微塑料和多种抗生素胁迫下土壤环境因子的响应特性

Response characteristics of soil environmental factors under the stress of microplastics and antibiotics

为了深入探究微塑料(microplastics,MPs)、抗生素胁迫下土壤环境因子产生的响应特性,以聚乙烯(polyethylene,PE)、四环素(tetracycline,TC)、环丙沙星(ciprofloxacin,CIP)为研究对象,通过单独、联合施用到土壤中4周后,开展了土壤的理化性质、酶活性、抗生素残留、抗生素抗性菌(antibiotics resistant bacteria,ARB)抗性、抗生素抗性基因(antibiotic resistance genes,ARGs)、微生物群落的多样性等方面研究.结果显示,施用MPs与抗生素的容重比对照组分别增大了12.3%、16.9%、 21.8%.有机质含量由39.96g·kg^(-1)变化为53.21g·kg^(-1),与对照组相比分别增大了9.16%、12.39%、14.09%、18.47%、32.03%、33.16%、36.04%.阳离子交换量由对照组的44.36 cmol·kg^(-1)显著变化为62.45 cmol·kg^(-1),与对照组相比分别增大了24.06%、30.09%、33.97%、36.49%、47.14%、50.93%、56.1%.实验各组pH值在7.58—8.12之间变化.实验各组的过氧化氢酶含量分别为1.653、 1.559、1.421、1.486、1.376、1.545、1.524、1.453 IU·g^(-1);脲酶含量分别为89.56、78.32、64.65、66.79、57.27、72.31、 71.26、 61.56IU·g^(-1);蔗糖酶含量分别为158.69、 149.61、 134.56、 131.87、 123.65、 137.26、136.83、 126.34 IU·g^(-1). MPs-TC-CIP组的过氧化氢酶活性、脲酶活性、蔗糖酶活性分别下降12.1%、32.3%、26.7%. MPs-TC、MPs-CIP组与TC、CIP实验组相比,抗生素残留量有所降低,分别为187.1%、189.3%;MPs-TC-CIP实验组的抗生素残留则低于单一施用CIP、TC组,分别为182.6%、178.7%.筛选的TC抗性菌(TC resistant bacteria,TCRB)和CIP抗性菌(CIP resistant bacteria,CIPRB)的抗性增加2倍以上. MPs-TC-CIP组与对照组相比,tet W、tet O的相对丰度比值分别为1.82、1.78;qnr A、qnr S的相对丰度比值分别为1.68、1.71.各组中相对丰度较高菌群依次为变形菌(Proteobacteria),放线菌(Actinobacteria)、酸杆菌(Acidobacteria)、芽单胞菌(Gemmatimonadetes)、厚壁菌(Fimicutes).施用抗生素、MPs后Proteobacteria、Actinobacteria相对丰度增加、myxococcus相对丰度减少.研究结果表明,施用MPs能促进抗生素的富集;在共同胁迫下,对土壤理化特性和生物特性影响更为显著,进一步探明了MPs对抗生素残留、ARGs传播、微生物群落演化特征等潜在影响,以期为消减污染物的危害、构建综合智能修复体系提供依据.

In order to investigate the effects of microplastics and antibiotics on the response characteristics of soil environmental factors,MPs,Tetracycline(TC)and Ciprofloxacin(CIP)were applied into soil for 4 weeks separately or jointly.In this experiment,a large number of studies were carried out,such as the physicochemicalof soil,enzyme activity,antibiotic residues,resistance of antibiotics resistant bacteria(ARB),the antibiotic resistance genes(ARGs)and the diversity of microbial community.As a results,the unit weight of soil were increased 12.3%,16.9%and 21.8%,respectively.Compared with the control group,the content of organic matter were changed from 39.96 g·kg^(-1) to 53.21 g·kg^(-1) by PE and antibiotic.They were increased 9.16%,12.39%,14.09%,18.47%,32.03%,33.16%and 36.04%,respectively.So the cation exchange capacity was significantly changed from 44.36 cmol·kg^(-1) to 62.45 cmol·kg^(-1),and they were increased 24.06%,30.09%,33.97%,36.49%,47.14%,50.93%and 56.1%,respectively.The pH of each group varied from 7.58 to 8.12.The catalase of each group were 1.653,1.559,1.421,1.486,1.376,1.545,1.524,1.453 IU·g^(-1),respectively.The urease activity of soil was 89.56,78.32,64.65IU·g^(-1),66.79,1.57.27,72.3,71.26 and 61.56 IU·g^(-1),respectively.The sucrase activities were 158.69,149.61,134.56,131.87,123.65,137.26,136.83 and 126.34 IU·g^(-1),respectively.The activity of catalase,urease and sucrase with MPs and two antibiotics were reduced 12.1%,32.3%and 26.7%,respectively.Compared with the control group,the residues of antibiotics were 187.1%and 189.3%by MPs-TC and MPs-CIP,respectively.Additionally,they were lower than the control group,182.6%and 178.7%by MPs-TC-CIP,respectively.The relative abundance ratios of tet W and tet O were 1.82 and 1.78,respectively.And the relative abundance ratios of qnr A and qnr S were 1.68 and 1.71,respectively.The relative abundance of microbial community were followed by Proteobacteria,Actinobacteria,Acidobacteria,Gemmatimonadetes and Fimicutes.After the application of antibiotics and MPs,the relative abundance of Proteobacteria and Actinobacteria were increased,while the relative abundance of Myxococcus were decreased.The results showed that MPs could promote the enrichment of antibiotics.Under co-stress with MPs-TC-CIP,the effect of physical,chemical and biological characteristics on soil were more significant than the MPs,TC,and CIP alone or mixed.Furtherly,the potential effects of MPs on were explored,such as antibiotic residues,transmission of ARGs and the microbial community diversity,which were laid a foundation for reducing the harm of pollutants and building a comprehensive intelligent remediation system.