Optimization of suitable carbon source for polysaccharide production by Lactobacillus sp. UTMC ۳۹۸۳

BACKGROUND AND OBJECTIVESCurrently, exopolysaccharide is one of the most important used biopolymers. So, newly isolated strains with the ability to produce more exopolysaccharide such as Limosilactobacillus have become attractive fields of industrial microbiology research. The aim of this study was to propose different sources of carbon and examining different concentrations of these sources, to find the optimal carbon source.MATERIALS AND METHODSIn this study, the lactic acid strain of Lactobacillus sp. UTMC ۳۹۸۳ was used. Bacteria were inoculated on the Erlenmeyer flask containing the MRS broth culture (۳۷oC, ۱۰۰ rpm for ۲۴hours). Then, ۱۰% of the volume of seeding flasks was replaced with other carbon sources (including lactose, whey, molasses, glucose syrup, and sucrose) in Erlenmeyer flasks containing production based on MRS broth and polysaccharide production, residual substrate and bacterial biomass are measured.RESULT AND DISCUSSIONBy examining the addition of ۲.۵% to ۶۰% concentrations of sucrose to the culture medium and examining the amount of changes in exopolysaccharide production, the highest production rate was ۶۷ g/liter at a concentration of ۳۰%. By replacing the concentrations of (۲۰-۲۵-۳۰-۳۵-۴۰)% whey as a carbon source, the amount of exopolysaccharide production in the highest concentration of whey (۴۰%) was ۱۲ g/liter. Also, by replacing the concentrations of (۳۰-۴۰-۵۰-۶۰)% lactose and molasses with concentrations of (۲۰-۳۰-۴۰)% the amount of exopolysaccharide production was reported zero. By replacing the concentrations of (۱۰-۲۰-۳۰-۴۰) % of the glucose syrup, the average amount of exopolysaccharide production with the highest concentration (۴۰%) was detected as ۲۴.۴ g/liter.CONCLUSIONThe results of this study showed that the bacteria were unable to use lactose sugar, whey and molasses. By examining glucose syrup as a carbon source, it was also determined that this carbon source is only suitable for the bacteria revival, although exopolysaccharide production in this medium was weak. Finally, the medium with ۳۰% sucrose (approximately ۶۷ g/L) was found to be the most suitable carbon source for the growth and production of exopolysaccharide.

کلیدواژه ها:

Optimization ، Exopolysaccharide ، Lactic acid bacteria ، Limosilactobacillus