High-temperature tolerant enzyme based extraction of lignocellulose derived C5 and C6 sugars for the integrated production of a promising supplement for a diesel/jet-engine fuel

Abstract

Development of a novel, integrated production of C8 ester butyl butyrate (BuB), a promising supplement for diesel/jet-engine fuels, from lignocellulose derived C5 and C6 sugars is attempted by means of smart and innovative process design. In the pathway, enzymatic hydrolysis of biomass with high solid loading is an important step which requires reduced amount of water supply and energy input. However, increased substrate loading lead to diffusion limitations of enzymes, on top of nonproductive absorption of enzymes. Addition of ß-glucosidase over cellulase is another reason to increase the cost of enzymes. Viscozyme can be considered as a troubleshooter in these cases where it can offset high substrate loading and increased monomeric sugar generation. In the present study, 17.61 g/L of glucose, along with 7.43 g/L of xylose, have been recovered with a viscozyme concentration of 54.4 g/L. Additionally, thermal deactivation of viscozyme has been investigated. The deactivation constant is found to be gradually increasing with escalated enzyme loading from 24.2 g/L to 54.4 g/L. In this study, it has been found that hydrolysis of biomass follows a first order pseudo-kinetics and the same is eventually used to determine the fractal kinetics of cellulose hydrolysis. Fractal kinetics showed that increment of enzyme concentration is associated with lower fractal dimensions and increased binding capacity of substrate and enzyme. Diffusion limitation of the present enzyme-substrate system has also been investigated. It is observed that faster diffusion, along with increased resistances, can be achieved with increased enzyme concentration.