Cadmium (Cd) is one of the commonly found heavy metal contaminants in soil and has a toxic effect on plants and humans. Understanding the Cd resistance of soil microorganisms under different fertilization regimes can provide a theoretical basis for controlling heavy metal pollution by organic fertilizers. In order to investigate the effects of inorganic and organic fertilizers on the Cd resistance level of soil microorganisms, paddy soil samples were taken in Changzhou, Shanggao, and Fuzhou. A functional gene array (GeoChip 5.0) was used to investigate the distribution of microbial Cd resistance genes. The results indicated that the content of available Cd in soil with organic fertilizer[(1.08±0.70) mg·kg-1] was significantly lower than that in soils with inorganic fertilizer[(3.75±1.22) mg·kg-1](P<0.05). A total of 639 Cd resistance genes were detected. The abundance of microbial Cd resistance gene in soil with organic fertilizer was higher than that of inorganic soil. The content of available Cd, moisture content, pH, and ammonium nitrogen were important environmental factors affecting the distribution of Cd resistant microorganisms. Analysis of the molecular ecological network of Cd resistant microorganisms showed that pH, moisture content, and the effective state of the Cd content were the main factors affecting the potential interaction of functional microorganisms with inorganic fertilizer, and the main factors were total potassium and moisture content with organic fertilizer. Compared with inorganic fertilizers, the application of organic fertilizers can improve the Cd resistance level of microorganisms in soil and promote positive relationships among Cd resistant soil microorganisms.
Keywords: cadmium; cadmium resistance; functional genes; inorganic fertilizer; organic fertilizer.