Cellulose

The pentose sugar d-xylose is the predominant hemicellulosic compound, which comprises about one-third (25–35%) of the total carbohydrates present in the lignocellulosic biomass, which remains unutilized due to a lack of an optimized enzymatic method of xylose metabolism. Lignocellulose is renewable, and this low-cost carbohydrate is potentially attractive for producing useful chemicals (xylitol) and biofuel (bioethanol). The large-scale manufacturing of ethanol necessitates the efficient conversion of xylose from lignocellulosic feedstock. Thermostable organisms can be a potential source of thermostable enzymes for commercial and scientific interests. Therefore, T. thermophilus (a thermophile fungus) is explored as the alternative source of the thermostable enzyme xylose reductase. After heterologous expression in E. coli, purification of the native form of xylose reductase, which is thermostable, was done for the first time. Finally, the biochemical characterization of xylose reductase at different pH and temperature conditions was enumerated using various biophysical techniques. This study summarizes current information regarding yeast xylose reductases and the many ways used to provide an environmentally benign and long-term alternative source of XR for lignocellulose biomass consumption at higher temperatures in the fermentation sector. This study concludes that as far as its activity is concerned, xylose reductase works best around pH 7 and 45 °C. This information is very useful for industry as the temperature of fermenters containing heat-treated lignocellulose biomass is usually high and frequently affects the percentage yield of the final product.