Year : 2020  |  Volume : 19  |  Issue : 4  |  Page : 338-349

Enhanced production, partial purification, and characterization of alkaline thermophilic protease from the endophytic fungus Aspergillus ochraceus BT21

1 Department of Chemistry of Natural and Microbial Products, National Research Center, Dokki, Giza, Egypt
2 Department of Molecular Biology, National Research Center, Dokki, Giza, Egypt

Correspondence Address:
PhD Eman W Elgammal
Assistant Professor, Chemistry of Natural and Microbial Products Department, National Research Centre (ID: 6014618), 12311 Dokki, Giza
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/epj.epj_31_20

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Backgroundand objective Endophytic fungi are thought to be a potential source for biologically active compounds such as enzymes, especially proteases which find their application in modern biochemical industries. The aim of this study was to optimize the production conditions of protease from Aspergillus ochraceus BT21, which was previously isolated from the Egyptian medicinal plant Ruprechita salicifolia. The produced protease was optimized, partially purified and characterized. Materials and methods A. ochraceus BT21 was identified by 18 S rRNA under the accession number of MN564896 in gene bank. The physicochemical parameters of the fermentation medium were optimized. Furthermore, the harvested protease was concentrated and partially purified by ethanol fractionation and then characterized to detect the enzyme identity. Results and conclusion The protease production increased by about 7.5-fold (3644.9 U/mg) after applying the final optimized fermentation medium, which contains dextrin 30, peptone 2, K2HPO4 1, MgSO4 0.5, KCl 0.5, and FeSO4 0.01(g/l) at 35°C, pH 8.0 and 150 rpm using 6% inoculum size after 6 days of incubation. The purification results showed that the highly recovered fraction was at 60% ethanol concentration with a purification fold of 4.3 and enzyme recovery of 36.5%. The enzyme was thermotolerant with an optimum temperature of 50°C and optimum pH of 8.0. Furthermore, it was observed that there was a reverse relationship between the metal ion concentration and the enzyme relative activity. Finally, the data indicated that casein and human blood were the most suitable substrates for this enzyme, indicating that the enzyme can work in alkaline conditions and has thermotolerance properties with high affinity toward the blood substrate, which makes it a potential candidate for detergent formulation to facilitate blood stain removal.

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