Research Projects

Arsenic (As) contamination in agricultural soil is a critical concern throughout the globe contaminating rice, the most used crop in the world. Soil microbes are intricate role players in soil As dynamics, biogeochemistry, and plant As accumulation, and a detailed study is needed to propose a sustainable As remediation method involving agronomic practices and microbial interventions. According to the UN-SDG, and Central Pollution Control Board (CPCB)-Govt of India, As remediation from the agricultural fields for the greater health issues, is being promoted. This project aims to decipher new mechanisms of arsenic resistance and mitigation in microbes getting influenced due to extracellular polymeric substances (EPS) secretion, a novel and eco-friendly idea to promote sustainable agriculture in India. EPS are known for the production of microbial biofilms containing variable content of lipids, proteins, carbohydrates, and other biomolecules. Only a few studies are available to show the relation between EPS and As redox, transformation triggering the ars operon without any known mechanisms. Efflux and intracellular biotransformation of As via ars, aio, arr and arx operon activities will be checked in the presence of EPS overexpressing epsA, C, D, F, G, L, M, N, O, spo0A, and spo0H genes. The study targets to increase the natural As resistance capacity in microbes which might result in enhanced chelation of As to the EPS. Rice field soils will be analyzed for metagenomics and high throughput sequencing to identify the best bacterial species for further studies. A detailed compositional analysis of EPS using HR-MS and NMR will be needed before and after the gene over-expression. Speciation of As will be assessed using HPLC coupled ICP-MS which will point out the specific adsorption of As to the EPS. A live cellular EPS activity while adsorbing As at the surface will be monitored using nano-SIMS. The rhizospheric soil associated with the rice plants fluctuates in terms of As geochemistry and irrigation methods which influence soil microbial community. This soil-plant geochemical analysis will be critically assessed here. Another benefit of EPS application includes nutrient accumulation in the surrounding soil system promoting the plant’s growth which will be closely monitored. The applicability of EPS-producing microbes in the rice field is feasible or not, will be studied by maintaining different sets of soil microcosm systems. Rice seedlings will be maintained to check the root exudate secretion, and its effect on bacterial EPS production and As mitigation. The effects of root exudate on bacterial EPS production are a novel aspect that can help identify the mechanism of triggered bacterial EPS under variable environmental setups. This project promotes EPS producing bioagent development, mitigating As stress from soil to plant and increasing rice growth, and safe for the application in the agricultural soils to satisfy the UN-SDG 2030.