反枝苋内生菌筛选及其铬富集效果研究

Screening of Plant Growth-promoting Endophytic Bacteria from Amaranthus retroflexus L. and Their Effects on Chromium Accumulation in Plant

以分泌吲哚乙酸(IAA)、铁载体能力以及对重金属离子耐受性为筛选指标,从反枝苋(Amaranthus retroflexus L.)根系中筛选出分泌IAA、铁载体和耐铬能力强的两株菌株G3和G8,通过盆栽实验研究分析了其对反枝苋累积铬的影响,根据形态特性和16S r DNA序列分析对供试菌株进行分类鉴定。结果显示,菌株G8分泌IAA能力达到17.80 mg·L-1,强于其他菌株;菌株G3、G8对铬、镉、铅离子的耐受性分别为200、20、300和100、20、400 mg·L-1。盆栽实验中,接种菌株G8处理后反枝苋地下部生物量和重金属累积量与对照相比显著提高,并增强了地下部对铬的富集能力。通过进行16S r DNA序列分析,菌株G3与Pseudomonas sp.CZGSD7的序列相似性达到99%;菌株G8与Pseudomonas extremorientalis CNU082017的序列相似性达到100%,2株菌株初步鉴定为假单胞菌属(Pseudomonas)。

The study isolated the chromium-resistant plant growth-promoting bacteria（PGPB） that producing indole-3-acetic acid （ IAA）, sid- erophores from Amaranthus retroflexus L. Two enhanced chromium（Cr）-resistant strains, named as G3 and G8, were isolated from the root which both have abilities to producing IAA and siderophores. According to tl-e morphological characteristics and 16 s rDNA,Pot experiments were conducted to investigate their effects on promoting the growth and Cr accumulation in A. retroflexus L. The result showed that strains G8 utilized tryptophan as a precursor for IAA synthesis was 17.80 mg · L^-1 and IAA production capacity was better than rest of other strains. The minimal inhibitory concentration of chromium, cadmium, lead for the strains G3 and G8 were 200, 20, 300 and 100, 20, 400 mg· L^-1 , respectively. The root （ up to 71.3 % ） biomass and accumulation of heavy metal increased significantly （ P 〈 0.05 ） after inoculation with strain G8 compared to the uninoeulated control. In addition, the strain G8 significantly increased the Cr concentration in the root of A. retroflexua L. The endophytic bacterial strain G3 and G8 were identified as Pseudomonas sp. （99 % similarity） and P. extremorientalis （100 % similarity） respectively,based on the 16S rDNA gene sequence analysis.