纳米银对四种不同性质土壤微生物量及酶活性的影响

Effects of silver nanoparticles on microbial communities and enzyme activity in four soils

为研究纳米银在土壤中的微生物毒性,采用室内培养方式,探究纳米银(0、10、50、100 mg·kg^(-1))对4种不同性质土壤中微生物数量、多样性、呼吸作用及酶活性的影响。结果显示,低剂量(10 mg·kg^(-1))纳米银对土壤微生物影响较小,中高剂量(50、100 mg·kg^(-1))纳米银处理下土壤可培养微生物数量显著降低。随着纳米银剂量的增加,黄褐土酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、蓝菌门(Cyanobacteria)、硝化螺旋菌门(Nitrospirae)、厚壁菌门(Firmicutes)群落丰度显著下降;变形菌门(Proteobacteria)、浮霉菌门(Planctomycetes)群落丰度显著增加。纳米银处理土壤呼吸作用减弱,土壤脲酶、蔗糖酶活性显著抑制,而荧光素二乙酸酯酶(FDA酶)、过氧化氢酶活性受纳米银剂量影响没有显著变化。同剂量纳米银处理下黄褐土、砖红壤中微生物性状因子对纳米银的响应强于水稻土和黄棕壤。多变量主成分分析显示,纳米银对真菌、FDA酶、过氧化氢酶的抑制与土壤有机质、砂粒含量正相关,对脲酶、蔗糖酶、呼吸作用的抑制与土壤pH值、阳离子交换量(CEC)正相关。综上分析,纳米银进入土壤后会对土壤微生物产生毒性作用,抑制微生物的生长繁殖,但不同门类微生物对纳米银的敏感程度不同,且纳米银的毒性受土壤性质的影响。

In order to evaluate the microbial toxicity of silver nanoparticles（Ag NPs）in soils, incubation experiments were conducted to investigate the effects of Ag NPs（0, 10, 50, and 100 mg·kg^（-1） soil）on microbial biomass, diversity, respiration, and enzyme activity in four different soils. The results showed that a low Ag NP content（10 mg·kg^（-1））had little effect on soil microbes while high contents（50 and 100 mg·kg^（-1））significantly decreased microbial numbers（bacteria, fungi, and actinomycetes）. The richness of the soil bacterial community（Acidobacteria, Actinobacteria, Cyanobacteria, Nitrospirae, and Firmicutes）significantly decreased with increasing Ag NPs content, whereas that of several other phyla（e.g. Proteobacteria and Planctomycetes）increased. The soil urease and invertase activities were significantly inhibited, while fluorescein diacetate（FDA）and catalase activities were not pronouncedly changed by the Ag NPs content. For the same Ag NPs content, the responses of the microbe traits in yellow cinnamon soils and laterite were stronger than those in paddy soil and yellow brown soil.Multivariate principal component analysis suggested that the inhibition of fungi number, FDA enzymes, and catalase activities were positively correlated with soil organic matter and sand contents. The inhibition of urease, invertase activities, and respiration by Ag NPs were positively correlated with soil pH and cation exchange capacity. We conclude that Ag NPs play a toxic role on soil microbes, and inhibit the growth and reproduction of microorganisms. However, the sensitivity of different microbes to Ag NPs is different, and the toxicity of Ag NPs can be affected by soil properties.