Exopolysaccharides (EPS) the high molecular weight microbial substances play an important role in enhancing soil aggregation as well as maintaining water holding capacity around the rhizosphere. Therefore, looking into the fact that rice is one of the important food crops for most of the people of the world and the ability of EPS to increase the uptake of nutrients by plants and protect from drought stress. The present investigation was carried out to study the EPS production by bacteria isolated from rice cultivar Naveen with four treatments viz., aerobic (−5 kPa), saturation (0 kPa), submerged (2 cm standing water) and control (without any water treatment) and their interaction with soil labile carbon pools. Soil (0–15 cm depth) was collected from panicle initiation stage of the crop growth to isolate EPS producing bacteria. Different parameters like microbial biomass carbon (MBC), readily mineralizable carbon (RMC) and organic carbon (OC) alongwith total and colloidal EPS were estimated. The total and colloidal EPS increased 26.0% and 9.0% among the treatments over saturation. The MBC, RMC and OC were found to increase 30.0%, 19.0% and 4.0% among the treatment over saturation. These findings indicated a positive correlation between carbon pools and total and colloidal EPS production. Similarly, in this study, 22 EPS producing bacteria were isolated from the rice rhizospheric region and amongst 4 isolates were found to tolerate maximum level of water stress (−0.73 MPa). Further, optimization studies indicated that all these 4 bacterial isolates produced EPS at 37 °C, 80 mM salt concentration and pH value 7.5 within 3 days of incubation. Further, among different carbon sources, sucrose followed by glucose was found to be best for production of EPS. Further work is going on to evaluate the efficacy of these potential EPS producing bacterial isolates under field conditions.

外多糖（EPS）是高分子量微生物物质，在增强土壤聚集以及保持根际周围的持水能力方面发挥着重要作用。因此，考虑到水稻是世界上大多数人的重要粮食作物之一，并且EPS具有增加植物吸收养分并抵抗干旱的能力。进行本研究是为了研究从水稻品种Naveen分离出的细菌产生的EPS的产生，包括有氧（-5 kPa），饱和（0 kPa），淹没（2 cm静水）和对照（无水）四种处理处理）及其与土壤不稳定碳库的相互作用。从作物生长的穗开始阶段收集土壤（深度为0–15 cm），以分离产生EPS的细菌。估算了不同的参数，例如微生物生物量碳（MBC），易矿化碳（RMC）和有机碳（OC）以及总和胶体EPS。在饱和状态下，总和胶体EPS分别增长26.0％和9.0％。发现在饱和状态下，MBC，RMC和OC分别增加30.0％，19.0％和4.0％。这些发现表明碳库与总和胶态EPS产量之间呈正相关。同样，在这项研究中，从水稻根际区域分离出22种产生EPS的细菌，发现其中4种菌株可耐受最大水平的水分胁迫（-0.73 MPa）。此外，优化研究表明，所有这4种细菌分离株在孵育3天之内均在37°C，80 mM盐浓度和pH值7.5时产生EPS。进一步，在不同的碳源中，发现蔗糖和葡萄糖最适合生产EPS。进一步的工作正在进行中，以评估在田间条件下这些潜在的EPS产生细菌分离物的功效。