Recent trends in hyperthermophilic enzymes production and future perspectives for biofuel industry: A critical review

Among different industrial applications of lignocellulosic biomass, biofuel production is receiving increasing attention. Many factors influence the transformation of lignocellulosic biomass into biofuels such as biomass composition, moisture content, and the desired final energy product. However, the presence of lignin and the need for de-polymerization of cellulose and hemicellulose into reducing sugars play a crucial role in the efficiency of biomass conversion. Among different methods, conversion of lignocellulosic biomass to fermentable sugars by enzymatic hydrolysis offers the potential for higher yield, lower energy consumption, higher selectivity and eco-friendly process. In that regard, the stability of hyperthermophilic enzymes at extreme temperatures acquired them a unique potential for the conversion of lignocellulosic biomass. In recent years, many trials were done to enhance the biological production and stability of thermostable enzymes. In addition to optimization of growth conditions and using chemical methods, many new genetic systems were developed. However, there is a gap in literature concerning the novel techniques used to enhance the production of hyperthermophilic enzymes and sustainability in biofuel industrialization. Therefore, the present review aimed to shed light on the recent trends used to enhance the production and stability of hyperthermophilic enzymes focusing on genetic engineering as an efficient and promising technique for cost-effective production. In addition, the impact of hyperthermophilic enzymes on biomass refinery and future biofuel industry was discussed. The present article highlighted the future positive impacts of hyperthermophilic enzymes on the biofuel production and the need of more research in this fascinating and boundless field. (C) 2019 Elsevier Ltd. All rights reserved.