Biodegradation of textile dye Direct Blue 71 using root nodulating Rhizobium sp.

532-539Textile dye pollution  is an issue of environmental concern. . Though microbes have been widely explored for their dye degrading abilities, little work has been reported using root nodulating bacteria. In the present study, an attempt has been made to use a non-pathogenic, nitrogen fixing soil bacteria for biodegradation of textile dye, Direct Blue 71 (DB71). The 11 isolates of Rhizobium showed potential to decolourize the triazo dye DB71. Of these, isolate TUR2 (GenBank accession no. JF820124) showed the highest (95%) ability to decolourize the dye. Over expression of oxidative and reductive enzymes in the presence of the dye indicated their role in degradation which was confirmed using analytical techniques like HPLC, FTIR and GC-MS. Phytotoxicity studies have shown these dye metabolites to be non-toxic. Results of this study indicate potential use of Rhizobium sp. in biodegradation of textile dye, and suggest further investigation towards developing a dual technology of biofertilization coupled with bioremediation

Differential expression of antioxidant enzymes under arsenic stress in Enterobacter sp.

Arsenic is a major contaminating heavy metal due to its frequent occurrence and toxicity. Out of different remediation approaches, bioremediation using bacteria has been extensively studied. In this study, 29 bacterial isolates were screened for their arsenic tolerance capacity. One of the isolate, MUM2 showed maximum arsenic tolerance (10mM). Antioxidant enzymes were assayed in this isolate under arsenic stress. Although, the CAT activity was found to increase significantly, the SOD activity showed a significant decrease under 9mM arsenic stress. The results obtained suggest a possible role of CAT in combating arsenic stress. Further studies at genetic level would help in developing highly tolerant strains for remediation of arsenic