微生物菌剂对镉污染土壤的修复及其生态效应

发布时间：2018-02-04 07:49

  本文关键词： 土壤 镉污染 响应面优化 微生物修复 生态效应　出处：《湖南农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着工业化发展和人们生活水平的提高,镉污染事件频繁发生,并引起广泛关注。微生物修复是一种成本低廉、环境友好且易于操作的修复方式,在治理土壤镉污染方面具有很大的应用潜力。通过分离筛选具有去镉性能的微生物,不仅能够丰富功能微生物的菌种资源库,还可以推动重金属污染土壤的植物—微生物联合修复技术发展。本研究从重金属污染土壤中分离筛选到多株耐镉真菌,选择去镉能力较强的菌株PC-8作为供试菌株,在单因素试验基础上采用响应面试验法优化了该菌株的去镉发酵条件,并将该菌制成菌剂,通过盆栽试验研究其对土壤镉污染修复的可行性及生态效应。主要研究结果如下：(1)从株洲清水塘工业区的重金属土壤中分离筛选到耐镉真菌9株,经过复筛、液体发酵试验以及传代稳定性试验,获得1株对镉去除能力最强,且遗传稳定的菌株PC-8。结合形态学观察和ITS序列分析,将菌株PC-8鉴定为新月弯孢霉(Curvularia lunata)。(2)通过单因素试验和响应面设计优化,得到菌株PC-8发酵最佳工艺条件为：初始pH 5.0、培养温度32℃、初始Cd2+浓度10 mmol/L。在此条件下,菌株PC-8的去镉率可达99.67%。(3)采用改进BCR提取法分析土壤中镉的化学形态,以电感耦合等离子体发射光谱法为测定方法,通过盆栽试验研究了土壤中总镉的含量变化和镉的形态变化。结果表明,施加菌剂降低了土壤中总镉含量,促进了残渣态镉向可交换态和氧化态镉转化,有利于提高土壤中镉的生物有效性。(4)采用盆栽试验,研究了菌剂和外源镉对黑麦草地上、地下部分生物量以及对镉富集的影响。结果表明,在10mg/kg外源镉、3%菌剂处理下,黑麦草的生物量最优,其根长、地上鲜重、地下鲜重分别是对照的1.16、2.66、1.49倍；在菌剂添加量及外源镉的处理下,黑麦草对镉的富集系数在0.253～0.335之间。(5)盆栽条件下,采用平板计数法定量研究了土壤中细菌、真菌、放线菌数量的变化规律。结果表明,菌剂对土壤中的微生物数量和种群结构有影响：菌剂加入土壤后,土壤微生物数量需要经过20～40d才能达到峰值；低菌剂添加量的影响较小,高菌剂添加量的影响较大。
[Abstract]:With the development of industrialization and the improvement of people's living standard, cadmium pollution has occurred frequently and caused widespread concern. Microbial remediation is a low-cost, environmentally friendly and easy to operate remediation method. It has great application potential in controlling soil cadmium pollution. Through isolation and screening of microorganisms with cadmium removal capability, it can not only enrich the microbial resource bank of functional microorganisms. It can also promote the development of phytoremediation technology for heavy metal contaminated soils. In this study, cadmium tolerant fungi were isolated and screened from heavy metal contaminated soils. The cadmium removal strain PC-8 was selected as the tested strain. On the basis of the single factor test, the cadmium removal fermentation conditions of the strain were optimized by response surface test, and the bacteria were made into fungicides. Pot experiments were conducted to study the feasibility and ecological effects of cadmium remediation on soil. The main results were as follows: 1) 9 cadmium tolerant fungi were isolated from heavy metal soils in Zhuzhou Qingshui Reservoir Industrial Zone. After screening, liquid fermentation test and passage stability test, a strain PC-8 with the strongest cadmium removal ability and genetic stability was obtained. Combined with morphological observation and ITS sequence analysis. The strain PC-8 was identified as Curvularia lunata.2) by single factor test and response surface design optimization. The optimum fermentation conditions of PC-8 were as follows: initial pH 5.0, culture temperature 32 鈩，

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