamides–streptavidin B(MLSB)(11.30%),and beta lactamase(10.87%).Redundant analysis showed that total nitrogen,an important indicator of soil fertility,was significantly correlated with ARGs profiles in the seven paddy soils(P<0.01).In summary,a regional difference in ARGs patterns was observed in the Sichuan province.The distinct distribution patterns of ARGs among different paddy soils may be influenced by farmland managements.The implication of this study is that it can be used to objectively assess agricultural environmental risks of ARGs.