环境因素对土壤中几种典型四环素抗性基因形成的影响

Effect of Environmental Factors on the Formation of Several Typical Tetracycline Resistance Genes in Soil

兽用四环素在养殖业中的大量使用导致了日益严重的环境污染,其诱导生成的抗性基因更可能产生比其自身污染更大的环境危害.本研究探讨了环境因素对几种典型四环素抗性基因(tetA、tetC)形成的影响,结果表明,温度、光照及pH能够对土壤中四环素抗性基因的形成产生显著的影响,在较为合适的温度条件(25℃)、光照条件(500 lx)和pH(7.5)条件下,土壤中四环素耐药菌菌落数和四环素抗性基因总含量均处于较高的水平,并多显著高于其他环境条件下的诱导水平(P<0.05),而高温、强光照及较高的pH条件能够有效抑制土壤中四环素抗性基因的形成,抑制的主要途径可能包括影响土壤中四环素的残留水平或直接影响抗性基因的生成,同时研究也发现这些不利的环境条件也抑制了土壤中四环素耐药菌的生长.进一步分析在两种不同通气处理条件下土壤中所诱导产生的四环素抗性基因含量水平与土壤中四环素耐药菌数量之间的关系,发现在两种条件下四环素抗性基因含量水平与土壤中四环素耐药菌数量之间存在着较为显著的正相关关系(R2好氧=0.7872,n=30;R2缺氧=0.8841,n=21),土壤中四环素耐药菌的生长对四环素抗性基因的形成也起到了关键性作用.

The extensive use of veterinary tetracycline in the stock husbandry has led to the increasingly serious environmental pollution, the tetracycline resistance genes induced by which could bring more hazardous environmental risk than veterinary tetracycline. This study investigated the effects of environmental factors on the formation of several typical tetracycline resistance genes (tetA, tetC). The results showed that temperature, light and pH could have impacts on the formation of tetracycline resistance genes in soil, the amounts of the tetracycline resistance bacteria and resistance genes induced in different treatments all reached the maximum in the proper environmental condition (25℃, 500 lx, pH7. 5), which were all significantly higher than those in other environmental conditions(P 《 0. 05). In contrast, the adverse condition such as high temperature, strong light and high pH could effectively inhibit the formation of tetracycline resistance genes, probably due to the reduction of tetracycline residues or the direct influence on the formation of tetracycline resistance genes. And the results also showed that environmental factors could affect the growth of tetracycline resistance bacteria. Further analysis proved that the content of tetracycline resistance gene in soil had a positive correlation with the number of tetracycline resistance bacteria in the studied samples, therefore an inferred result was concluded that the growth of tetracycline resistance bacteria played a key role in the formation of the tetracycline resistance genes.