In the present study, a potential bacterial strain with maximum urease activity was isolated from urea-rich paddy field soil for biocement production. The bacterial isolate was screened using Christensen selective agar media and named as KLUVAA. This isolate was found to be tolerant up to 10 % urea. 16S rRNA sequencing analysis identified the isolate KLUVAA as Bacillus cereus. Biocement production was carried out using tap water with 431.7 mg L-1 of hardness as a natural source of calcium. Functional groups present in biocement were analysed using FT-IR spectrum. The morphology and elemental composition of the biocement was studied using SEM with EDS mapping and XRD analyses. Thermogravimetric analysis was used to study the thermal stability of the microbial biocement. Further, process parameters were optimized for enhancing the yield of biocement.

Curdlan gum is a neutral water-insoluble bacterial exopolysaccharide composed primarily of linear β-(1,3) glycosidic linkages. Recently, there has been increasing interest in the applications of curdlan and its derivatives. Curdlan is found to inhibit tumors and its sulfated derivative possess anti-HIV activity. Curdlan is biodegradable, non-toxic towards human, environment and edible which makes it suitable as drug-delivery vehicles for sustained drug release. The increasing demand for the growing applications of curdlan requires an efficient high yield fermentation production process so as to satisfy the industrial needs. In this perspective, the present work is aimed to screen and isolate an efficient curdlan gum producing bacteria from rhizosphere of ground nut plant using aniline-blue agar. High yielding isolate was selected based on curdlan yield and identified as Bacillus cereus using gas-chromatography fatty acid methyl ester analysis. B. cereus PR3 curdlan gum was characterized using FT-IR spectroscopy, SEM, XRD and TGA. Fermentation time for curdlan production using B. cereus PR3 was optimized. Media constituents like carbon, nitrogen and mineral sources were screened using Plackett-Burman design. Subsequent statistical analysis revealed that Starch, NHNO, KHPO, NaSO, KHSO and CaCl were significant media constituents and these concentrations were optimized for enhancement of curdlan production up to 20.88 g/l.

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