抗耐镉、铬重金属菌株筛选及水稻根际土壤微生态效应研究

发布时间：2018-05-03 14:09

本文选题：水稻 + 重金属　；参考：《华中农业大学》2016年博士论文

【摘要】：本研究从镉、铬污染的水稻田土壤中筛选抗耐镉、铬的本土菌株,并研究这些菌株对水稻幼苗生长的影响,进一步研究其抗耐重金属机理,为其田间应用奠定基础。同时,通过对不同浓度的外源镉、铬胁迫下水稻根际微生物群落构成、微生物群落功能多样性研究与分析,获得土壤微生态差异的信息,为微生物修复重金属污染提供理论依据。主要研究结果如下:(1)采用梯度浓度驯化方法,从重金属镉、铬污染的稻田土壤中分离、筛选出8株高抗耐铬、镉真菌菌株。5株抗耐镉浓度高达16 mmol/L的菌株,4株抗耐铬浓度高达1000 mg/L的菌株,其中菌株X29抗耐镉浓度为16 mmol/L,抗耐铬浓度为1000 mg/L。经形态观察和分子鉴定,确定了这8株菌株的种属地位分别为:绿僵菌(Metarhizium anisopliae),拟茎点霉(Phomopsis sp.),曲霉(Aspergillus sp.),木霉(Trichoderma sp.),尖孢镰刀菌(Fusarium oxysporum),酿酒酵母(Saccharomyces cerevisiae),青霉(Penicillium sp.);其中菌株52和菌株55都为青霉,其余6株分别属于不同菌株。(2)将获得的8株抗耐重金属菌株与苗龄为5d的水稻植株同时置于1/2MS培养基上共培养,7d后统计水稻生物学性状,从中筛选出菌株3(Metarhizium anisopliae)和菌株39(Saccharomyces cerevisiae)2株对水稻生长无抑制作用的菌株。菌株39进行其抗耐镉、铬机理研究,利用扫描电子显微镜(SEM)观察菌株39铬、镉处理后菌丝损伤,进而菌体出现凋亡;傅里叶变换红外光谱(FTIR)发现菌株39吸附铬、镉离子后,FTIR图谱中的C=O,C-H和N-H吸收峰有明显的变化,表明镉离子的吸附都与酰胺和羧基等基团有密切关系。(3)不同浓度重金属镉和铬处理水稻,水稻根际土壤细菌DGGE图谱中有部分一致的条带,这表明水稻根际土壤微生物具有相似的细菌群落。主成分1为57.24%,主成分2为27.98%,主成分分析结果表明水稻根际微生物群落随重金属处理时间的延长变化较大。DGGE特异性条带被切割、测序,构建系统发育树表明,获得的菌株主要是酸杆菌(Acidobacteria)18.75%,黏球菌(Myxococcales)12.50%,芽单胞菌(Gemmatimonas)12.50%,硫发菌(Thiothrix)9.38%。抽穗期水稻根际芽单胞菌属(Gemmatimonas)的相对丰度与镉浓度成正比,而披毛菌(Gallionellaceae)的相对丰富度与铬浓度成正比。在水稻成熟期,绿硫细菌(Chlorobiales)的相对丰度随镉浓度增加而增加。结果表明不同重金属在不同时期对土壤微生物影响是不同的。(4)利用高通量测序技术分析不同浓度不同重金属处理水稻根际土壤微生物,发现丰度比大于0.3%细菌种属有46个,其中铬处理的占31个,镉处理的占28个。土壤含镉20mg/kg时水稻根际土壤细菌相对丰度,细菌群落多样性和碳利用的多样性表现最高。在对照土样中长绳菌属(Longilinea)相对丰度比重金属处理的都高。在Cd2和Cd3处理中,假单胞菌(Pseudomonas)相对丰度比其他重金属处理和对照都高。抽穗期细菌相对丰度和碳源利用能力高于成熟期。因此,一定浓度重金属能够改进微生物群落结构和碳源利用。从重金属污染的水稻田筛选到的抗耐重金属菌株,为重金属污染微生物修复提供了菌株。根据外源镉、铬胁迫对水稻根际微生物群落结构、种群组成的影响,为利用微生态平衡理论指导重金属污染的稻田微生物修复提供理论依据。
[Abstract]:The effects of these strains on the growth of rice seedlings were studied . The results were as follows : ( 1 ) The results were as follows : ( 1 ) The results were as follows : ( 1 ) The results were as follows : ( 1 ) The results were as follows : ( 1 ) The results were as follows : ( 1 ) The results were as follows : ( 1 ) The results were as follows : ( 1 ) The strain X29 had a concentration of 16 mmol / L and a concentration of 1000 mg / L . The strains were identified by morphological observation and molecular identification . The results showed that the relative abundance of Cd and C - H and N - H in the rhizosphere soil of rice were significantly different . The results showed that the relative abundance of Cd ions was 57.24 % , the main component 2 was 27.98 % . The results showed that the relative abundance of cadmium ions increased with the increase of Cd concentration . ( 4 ) In the treatment of Cd ~ ( 2 + ) and Cd ~ ( 3 ) , the relative abundance of bacteria in rhizosphere soil of rice was higher than that of other heavy metals .

【学位授予单位】：华中农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X172;S511;S154.3

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