Biopolymer curdlan production from rhizospheric bacteria Priestia aryabhattai BMS3 from Vigna radiata (mung bean)

Curdlan, a microbial polysaccharide with unique gelling properties, has garnered significant attention with widespread importance in the food, pharmaceutical, and biomedical industries. This study presents the first report on Priestia aryabhattai as a curdlan-producing bacterium isolated from the rhizosphere of Vigna radiata (mung bean) plants. A variety of carbon and nitrogen sources were screened where sucrose and diammonium hydrogen phosphate respectively yielded the best results. Process optimization using Taguchi method resulted in a significant 3.57-fold increase in curdlan yield, from 0.14 to 0.5 g/L. The optimal fermentation medium consisted of inoculum percentage (10%), (NH₄)₂HPO₄ concentration (0.8%), KH₂PO₄ concentration (0.3%), and sucrose concentration (10%) along with trace elements at a pH 7.0. Techniques such as nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were utilized to characterize the extracted curdlan to confirm its structural and morphological properties. Some defining features of curdlan like the β-1,3-linkage were visualized through FTIR as the absorption band at 890 cm⁻¹ and sharp, irregular fragmented structures as observed through SEM analysis. These findings highlight P. aryabhattai BMS3 as a novel curdlan producer and demonstrate an optimized approach for improving curdlan production efficiency.