SELECTIVE MICROBIAL PRODUCTION OF XYLITOL FROM BIOMASS BASED SUGAR STREAM WITH ENRICHED PENTOSE COMPONENT

摘要

The present invention utilizes yeast Candida tropicalis (NRRL 12968) for xylitol production, as an alternative and unexplored strain with high bioconversion rate and stability at higher initial xylose concentration. Different parameters are optimized for batch fermentation of xylose to xylitol such as initial xylose concentration, aeration (vvm), agitation (rpm), percent inoculum addition, and oxygen transfer rate. Maximum xylitol yield of 0.7 g/g of xylose is obtained with 3.33% inoculum, 250 g/l of initial xylose concentration, 0.2 vvm of aeration rate, and two stage agitation strategy comprising of 500 rpm for 0-24 hrs and 400 rpm for 24-72 hrs at not more than 72 hrs of fermentation time. The present invention coins a novel process mode of fermentation where the batch process is extended with continuous fermentation at optimum dilution rate of 0.02/hr with effective residence time of 52 hrs. Productivity of ‘batch followed by continuous’ process is 2.5 gm/lit/hr which is 1.34 times higher than batch and/or continuous process alone.

主权项

1. A process for microbial production of xylitol from xylose containing biomass comprising:
a) growing of yeast strain in a solid medium; b) inoculating the yeast strain obtained from step (a) in a seed medium containing seed fermentor; c) culturing the yeast strain from step (b) by transferring in production fermentor having xylose containing production medium; wherein fermentation of said xylose containing biomass is carried out with yeast strain capable of converting xylose to xylitol; and d) removing the yeast strain from said production medium and recycling it for continuous production of xylitol.