Exploring ethyl methane sulphonate induced, L-cysteine HCl resistant Bacillus subtilis putative mutant and its immobilization for enhanced acetoin synthesis.

Acetoin is a natural compound and is widely used in various industries such as food, dairy, cosmetics, paint, and pharmaceutical industry. The study aimed to enhance acetoin production through Bacillus subtilis by employing strain selection, mutagenesis, nutritional evaluation, and utilization of cell immobilization for enhanced acetoin production. A strain coded as SFS-13 was isolated from agricultural soil and identified as B. subtilis SFS-13. The acetoin production and glucose-consuming efficiency by wild-type SFS-13 were 8.62 ± 0.04 g/L and 25.33 ± 0.02%, respectively. After chemical mutagenesis of SFS-13 with ethyl methyl sulphonate, 99 putative mutant survivors were picked through the shake flask fermentation selection procedure. The culture conditions and evaluation of medium components were performed by varying one factor at a time. The highest production of acetoin was achieved by the use of beads with a diameter of 3 mm and a quantity of 250, 5 beads per mL, that gave a yield of 0.457 ± 0.01 g/g glucose. Also, the effect of temperature and pH on the production of acetoin was tested, and the most significant yield was found at 37℃ and pH 6, with 45.03 ± 0.11% GCE. The findings provide a structural foundation for the potential industrial-scale production of acetoin and other metabolites, which is relevant in sustainable biotechnological use in the food, pharmaceutical and cosmetic sectors.