Statistical optimization of cellulase production by halophilic strains isolated from Tunisian Sebkhas using the renewable marine biomass waste, Posidonia oceanica, as a cellulosic substrate

Abstract

Bio-based ethanol production from enzymatic lignocellulosic biomass degradation serves an efficient technology to combat the problem of depleting fossil fuels. High cost of the enzyme is the major obstacle in preventing the commercialization of this process. Thus, main objective of the present study was to optimize composition of culture parameters for enhancing cellulase production by two halophilic strains Oceanobacillus picture E50 and Bacillus vallismortis J77 using Posidonia oceanica waste (POW) as a substrate. A Plackett-Burman design was conducted to study and evaluate the weight of eight cultural variables on bacterial cellulase production. The optimal culture conditions for maximum enzyme yield were developed by maintaining the variables of POW concentration, NaCl concentration, POW liquor, bacterial strain and inoculum size at their higher levels, while keeping substrate particle size, glucose concentration and incubation time at their lower levels. The highest cellulase production in terms of CMCase activity was 950 U/L following this optimization process. Thus, the results obtained in this study demonstrated the potential of utilizing POW as a substrate for enhanced cellulase production by halophilic bacteria. B. vallismortis J77 produced the highest cellulase activity and therefore could be of great interest for saccharification of Posidonia oceanica biomass for biofuel and biorefinery applications.