Cellulase production from Bacillus spp. and purification with activated charcoal

Many bacteria have demonstrated the potentials of producing cellulases in copious amount. Bacteria of the genus Bacillus can utilize cheap lignocellulosic biomass to produce many bioproducts; like cellulases. One of the drawbacks in utilizing bacteria for the industrial production of cellulases is the high cost of recovering the enzyme from a submerged fermenting medium. This study seeks to produce cellulase from rice husk in a submerged fermentation. Species of Bacillus were isolated from cellulosic dumpsites, characterized and screened qualitatively for cellulase production on Carboxymethylcellulose (CMC) agar plates. The organisms were grown on mineral salt basal medium (NaNO₃- 2g, K₂HPO₄-1g, MgSO₄-0.5g, KCl-0.5g, CMC-2g, peptone-0.2g and agar- 8.5g), incubated at 40^oC. The optimum conditions for the production of cellulase was found to be 60^oC, at pH of 5.5 and substrate concentration of 1.0% (w/v). The crude enzyme was subjected to activated charcoal  purification and the cellulase showed a 2.5 (with B. megaterium) and 1.4-fold purification (with B. cereus) in one -step purification with (3% w/v) activated charcoal, at temperature of 50 ℃ and pH (6.0) and contact time (3hrs). The result of SDS-PAGE analysis of purified cellulase using silver staining techniques showed four major bands corresponding to molecular weights of 30, 42, 55 and 70 kDa. The use of Bacillus sp. in downstream processing of lignocellulosic biomass pretreatment and activated charcoal in cellulose purification offers a huge opportunity for cutting cost. This method of enzyme purification is inexpensive, rapid, and simple which could facilitate downstream processing of industrial enzymes.