Co-fermentation of acid treated coconut wastes using mixed Bacillus cultures for enhanced production of extracellular enzymes: Application in bioconversion of raw coconut fibers

Higher cost of production and functioning efficiency are the two most important aspects of cellulolytic enzymes, as they directly affect the bioconversion of cellulosic waste into fermentable sugars. Thus, the current study aims to investigate the production of cellulolytic enzymes from low-cost waste biomass for use in the sustainable hydrolysis of biomass to yield fermentable sugars. Since coconut waste is a major contributor to biodegradable waste, two different parts of coconut, including the hard shell of coconut (CS) and the fibers of the shell (FS), have been used for enzyme production as feedstock. Further, enzyme production has been carried out on co-fermentative and acid-pretreated coconut substrates (CS and FS) at different quantities using mixed bacterial cultures. Following this, a crude enzyme with a maximum 20 U/gds FPA, 62 U/gds BGL, and 167 U/gds EG has been produced by mixed Bacillus cultures under co-fermentation of 0.5% acid-pretreated CS and FS substrates at a quantity of 5:5 (g:g) at 35oC and pH 5.0. The crude enzyme showed its thermal stability for 16h at 50oC and released ~34g/L of sugars from the hydrolysis of untreated FS biomass in 24h. This work may have significant applications in the area of biomass-based biorefining as well as waste management.