重金属污染对土壤微生物生态特征的影响研究进展

Effect of Heavy Metals Pollution on Ecological Characteristics of Soil Microbes: A Review

土壤中微生物对重金属胁迫的敏感程度大于动物和植物,因此,可以利用土壤微生物生态特征的变化来预测土壤环境质量的变化,将其作为评估土壤污染状况的重要指标。论文归纳了重金属污染对土壤微生物的影响及作用机制的研究现状,主要从微生物生物量、微生物群落结构/功能和多样性、微生物耐性基因/蛋白质和代谢能力、土壤呼吸强度和酶活性等几个方面进行了评述。研究表明,重金属污染对土壤微生物生态特征的影响结果存在差异,有促进作用、抑制作用或无明显影响。这是由于土壤微生物体系比较复杂、重金属种类和浓度以及土壤理化性质的差异引起的。近年来,分子生物学的快速发展,使重金属污染胁迫与土壤微生物生态特征变化的关系的研究不断取得新的进展,尤其是在对微生物群落的功能基因、蛋白质及相关代谢途径的影响方面。然而,由于重金属污染与土壤微生物之间关系十分复杂,对其影响因素进行综合并定量化分析是明确重金属对土壤微生物生态特性的影响及相关机理的关键。另外,还需加强分子生物学新技术的应用,明确微生物种群对重金属胁迫的响应机制。重点开展重金属剂量及暴露时间对土壤微生物生态特征的影响研究,并在此基础上确定重金属对土壤微生物的毒害浓度临界值,针对不同的土壤类型和重金属种类建立相应的微生物评价指标体系,以期为评估土壤的重金属污染状况和治理修复提供理论依据。

Ecological characteristics of microbes are always recognized as indicators of pollution in soil ecosystem, since microbes are more susceptible to heavy metals （HMs） stress than plants and animals. This review summarized the recent advances in the effect of HMs on soil microbes. The aspects included changes of soil microbial biomass, community structure/function and diversity, metal resistance genes/proteins and metabolic ability, soil respiration and enzyme activity. Current studies gained controversial results with stimulative, negligible or inhibitive effects of HMs on soil microbes being observed. This may be owing to the complexity of soil microbial system, or the differences in species and concentrations of heavy metals, and soil properties. With the development of molecular biology, studies on the relationship between HMs and soil microbial characteristics were shifting from the macroscopic to microscopic level in recent years. In particular, many researches have revealed the impacts of HMs on the expression of functional genes and proteins of soil microbes, and the related metabolic pathways. However, due to the complex relationship between HMs and soil microbes, it is critical to quantify the role of different factors in impacts of HMs on microbial characteristics. Also, molecular mechanisms controlling the response of soil microbial community to heavy metal stress should be studied by new molecular biology techniques. Additionally, the toxicity threshold of HMs to soil microbes should be determined by exploring the effects of concentration and exposure time of HMs on soil microbes. An evaluation method based on soil microbial responses for different types of soil and HMs should be established as well. This will provide a rationale for assessing risk and remediation strategies of heavy metal contaminated soils.