Isolation and Identification of Cadmium-Resistant Bacteria and Their Influence on Growth of Cadmium-Stressed Rice Seedlings

Abstract

Aim: Isolating and screening of the cadmium-resistant bacteria (Cd-r-BA) that were benefited to rice cultivation. Methods: The Cd-r-BA was isolated from rice rhizospheric soil. The adsorption and removal rate of cadmium when the Cd-r-BA grows in cadmium-containing broth was detected by the flame atomic absorption spectrometric method. The effects of Cd-r-BA to cadmium-stressed rice seedlings were detected by using water culture method. The identification of the object bacterium was depended on its 16 S rRNA gene sequence. Results: The results showed that four Cd-r-BA strains of Cdr-1~Cdr-4 were screened out. Especially, when the strain Cdr-2 grows in broth containing 400 mg/L of cadmium, the adsorption and removal rate of 61.27% cadmium was detected. The growth of the rice seedlings was prompted by the strain Cdr-2 under cadmium-free rice culture nutrients in water culture box, while the toxic effects of the cadmium to the rice seedlings was enhanced by the strain Cdr-2 under 10 mg/L of cadmium condition. The strain Cdr-2 was identified as species Klebsiella aerogenes by 16 S rRNA gene sequencing. Conclusion: The conclusion was drawn that a Klebsiella aerogenes strain Cdr-2 that characterized by cadmium-resistance and growth-promoting was isolated and screened from rice rhizosphericsoil. Significance: The results could provide reference data for the application of strain Cdr-2 to the rice cultivation.