A novel thermostable cellulase cocktail enhances lignocellulosic bioconversion and biorefining in a broad range of pH.

ABSTRACT

Lignocellulose is the most abundant biomass in nature, and the effective biorefining of them is dependent upon enzymes with high catalytic activity and stability in extreme pH and high temperatures. Due to the molecular constraints for a single enzyme, obtaining a more excellent active pH range can be more easily achievable through the simultaneous activity of two or more enzymes in a cocktail. To address this, we attempted to develop a cocktail of novel thermostable cellulases with high hydrolytic ability and stability. Two cellulases were mined, identified, cloned, and expressed from the camel rumen microbiota. The PersiCel1 demonstrated its maximum relative activity at the pH of 8, and the temperature of 60 °C and the PersiCel2 was optimally active at the pH of 5 and the temperature of 50 °C. Furthermore, utilization of the enzyme cocktail implies the synergistic relationship and significantly increased the saccharification yield of lignocellulosic substrates up to 71.7% for sugar-beet pulp (active pH range of 4-9) and 138.7% for rice-straw (active pH range of 5-8), compared to maximum hydrolysis of Persicel1 or PersiCel2 separately at 55 °C. Our results indicate the probable applicability of PersiCel1, PersiCel2, and their cocktail in numerous industries, specifically biorefineries and lignocellulose bioconversion based technologies.