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ThesisItem Open Access Bioremediation and management of bacterial blight of rice with compatible consortia of arsenic degrading bacteria and plant growth promoting microbes(AAU, Jorhat, 2017) Talukdar, Kuldeep; Bora, L. C.Microorganisms influence the fate of heavy metals in the environment. Increasing anthropogenic and irrigation activities had escalated the risk of arsenic pollution in crop fields and this has added new thoughts for research workers to explore microbial transformation as a tactic to achieve arsenic bioremediation. Present study was made to exploit the potential of arsenic absorbing bacteria (AAB) and develop consortial formulation with plant growth promoting Pseudomonas fluorescens Pf-1 for bioremediation of arsenic and management of bacterial blight (BB) of rice in Assam. Out of six Bacilli bacteria isolated from arsenic contaminated soils of Assam, two Bacilli showing phylogenetic similarity with Paenibacillus sp. and Bacillus cereus had potential for arsenic bioremediation. The two Bacilli strains could tolerate 1000ppm of arsenic with 98.30 and 97.68 per cent absorption ability, respectively. Talc based consortial bioformulations were prepared using these arsenic absorbing microbes along with P. fluorescens Pf-1 and field evaluated for management of bacterial blight of rice along with arsenic bioremediation. Significantly highest reduction of bacterial blight severity (41.11%) and highest reduction of arsenic (17.56ppm) was recorded with the treatment comprising consortial formulation of Paenibacillus sp. and Pseudomonas fluorescens Pf-1. Population dynamics of the bioagents in different bioformulations were assayed upto 90 days for their compatibility assessment in sterilized and unsterilized soil conditions. Significantly higher population count of Paenibacillus sp., Bacillus cereus and P. fluorescens Pf-1 was recorded upto 90 days of soil inoculation in both sterilized and unsterilized soil depicting positive compatibility of the microbes in varied soil micro-environmental conditions. The consortial formulation of Paenibacillus sp. and Pseudomonas fluorescens Pf-1 also significantly enhanced yield of rice (24.67g/plant) as well as other yield attributing characters of rice plant. Enzymatic assay experiment tested the activity of glutaredoxin-dependent arsenate reductase (glutaredoxin 2 from E. coli), with NADPH/arsenate being the electron donor/acceptor. Compared to the control without protein extracts or glutaredoxin, arsenate reduction by E. coli glutaredoxin 2 was observed, with absorption decreasing at a rate of 0.0012 ABS/min.