Statistical optimization of lignocellulosic waste containing culture medium for enhanced production of cellulase by Bacillus tequilensis G9

Abstract

The ever increasing energy demands of modern civilization and rapidly dwindling fossil fuels point towards a renewable substitute like biofuels. However, higher costs associated with biofuel productions is the major bottleneck for its commercialization. The present study demonstrates the use of a statistical approach called response surface methodology (RSM) to investigate the optimum parameters for maximum production of cellulase by Bacillus tequilensis G9. The Plackett–Burman design (PB) of the RSM analysis indicated grass straw (GS) concentration, pH, FeSO4, inoculum, MgSO4, incubation period and NH4Cl as significant variables that influence the cellulase production. Further, to propose the best medium for the maximum production of cellulase by B. tequilensis G9, the most influential parameters, namely concentrations of GS as substrate, FeSO4, pH, inoculum size, etc. were fine-tuned by central composite design (CCD) involving four factors and five levels. The CCD analysis demonstrated 8% substrate concentration, 1.5% of inoculum along with 10 ppm FeSO4 and a pH of 5.5 in media as optimum conditions for highest enzyme production. The field emission scanning electron microscopic analysis of the treated GS showed structural alterations depicting significant deconstruction caused by B. tequilensis G9. The yield of the partially purified cellulase proteins were found to be 21% revealing molecular mass between 30 and 97 kDa. The enhanced cellulase production by B. tequilensis G9 demonstrated in our study brands its applications in many industrial processes like biorefinery, biofuels, etc.