Bioconversion of fruit peels to levan by solid state fermentation and statistical optimization by response surface methodology

Levan is a naturally occurring polysaccharide, found in many microorganisms and plants. The polymer is composed of fructose molecules. Food processing industries generate a lot of sugar rich waste consisting of different fruit peels that could be used for levan biosynthesis of levan. The present research presents levan production by Bacillus subtillis via solid state fermentation (SSF) using various sucrose-rich fruit peels. Peels of mango, banana, apple, and sugarcane bagasse were screened and maximum levan yield (1.87 mg/g) was found with mango peels after 24 h at pH 7 and 30 °C. Levan production from mango peel was further optimized for physical parameters using central composite design (CCD) of response surface methodology (RSM). The maximum levan yield (7.586 mg/g) from mango peels was achieved at 120 h incubation, 60% moisture content, 7 pH, and 32 °C. The functional groups of levan were confirmed by FTIR analysis. Sugar content was done by HPLC analysis, which confirmed levan has only fructose sugar. Mango peel could be a potential source for levan production.