title: Characterization of cadmium-resistant bacteria and their potential for reducing accumulation of cadmium in rice grains.
abstract: Cadmium (Cd) pollution is a serious widespread environmental problem that not only destroys the microbial ecology of soil and decreases crop production, but also poses a serious risk to human health. Many methods have been used for the remediation of Cd pollution but none of these is totally satisfactory. Microbial remediation strategies have attracted increasing interest since they are environmentally friendly and cost-effective. In the present study, three Cd-resistant bacteria were isolated and evaluated for potential application in Cd bioremediation. Based on their morphological, physiological and biochemical characteristics, together with 16S rDNA gene sequence analyses, bacteria were identified as Stenotrophomonas acidaminiphila (2#), Pseudomonas aeruginosa (9#) and Delftia tsuruhatensis (12#). Pseudomonas aeruginosa showed very high tolerance to metals, especially Cd (2200mg/L), Zn (1800mg/L) and Pb (1200mg/L), and is thought to be a multi-metal-resistant bacterium. Pseudomonas aeruginosa was also sensitive to 13 different antibiotics. The effects of the bacterial strains on the growth of rice plants and their ability to reduce Cd accumulation from Cd-contaminated soils in pot experiments were also evaluated. For Oryza sativa L. A grown in contaminated soil (3mg/kg Cd), the accumulation of Cd was decreased by 31.2 and 25.5% in brown rice and polished rice, respectively, by strain 9#; Pseudomonas aeruginosa was more effective in reducing Cd accumulation in rice grains than a mixture of strains. For Oryza sativa L. B, a mixture of strains acting synergistically was more effective than a single strain in reducing Cd accumulation; treatment with mixed strains (strains+3mg/kg Cd) resulted in 41.3, 35.9, and 32.6% reductions in Cd accumulation in unhulled rice, brown rice and polished rice, respectively. Although different results were obtained for two rice varieties, it can still be concluded that Cd-resistant bacteria are suitable for reducing Cd accumulation in rice grains and show potential for bioremediation of Cd-contaminated soils.
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Lin
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China.
authors.forename: Renxiang
authors.initials: R
authors.lastname: Mou
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China.
authors.forename: Zhaoyun
authors.initials: Z
authors.lastname: Cao
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Wu
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China; Laboratory of Quality & Safety Risk Assessment for Rice (Hangzhou), Ministry of Agriculture, Hangzhou 310006, China. Electronic address: cmingxue@126.com.
authors.forename: Mingxue
authors.initials: M
authors.lastname: Chen
mesh_terms: D001673:Biodegradation, Environmental; D002104:Cadmium / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D042742:Delftia / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D002523:Edible Grain / Q000378:metabolism; D012275:Oryza / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D020588:Stenotrophomonas / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D002104:Cadmium
keywords: Bioremediation; Cadmium-resistant bacteria; Pseudomonas aeruginosa; Rice grains