L-Sorbose Production by Gluconobacter oxydans using Submerged Fermentation in a Bench Scale Fermenter

Background and objective: L-Sorbose, as a precursor of ascorbic acid, can be biologically produced using Gluconobacter oxydans. The aim of this study was to optimize production of L-Sorbose by controlling concentration of the substrates and starter cultures. Material and methods: In this study, effects of three various fermentation parameters on the concentration of L-sorbose were assessed using fermenter (28°C, 1.4 vvm) and response surface methodology. These parameters included quantities of D-sorbitol (120-180 g lDw-1) (Deionized water) and yeast extract (6-18 g lDw-1) and inoculum/substrate ratios (5-10%). Results and conclusion: Results showed that the fitted model with high values of R2 (0.9594) and R2-adjusted (0.9228) could effectively predict the concentration of L-sorbose within the highlighted ranges for the variables. Furthermore, results demonstrated that the maximum concentration of L-sorbose was achieved at 42.26 g lDW-1 using D-sorbitol, yeast extract and inoculum/substrate ratio values of 153.42 g lDW-1, 12.64 g lDW-1 and 9.88%, respectively. These results have revealed appropriately of response surface methodology for the prediction of L-sorbose product quantity and optimization of the variables in this aerobic fermentation process.