Optimization of Enzymatic Hydrolysis of Rice Straw for Bioethanol Production Using Crude Fungal Enzymes

International Journal of Chemistry | Vol. 3, No. 4, April 2012 | pp. 26–33

DOI: 10.46882/2012/IJC/000043

Article Type: Original Research Paper

Title: Optimization of Enzymatic Hydrolysis of Rice Straw for Bioethanol Production Using Crude Fungal Enzymes

Names of Authors: C. N. Nwosu¹, K. A. Boateng²*

Authors’ Affiliations:
¹Department of Biochemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.

Abstract: Converting lignocellulosic agricultural residues into fermentable reducing sugars requires highly active and stable cellulolytic enzyme complexes. This study focuses on the optimization of the enzymatic hydrolysis of alkali-pretreated rice straw using crude cellulase systems obtained from Aspergillus niger via solid-state fermentation. The rice straw was pretreated with 2.0 M NaOH at 80°C for 2 hours to remove lignin and increase surface accessibility. Enzymatic saccharification parameters, including enzyme loading, substrate concentration, incubation temperature, and saccharification period, were evaluated systematically. Maximum reducing sugar yield was achieved using an enzyme loading of 25 U/g of substrate and a 5% w/v substrate concentration at an operating temperature of 45°C and pH 5.0 after 72 hours. Under these optimized conditions, the glucose yield reached a peak concentration of 28.5 mg/g of dry substrate, representing a cellulose conversion efficiency of 74.2%. High-Performance Liquid Chromatography (HPLC) profiling of the hydrolysate confirmed that glucose and cellobiose were the primary monosaccharides produced. The low accumulation of fermentation inhibitors like furfural suggests that this optimized hydrolysate is highly suitable for downstream bioethanol fermentation processes.

Keywords: Rice straw; Fungal cellulase; Alkaline pretreatment; Enzymatic hydrolysis; Glucose yield; Bioethanol

Manuscript Timeline: Received: July 10, 2011; Revised: August 22, 2011; Accepted: September 14, 2011; Published: April 02, 2012.

Citation: Nwosu, C. N., & Boateng, K. A. (2012). Optimization of Enzymatic Hydrolysis of Rice Straw for Bioethanol Production Using Crude Fungal Enzymes. International Journal of Chemistry, 3(4), 26–33.

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