Growth stimulatory effect of Ochrobactrum intermedium and Bacillus cereus on Vigna radiata plants

Abstract

Aims: This study assessed the plant growth-promoting ability of the bacterial strains Ochrobactrum intermedium (isolate CrT-1) and Bacillus cereus (isolate S-6). Methods and Results: Two chromium resistant bacterial strains isolated from chromium-contaminated wastewater and soils were identified as O. intermedium CrT-1 and B. cereus S-6. These strains were inoculated on seeds of mungbean Vigna radiata var NM-92, which were germinated and grown under chromate salts (300 μg ml-1 of CrCl3or K2CrO 4). The data show that Cr(VI) was more toxic because of its better availability to plants roots when compared with Cr(III). The major part of Cr(VI) supplied to the seedlings was reduced to Cr(III) in the rhizosphere by the bacterial strains, thus lowering the toxicity of chromium to seedlings. Conclusions: Strains have significant Cr(VI) resistance and reduction potential and have ability to enhance mungbean plant growth under chromium stress. Significance and Impact of the study: These strains could be utilized for the growth of economically important cash crops as well as for the bioremediation of chromium-polluted soils. © 2006 The Authors.