Cellulase Activity of Aspergillus niger in the Biodegradation of Rice Husk

Abstract

Rice husk, a major waste product of rice milling factory in Nigeria, was hydrolyzed by cellulolytic enzymes of Aspergillus niger. Aspergillus niger synthesizes cellulase which biodegrade the cellulose content of rice husk. The cellulase activity was measured by the release of reducing sugar over the period of biodegradation. The reducing sugar content of the biodegraded rice husk showed a significant increase with an increase in days of biodegradation (0.560 -1.020mg/ml from day zero through day five, to day nine). The maximum yield of glucose concentration was observed on day five of biodegradation at pH of 5.4, while the minimum yield of glucose concentration was observed on day nine of biodegradation at pH 6.18. The study revealed that the growth of Aspergillus niger on rice husk increases its usefulness and that rice husk can through microbial degradation be converted to fermentable sugars and other useful product like alcohol. It also highlights the industrial potential of rice husks as possible substrates for cellulase enzyme production by Aspergillus niger which can eliminate agro-waste environmental pollution in Nigeria.