Fed-batch sorbitol to sorbose fermentation by A. suboxydans

Abstract

Batch kinetics for sorbitol to sorbose bioconversion was studied at 20% sorbitol concentration. The culture featured 90% conversion of sorbitol to sorbose in 20 hours. Increasing the initial substrate concentration in the bioreactor decreased the culture speci®c growth rate. At 40% initial sorbitol concentration no culture growth was observed. The batch kinetics and substrate inhibition studies were used to develop the Mathematical Model of the system. The model parameters were identi®ed using the original batch kinetic data (S o 20%). The developed mathematical model was adopted to fed-batch cultivation with the exponential nutrient feeding. The fed-batch model was simulated and implemented experimentally. No substrate inhibition was observed in the fed-batch mode and it provided an overall productivity of 12.6 g/l-h. The fed-batch model suitably described the experimentally observed results. The model is ready for further optimization studies.

Metabolic Engineering of Microorganisms for Vitamin C Production

“…Control of initial concentration of sorbitol with 200 g/L, the production and yield of L-sorbose were 200 g/L and 14.2 g/L/h (Giridhar and Srivastava 2002 ) . Besides this, with constant speed feeding of 600 g/L D-sorbitol, the concentration of L-sorbose was 1.6 times greater than batch fermentation; whereas 272.37 g/L L-sorbose achieved with linear feeding strategy (Giridhar and Srivastava 2001 ) ; exponential feeding of 700 g/L D-sorbitol after 10 h batch fermentation with 200 g/L D-sorbitol made 290 g/L L-sorbose (Srivastava and Lasrado 1998 ) . When L-sorbose was further converted to 2-KLG, huge amount of L-sorbose will make the bacteria metabolize abnormally, meanwhile the production and yield reduced.…”

Mathematical modelling and its use for design of feeding strategies for L‐Sorbose fermentation

“…Several researchers have attempted to increase the sorbose productivity by implementing different feeding strategies in fed-batch fermentation (Bosjnak et al, 1991;Srivastava and Lasrado, 1998). Bosjnak et al (1991) attempted gradient fed-batch fermentation and obtained a sorbose concentration and productivity of 372 g/L and 11.62 g/L,h respectively.…”

“…Bosjnak et al (1991) attempted gradient fed-batch fermentation and obtained a sorbose concentration and productivity of 372 g/L and 11.62 g/L,h respectively. Srivastava and Lasrado, 1998 cultivated Acetobacter suboxydans in fed-batch fermentation by feeding nutrients containing sorbitol exponentially and obtained a sorbose concentration and productivity of 290 g/L and 12.6 g/L,h. In the present investigation the fed-batch demonstrated a productivity of 15.5 g/L.h which is the highest compared to above literature reported values.…”

“…Some attempts were made in the past to eliminate sorbitol inhibition and to improve reactor productivity by some fed-batch fermentations (Bosjnak et al, 1991;Mori et al, 1981;Srivastava and Lasrado, 1998). Trial and error procedure for substrate feeding has been adopted for these fed-batch fermentations.…”

Fed-batch cultivation of Acetobacter suboxydans for the microbial oxidation of D-sorbitol to L-sorbose

“…Several researchers have attempted to increase the sorbose productivity by implementing different feeding strategies in fed-batch fermentation [5,7,9]. Bosjnak et al [5] attempted gradient fed-batch fermentation and obtained a sorbose productivity of 11.62 g l )1 h )1 .…”