Statistical optimization of rapid production of cellulases from Aspergillus niger MA1 and its application in bioethanol production from rice hulls

Abstract

The aim of this study was the utilization of rice hulls (RH) as a clean, cost effective, renewable and abundant agro-waste in bioethanol production by simple and applicable methods; for this purpose Aspergillus niger MA1 was isolated from RH and selected from many other isolates. This isolate produced 15.0, 3.38 and 49.1 U/g RH for CMCase, FPase and β-glucosidase, respectively, by solid state fermentation of RH after 36 h. The cellulases of the fungus showed good thermal and pH stability with maximum activity at 50°C and pH 5. An increase in cellulases productivity by statistical optimization and multi-response of SSF medium was revealed. Addition of 0.25% brej 35 to tap water or saline is very effective in elution of A. niger MA1. Cellulase which was successfully used in saccharification of steam explosion pretreated RH, revealed 16.36 g/L reducing sugars and subsequently fermentation by Saccharomyces cerevisiae which produced 9.42 g/L ethanol after 24 h.

Keywords: Rice hulls, bioethanol, cellulases, solid state fermentation, Aspergillus niger MA1, statistical optimization, multi-response

African Journal of Biotechnology, Vol 13(31) 3702-3714