镉污染对烤烟根际土壤细菌和真菌群落结构的影响

Effect of Cd Contamination on Soil Bacteria and Fungi Community Structure in Flue-cured Tobacco Rhizosphere

根际土壤微生物是根际土壤生态系统的重要组成部分,为了明确镉污染条件下烤烟根际土壤微生物群落结构变化,采用全生育期盆栽方法,利用分子生物学PCR-DGGE技术,对不同浓度镉污染下烤烟根际细菌和真菌的群落结构进行了分析,结果表明:(1)镉污染浓度为4 mg kg-1处理的根际土壤细菌群落条带数,明显少于其他处理;随镉污染浓度的增加,一些土壤细菌类群逐渐消失,但特定细菌对高浓度镉污染具有较强的耐受能力;根际细菌可归入8个类群,Bacterium ellin、Acidobacteria酸杆菌和Mycobacterium分枝杆菌属对不同浓度镉污染具有较强的适应能力,其中leptolyngbya瘦鞘丝藻属能适应中等浓度的镉污染,在该浓度下,该微生物可大量繁殖为优势种群。(2)随着镉污染浓度增加,部分特有真菌类群出现,但是在中等镉浓度(4 mg kg-1)处理下,部分真菌类群消失;真菌群落结构可归入4个类群,其中优势和共有类群为Fusarium镰刀菌属和未知菌属,对不同浓度镉污染耐受性较强;Acremonium sclerotigenum硬化支顶孢霉对镉污染反应敏感,Rhizopus根霉菌属嗜好高浓度镉的真菌。

Soil microorganisms play an important role in rhizospheric soil ecosystems. To explore the effect of Cd contamination on soil microbial community structure in flue-cured tobacco rhizosphere, pot experiments were conducted with different treatment levels of Cd. The bacteria and fungi community structure in rhizosphere were examined using the PCR-DGGE fingerprinting with universal bacteria and fungi primers. The results were as follows:(1) The bacteria bands of Cd at 4 mg kg-1level were significantly less than other treatments. Some bacteria disappeared with the Cd concentration increasing. Some special bacteria had a stronger restoration capability at higher Cd contamination level. The sequencing results showed that the bacteria community was divided into 8 clusters. The Bacterium ellin, Acidobacteria bacterium ellin and Mycobacterium had strong resistance and adaptability to Cd contamination of different concentration. The Leptolyngbya had strong adaptability to Cd contamination of moderate concentration, which could become dominant population at this level.(2) The fungi community diversity in rhizosphere with different concentration of Cd had a significant difference compared with the bacteria. Some fungi appeared with the increase of Cd concentration, but some fungi disappeared at the moderate level of 4 mg kg-1. Sequencing results showed that the fungi community was divided into 4 clusters. The Fusarium and unknown species were the dominant fungi community, which existed in all treatments and had strong adaptability to different Cd concentration. The Acremonium sclerotigenum was sensitive to Cd contamination, but the Rhizopus had a preference to higher Cd concentration.