Influence of inoculation of arsenic-resistant Staphylococcus arlettae on growth and arsenic uptake in Brassica juncea (L.) Czern. Var. R-46.

An arsenic hypertolerant bacterium was isolated from arsenic contaminated site of West Bengal, India. The bacteria was identified as Staphylococcus arlettae strain NBRIEAG-6, based on 16S rDNA analysis. S. arlettae was able to remove arsenic from liquid media and possesses arsC gene, gene responsible for arsenate reductase activity. The biochemical profiling of the isolated strain showed that it had the capacity of producing indole acetic acid (IAA), siderophores and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. Furthermore, an experiment was conducted to test the effect of S. arlettae inoculation on concurrent plant growth promotion and arsenic uptake in Indian mustard plant [Brassica juncea (L.) Czern. Var. R-46] when grown in arsenic spiked (5, 10 and 15 mg kg(-1)) soil. The microbial inoculation significantly (p<0.05) increased biomass, protein, chlorophyll and carotenoids contents in test plant. Moreover, as compared to the non-inoculated control, the As concentration in shoot and root of inoculated plants were increased from 3.73 to 34.16% and 87.35 to 99.93%, respectively. The experimental results show that the plant growth promoting bacteria NBRIEAG-6 has the ability to help B. juncea to accumulate As maximally in plant root, and therefore it can be accounted as a new bacteria for As phytostabilization.