Production of fermentable glucose from bioconversion of cellulose using efficient microbial cellulases produced from water hyacinth waste

Abstract

The economic production of cellulase enzymes for various industrial applications is one of the major research areas. A number of broad industrial applications, for example, in cellulosic biomass hydrolysis for simple sugars such as glucose and subsequent biofuel production, make these enzyme systems the third most demanding enzymes. Nevertheless, due to their production on commercial substrates, cellulases fall into the category of costly enzymes. Therefore, the goal of the present work is to evaluate the enhancement of cellulase production and its utilization in the enzymatic hydrolysis of biomass using low-cost cellulosic substrate, which is abundant and widely available. In this context, waste biomasses of water hyacinth (WH), including leaves and stems, have been used as feedstock to produce cellulases via solid-state fermentation (SSF) in the current study, which improves its production as well as activity. Furthermore, the impact of process parameters like temperature and pH has been investigated for improved cellulase production. At optimum concentration using 10 g of feedstock, 22 IU/gds of FP, 92 IU/gds of BGL, and 111 IU/gds of EG have been noticed in day 5 of SSF. Herein, 40 °C has been identified as the optimum temperature for cellulase production, whereas 50-55 °C has been recorded as the optimum reaction temperature for cellulase enzyme activity. Additionally, pH 5.5 has been identified as the optimum pH for cellulase enzyme production, whereas this enzyme was thermally stable (55 °C) at pH 5.0 up to 3.5 h. Further, the cellulosic biomass hydrolysis of WH leaves via an optimized crude enzyme has been performed, and this could release 24.34 g/L of glucose in 24 h of the reaction. The current findings may have potential for developing cellulases for mass-scale production using WH-based waste bioresources for numerous biorefinery applications.