Soil microbe interaction and its impact on selenium uptake by allium species

Abstract

The doctoral thesis aimed at examining the following objectives: 1.Characterization of seleniferous soils and isolation o f selenium tolerant bacteria 2.Determination of uptake of soil selenium by Allium species with rhizospheric bacteria 3.Examine the anti-oxidant and related properties in plants grown in seleniferous soils The salient findings of the study include characterization of seleniferous soils of Punjab and quantification of total selenium in soil and crop produce using instrumental neutron activation analysis (INAA) in collaboration with Radiochemistry Division, BARC, Mumbai. The observations indicated that the concentration of selenium in food grains is highest ever recorded. Further studies were carried out to isolate and characterize selenium tolerant bacteria which were identified as Bacillus sp (EU 622629; EU622630); Bacillus pumillus (EU 532490); and Bacillus cereus (EU 573774), with an aim to introduce these Se tolerant strains in removal of Se from selenium rich soils. The role of these bacteria was tested in facilitating the removal of Se in presence and absence of plants (Allium cepa). The findings confirm the positive role of Se tolerant bacteria in reducing the uptake of selenium by the plants vis-à-vis promoting the overall growth of the plant. The reduced form of selenium by these bacteria was also characterized and reported be the nano-structures in nature, opening avenues for research and application of these particles. Selenium accumulation is known to instigate pro-oxidant activity which further induces anti-oxidant protection, to counter Se toxicity. The present study also indicated the expression of both these activities at different levels of Se exposure, thus demonstrating the tolerance profile and biochemical activity induced by selenium oxyanions in Allium cepa. newline