强化龙葵富集镉根际促生菌的分离、筛选与鉴定

【背景】植物-微生物联合修复土壤重金属污染日渐兴起,获取与超富集植物高效互作的微生物是实现联合修复技术进步的关键。龙葵在镉农田污染修复中广泛应用。【目的】筛选可促进龙葵生长及富集镉的耐镉根际促生菌。【方法】从龙葵根际土分离耐镉菌株,筛选具有良好促生特性的菌株,水培试验考察镉胁迫下菌株对植物生长及镉富集能力的影响,确定可促进龙葵生长及富集镉的微生物菌株,通过生理生化特性和16S rRNA基因序列分析进行菌株的初步鉴定。【结果】分离得到NT1、AXY1、AW2和AW1四株强化龙葵富集镉促生菌,经鉴定分别为Lysinibacillus sp.、Beijerinckia fluminensis、Achromobacter animicus和Herbaspirillum huttiense。上述菌株均可有效促进龙葵生长,增加其株高和干物质积累,提高地上部镉富集量。其中,NT1可使株高、地上部干重分别增加31.33%和62.65%,AW2可使地上部镉富集量增加37.29%。【结论】筛选所得菌株可为提高植物修复效率提供实践依据,为研制田间施用生态功能菌剂做铺垫,用于农田镉污染的微生物-龙葵联合原位修复。

Isolation, screening and identification of plant growth promoting rhizobacteria to enrich cadmium accumulation in Solanum nigrum L.

Background] Plant-microbial remediation becomes prevailing in the remediation of soil heavy metal pollution. The key to achieve this is to obtain microorganisms which can interact with hyperaccumulator effectively. Solanum nigrum L. is widely used in the remediation of cadmium pollution of farmland. Objective] To screen cadmium tolerant plant growth promoting rhizobacteria (PGPR) which can promote the growth and cadmium accumulation of Solanum nigrum L. Methods] Cadmium tolerant strains with good growth promoting characteristics were isolated and screened from rhizosphere soil of Solanum nigrum L. The effects of cadmium stress on plant growth and cadmium accumulation ability were investigated under hydroponic culture, and microorganism which can promote growth and cadmium accumulation of Solanum nigrum L. was determined. The strain was identified by its physiological and biochemical characteristics and the analysis of its 16S rRNA gene sequence. Results] Four PGPR strains, NT1, AXY1, AW2 and AW1, were isolated from Solanum nigrum L., which were identified as Lysinibacillus sp., Beijerinckia fluminensis, Achromobacter animicus and Herbaspirillum huttiense. The growth of Solanum nigrum L., was enhanced by four strains, as the increase of height, dry matter accumulation and the cadmium accumulation of the aboveground part. Strain NT1 increased height by 31.33%, and increased the dry weight of the aboveground part by 62.65%. Strain AW2 increased the cadmium accumulation by 37.29%. Conclusion] Screening of strains can provide a practical basis when it comes to improving the efficiency of plant remediation. It can also help to prepare the ecologically functional bacteria and be used for the microorganism and Solanum nigrum L. combination in situ remediation in the cadmium polluted farmland.