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

Elgammal, Eman W.; El-Khonezy, Mohamed I.; Ahmed, Eman F.; Abd-Elaziz, Ahmed M.

doi:10.4103/epj.epj_31_20

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

Authors

Abstract

Background and 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 BT21, which was previously isolated from the Egyptian medicinal plant The produced protease was optimized, partially purified and characterized.
Materials and methods

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, KHPO 1, MgSO 0.5, KCl 0.5, and FeSO 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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