Bioethanol potentials of corn cob hydrolysed using cellulases of Aspergillus niger and Penicillium decumbens

Abstract

Corn cob is a major component of agricultural and domestic waste in many parts of the world. It is composed mainly of cellulose which can be converted to energy in form of bioethanol as an efficient and effective means of waste management. Production of cellulolytic enzymes were induced in the fungi Aspergillus niger and Penicillium decumbens by growing them in mineral salt medium containing alkali pre-treated and untreated corn cobs. The cellulases were characterized and partially purified. Alkali pre-treated corn cobs were hydrolysed with the partially purified cellulases and the product of hydrolysis was fermented using the yeast saccharomyces cerevisae to ethanol. Cellulases of A. niger produced higher endoglucanase and exoglucanase activity (0.1698 IU ml-1 and 0.0461 FPU ml-1) compared to that produced by P. decumbens (0.1111 IU ml-1 and 0.153 FPU ml-1). Alkali pre-treated corn cob hydrolysed by cellulases of A. niger yielded 7.63 mg ml-1 sugar which produced 2.67 % (v/v) ethanol on fermentation. Ethanol yield of the hydrolysates of corn cob by cellulases of P. decumbens was much lower at 0.56 % (v/v). Alkali pre-treated corn cob, hydrolysed with cellulases of A. niger is established as suitable feedstock for bioethanol production.