Effects on the rice seedling growth by cadmium tolerant bacteria under cadmium stress

Cadmium, which possesses the character of lipid solubility, bioaccumulation and toxicity, is considered as the most hazardous heavy metal with abroad applications. Microorganism growing in cadmium-rich environment for a long time forms tolerance and resistance to cadmium.Adsorption and accumulation to heavy metal by cadmium tolerant bacteria are one of available measures to treat cadmium contamination. Two strains, named JL 1 and JL-2, with strong cadmium tolerance, were isolated from cadmium-contaminated soil in Zhangshi, Shenyang development zone, China. While the concentration of Cd²⁺ in liquid nutrient medium was 100mg/L, the two bacteria could survive and their absorption rates to Cadmium were 99.5% and 99.7%. In the experiment, the effects of JL-1 and JL-2 on the rice seedling growth under cadmium stress were investigated. The results showed that cadmium stress could severely inhibit the growth of rice seedling. With the increasing concentration of Cd²⁺ treatment, the amount of rice seedling growth, root activity, and chlorophyll content decreased significantly. However, after treatment of JL-1 and JL-2, the amount of rice seedling growth, root activity, and chlorophyll content increased strikingly. And JL-1 and JL-2 were further testified detoxification on rice seedling growth, which was under cadmium stress.