Effect Of Cd Contamination On Soil Microbial Community Structure In Flue-Cured Tobacco Rhizosphere

Soil microorganisms play an important role in rhizosphere soil ecosystems. The bacteria and fungi community structure of flue-cured tobacco rhizosphere by adding different content of Cd (2, 4, 8 and 16 mg.kg(-1)) were studied based on the PCR-DGGE analysis. The results were as follows:(1) The bacteria bands of Cd at 4 mg.kg(-1) level 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 (16mg.kg(-1)). The sequencing results showed 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 8 mg.kg(-1). Sequencing results showed 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 appeared at Cd concentration of more than 8 mg.kg(-1), which showed its addiction to higher Cd concentration.