Abstract:

Arsenic contamination in soil has become one of the global environmental problems due to extensive mining and industrial activities. As the first discovered arsenic hyperaccumulator in the world, Pteris vittata L. has been considered as an ideal plant for arsenic polluted soil remediation. The absorption and transport processes of arsenic in P. Vittata are regulated by many factors, among which the endophytic bacteria play a supportive role. However, the response mechanism of microorganisms to arsenic enrichment in P. Vittata has not been well studied. In order to explore the response mechanism of endophytic microorganisms in P. Vittata to arsenic pollution, the pot experiments with different arsenic concentrations (0 mg∙kg^-1, 250 mg∙kg^-1, 500 mg∙kg^-1) were carried out. The arsenic contents and microbial communities in the rhizosphere, roots and stems were analyzed and correlation analyses between arsenic pollution and the microbial community structures of rhizosphere and endophytic compartments in P. Vittata were performed. The results showed that the arsenic concentration in the stems of Pteris vittata L. was much higher than that in the roots. The translocation factors of arsenic in stems were 103.53 and 93.98, respectively, and the bioconcentration factor were 99.99 and 66.83, respectively, when the arsenic concentration in soils were 250 mg∙kg^-1 and 500 mg∙kg^-1. The results of microbial community diversity showed that arsenic stress had a significant effect on the microbial community structure (P=0.001), and the arsenic pollution had a greater effect on the microbial community structure in rhizosphere than on the endophytic microbial community structure. Different members of the order Rhizobia were identified as core microorganisms enriched in the rhizosphere and roots of P. Vittata. The correlation analyses results showed that Devosia and Rhizobacter were positively correlated with the arsenic content of the dominant microbial compositions (Pearson correlation coefficient>0.6). Moreover, Stenotrophomonas in the stems of P. Vittata was not only a core microorganism but also a dominant microorganism positively correlated with arsenic contents.

Key words: arsenic, Pteris vittata L., microbial community, core microbes, soil contamination, soil restoration

摘要：

由于广泛的采矿和工业活动,土壤砷污染已成为全球环境问题之一。蜈蚣草（Pteris vittata L.）作为世界上首次被发现的砷超累积植物,被认为是一种修复土壤砷污染的理想植物。蜈蚣草对砷的吸收和转运过程会受多种因素调控,其中蜈蚣草内生菌能够促进这一过程,然而目前关于微生物促进蜈蚣草砷富集的响应机制方面的研究报道还很少。为探明蜈蚣草内生微生物对砷污染的响应机制,采用不同砷添加量（0、250、500 mg∙kg^-1）进行蜈蚣草盆栽试验,结合蜈蚣草根际土、根和茎叶砷含量分析及对应微生物群落分析,研究砷污染对蜈蚣草根际及内生微生物群落结构的影响及相关性。结果表明,砷在蜈蚣草茎叶中的富集量远高于根内砷含量,当土壤砷污染水平分别为250 mg∙kg^-1和500 mg∙kg^-1时,蜈蚣草茎叶砷富集系数分别为99.99和66.83,转运系数分别为103.53和93.98。微生物群落多样性结果表明,砷胁迫对微生物群落结构具有显著影响（P=0.001）,砷污染对蜈蚣草根际土微生物群落结构的影响大于对内生微生物群落结构的影响,其中根瘤菌目是在蜈蚣草根际及根内富集的核心微生物。相关性分析结果表明,德沃斯氏菌属（Devosia）、根瘤杆菌属（Rhizobacter）等菌属是与砷含量呈正相关的优势微生物种群（P>0.6）。在蜈蚣草茎叶中,寡营养单胞细菌属（Stenotrophomonas）不仅是核心微生物,还是与砷含量呈正相关的优势微生物种群。

关键词: 砷, 蜈蚣草, 微生物群落, 核心微生物, 土壤污染, 土壤修复