Biotechnological production of xylitol - A review on recombinant expression and its challenges

Abstract

       Xylitol, a natural polyol sugar is a promising bioproduct with Industrial applications in many sectors like sweeteners, health care products, oral care and as an excipient in pharmaceutical manufacturing. The xylitol market is expected to be 1.37 Billion USD by 2025 with a CAGR of 7.33 % between 2019 to 2024. The Industrial scale production of xylitol using lignocelluloses biomass hydrolysates involves catalytic reduction with Nickel catalyst under high pressure and temperature. However the yield of xylitol is around 60 % from xylose sugar, it requires extreme process conditions and subsequent processing steps which adds up to the cost of the product. Microbial fermentative production of xylitol with native yeasts, proves to be an efficient industrial process with the highest yield achievable around 3 g/l of xylitol from D- xylose. The major challenges in Industrial scale fermentative production of xylose is the need for optimized process and xylose utilization pathway engineered in recombinant hosts. This review focuses on the recombinant production and metabolic pathway engineering approaches adopted to achieve higher xylitol yields in yeasts.