Isolation, Screening, and Kinetic Optimization of Cellulase Complexes Sourced from Thermophilic Fungal Strains

International Journal of Chemistry | Vol. 4, No. 2, February 2013 | pp. 9–16

DOI: 10.46882/2013/IJC/000053

Article Type: Original Research Paper

Title: Isolation, Screening, and Kinetic Optimization of Cellulase Complexes Sourced from Thermophilic Fungal Strains

Names of Authors: C. N. Nwosu¹, H. A. Tanaka²*

Authors’ Affiliations:
¹Department of Biochemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Biotechnology, Tokyo Institute of Technology, Tokyo, Japan.

Abstract: Industrial saccharification of tough lignocellulosic biomass requires robust cellulolytic enzymes that can resist thermal denaturation under operational refinery configurations. This study focuses on the selective isolation, biochemical screening, and thermal kinetic optimization of high-yielding cellulolytic fungal strains sourced from geothermal hot spring soils. Soil suspensions underwent enrichment culturing in Mandels' mineral media containing microcrystalline cellulose at elevated temperatures. Two distinct fungal strains displaying large hydrolysis zones via Gram's iodine clearing tests were isolated. The highest-yielding strain was identified morphologically and via genetic sequencing as Aspergillus fumigatus. Optimization experiments under solid-state fermentation showed that maximum endoglucanase and exoglucanase production occurred at a temperature of 45°C and a medium pH of 5.0 after 96 hours of incubation. Utilizing agricultural cotton residues as alternative substrates induced a high enzyme yield (6.2 U/mL) compared to wood sawdust (2.1 U/mL). The crude cellulase complex retained over 85% of its initial catalytic activity across a temperature stability range of 40 to 60°C for 24 hours, establishing an exceptionally stable enzyme framework for economic bioethanol manufacturing tracks.

Keywords: Thermophilic fungi; Aspergillus fumigatus; Solid-state fermentation; Cellulase; Thermal stability; Bioethanol production

Manuscript Timeline: Received: July 11, 2012; Revised: August 20, 2012; Accepted: September 15, 2012; Published: February 06, 2013.

Citation: Nwosu, C. N., & Tanaka, H. A. (2013). Isolation, Screening, and Kinetic Optimization of Cellulase Complexes Sourced from Thermophilic Fungal Strains. International Journal of Chemistry, 4(2), 9–16.

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