Applications of fungal cellulases in biofuel production: Advances and limitations

Nonrenewable fossil fuels and their serious environmental impact have forced to develop renewable & sustainable energy sources. In this scenario, cellulases have found extensive applications in the biofuel industries. Three main components of the cellulase enzymatic system, namely endoglucanase, exoglucanase and β-glycosidase, effectively convert cellulosic substrates into fermentable sugars. The commercial production of cellulase is currently performed under submerged fermentation (SmF) conditions using mesophilic microbial strains which are non-economic and also non-sustainable. Although, production of fungal cellulases using solid-state fermentation (SSF) is economically advantageous and a preferable route for industrial purposes, it suffers from a few bottlenecks (e.g. scale-up, difficult to control process parameters). Therefore, the present review provides an overview of the cost-effective and present scenario of cellulase production in the biofuel industries including recent advancements. In addition, the current limitations hampering the cost-effective production of cellulase have also been discussed to resolve them in the near future.