Isolation, Kinetic Optimization, and Characterization of Thermophilic Alkaline Lipases from Spent Bleaching Earth Soil

International Journal of Chemistry | Vol. 5, No. 10, October 2014 | pp. 73–80

DOI: 10.46882/2014/IJC/000073

Article Type: Original Research Paper

Title: Isolation, Kinetic Optimization, and Characterization of Thermophilic Alkaline Lipases from Spent Bleaching Earth Soil

Names of Authors: C. N. Nwosu¹, Y. S. Takahashi²*

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

Abstract: Industrial biocatalysis in detergent formulations and biodiesel production requires robust lipolytic enzymes that maintain activity under high temperatures and alkaline pH conditions. This study focuses on the isolation, kinetic optimization, and biochemical characterization of thermophilic alkaline lipases produced by a novel fungal strain sourced from oil refinery spent bleaching earth dumpsites. Soil suspensions underwent enrichment cultures in olive oil-infused media at 45°C. The highest-yielding isolate was identified via 18S rRNA gene sequencing as Aspergillus flavus strain SBE-L1. Solid-state fermentation parameters were optimized using response surface methodology. Maximum lipase activity (42.5 U/mL) was achieved at an incubation temperature of 45°C, an initial substrate pH of 8.5, and a fermentation period of 96 hours using palm kernel cake as a solid matrix. Characterization profiles showed that the crude enzyme complex retained over 85% of its initial catalytic activity across a temperature range of 40 to 60°C and a pH stability window of 7.5 to 9.5 for 12 hours. The enzyme exhibited high tolerance toward commercial anionic surfactants, proving its industrial viability for bio-detergent product lines.

Keywords: Alkaline lipase; Aspergillus flavus; Response surface methodology; Thermal stability; Surfactant tolerance; Biocatalysis

Manuscript Timeline: Received: February 18, 2014; Revised: March 25, 2014; Accepted: May 02, 2014; Published: October 05, 2014.

Citation: Nwosu, C. N., & Takahashi, Y. S. (2014). Isolation, Kinetic Optimization, and Characterization of Thermophilic Alkaline Lipases from Spent Bleaching Earth Soil. International Journal of Chemistry, 5(10), 73–80.

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