四川汉源万顺铅锌矿区蜈蚣草共附生细菌群落结构对重金属的响应特征

Response of symbiotic or epiphytic bacteria in Pteris vittata to heavy metals in a Pb-Zn mining area in Wanshun village,Hanyuan county,Sichuan Province

为了充分挖掘重金属污染地区植物共附生细菌资源,提高重金属污染土壤生态修复的效率,利用变性梯度凝胶电泳(Denaturing Gradient Gel Electrophoresis,DGGE)技术,对四川省汉源县万顺铅锌矿区蜈蚣草根状茎中共附生细菌多样性和群落结构进行了研究,并分析了共附生细菌群落结构与蜈蚣草根状茎中有效重金属间的关系.结果表明,不同采样点间的蜈蚣草共附生细菌多样性存在明显差异,多样性指数和丰富度指数均表现为尾矿>矿口>弃渣区>选矿区>农田.基于DGGE回收条带序列的系统发育显示,蜈蚣草共附生细菌包括芽孢杆菌属(Bacillus)、伯克氏菌属(Burkholderia)、根瘤菌属(Rhizobium)、假单胞菌属(Pseudomonas)、肠杆菌属(Enterobacteria)和弯曲杆菌属(Campylobacter)等细菌类群.相关性分析表明,共附生细菌多样性指数和丰富度指数均与有效Cu、Cd、Pb、Zn和As含量呈显著正相关(p<0.05).冗余分析(Redundancy Analysis,RDA)显示,有效As是影响蜈蚣草共附生细菌群落结构的关键因子,对砷含量较高的采样点,砷对蜈蚣草共附生细菌群落有促进作用,在砷含量相对较低的采样点,共附生细菌群落与砷呈负相关.研究表明,蜈蚣草存在丰富的共附生细菌种群,这些种群受蜈蚣草中有效重金属含量的影响明显,在修复重金属特别是砷污染土壤方面表现出潜在应用价值.

In order to explore the plant symbiotic or epiphytic bacteria resources from the heavy metal contaminated area and provide the theoretical guidelines for improving the ecological remediation efficiency, the diversity of the symbiotic or epiphytic bacteria in Pteris vittata rootstock collected from the Pb-Zn mining area in Hanyuan county, Sichuan Province, was investigated with the denaturing gradient gel electrophoresis （DGGE） method. The interrelationships between the symbiotic or epipbytic bacteria in community and the available heavy metal content in P. vittata rootstock were also analyzed： Our results showed that the diversity of symbiotic or epiphytic bacteria varied with the sampling sites. The diversity index, richness and evenness of the symbiotic or epiphytie bacteria community were in the order of railings〉ore-drawing-hole〉excavation waste dump〉ore dressing area〉agricuhural fields. The phylogenic analysis result based on the sequences of retrieved DGGE bands shows that Bacillus, Burkholderia, Rhizobium, Pseudomonas, Enterobacteria and Campylobacter were the dominant bacteria in P. vittata. Correlation analysis results show that the symbiotic or epiphytic bacterial diversity index and richness were significantly positive correlation with available Cu, Cd, Pb, and As（p〈0.05）. Redundancy analysis（RDA） results show that the available arsenic （As） was the key factor in shaping the symbiotic or epiphytic bacteria communities in P. vittata, and available arsenic had a positive effect on symbiotic or epiphytie bacteria with high As content, while the symbiotic or epiphytic bacterial communities were negatively correlated with As with low As content. Overall, our results show that abundant symbiotic or epiphytic bacteria existed in P. vittata, and these bacteria were obviously affected by the available heavy metal contents in P. vittata and possessed a application potential in remediating soil contaminated by heavy metals, especially As.