Isolation, Structural Profiling, and Optimizing Kinetics of Amylolytic Complexes Sourced from Thermophilic Aspergillus Strains

International Journal of Chemistry | Vol. 7, No. 6, June 2016 | pp. 41–48

DOI: 10.46882/2016/IJC/000093

Article Type: Original Research Paper

Title: Isolation, Structural Profiling, and Optimizing Kinetics of Amylolytic Complexes Sourced from Thermophilic Aspergillus Strains

Names of Authors: C. N. Nwosu¹, H. M. Sato²*

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

Abstract: The industrial saccharification of starch into simple glucose syrups requires robust amylolytic enzymes that can resist thermal denaturation during high-temperature steam liquefaction loops. This study details the isolation, microstructural profiling, and kinetic optimization of high-yielding alpha-amylase complexes produced by a thermophilic fungal strain sourced from processing soil surrounding artisanal cassava processing mills. Enrichment culturing was executed in starch-infused Mandels' media at 50°C, isolating a dominant strain identified via internal transcribed spacer (ITS) rRNA gene sequencing as Aspergillus fumigatus strain Cassava-A1. Response surface methodology optimized solid-state fermentation yields using wheat bran matrices. Maximum alpha-amylase activity (54.5 U/mL) was achieved at an incubation temperature of 50°C, an initial substrate pH of 6.0, and a fermentation period of 96 hours. Biochemical characterization showed that the crude enzyme complex retained over 85% of its initial catalytic activity across a temperature range of 45 to 65°C and a pH stability window of 5.5 to 7.0 for 24 hours. The high thermal stability of this enzyme system, along with its independence from calcium ions, makes it a viable candidate for bio-refinery industrial operations.

Keywords: Alpha-amylase; Aspergillus fumigatus; Solid-state fermentation; Thermal stability; Kinetic optimization; Starch saccharification

Manuscript Timeline: Received: November 10, 2015; Revised: December 18, 2015; Accepted: January 14, 2016; Published: June 03, 2016.

Citation: Nwosu, C. N., & Sato, H. M. (2016). Isolation, Structural Profiling, and Optimizing Kinetics of Amylolytic Complexes Sourced from Thermophilic Aspergillus Strains. International Journal of Chemistry, 7(6), 41–48.

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