Optimization of Xylose Reductase production from Citrobacter sp.

Abstract

Xylitol is a poly-hydroxy straight-chain five-carbon alcohol that can replace sugar in daily uses without any side effects. Lowered risk of dental carries and bone demineralization further support its involvement in a healthy lifestyle. In addition, its role in the synthesis of various commercial products like glycol, ethanol, and resins etc. increases its market value and makes it one of the most valuable bio-products. Microbial fermentation is a cost-effective and eco-friendly method for xylitol production from agricultural residues as available xylose is reduced to xylitol by Xylose reductase (XR) using an equivalent amount of NADPH as a mediator for electron transfer. Previous literature emphasized the use of fungi and yeast for xylitol production rather than bacteria. In contrast to available reports, the potential of the bacterial isolate was evaluated for xylitol production. The effect of process parameters was observed on xylitol yield in terms of XR activity. Out of sixty-eight bacterial isolates obtained, XYLBV-05 was selected for XR production after screening and was identified as Citrobacter sp. based on morphological, microscopic, and biochemical characteristics. Parametric analysis increased the XR production by 4.12 folds (36.61 U/ml). Preliminary results also proved its efficiency in conversion of biomass hydrolysate to xylitol at lab scale but further efforts are needed for xylitol production using agro-industrial lignocellulosic biomass at a large scale which will not only aid in the generation of revenue as a result of value-added products but will also help in environment conservation.