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A Thermostable Aluminum-Tolerant Protease Produced by Feather-Degrading Bacillus thuringiensis Isolated from Tea Plantation

[ Vol. 28 , Issue. 5 ]

Author(s):

Tianwen Wang*, Chen Liang, Sha Xiao, Li Li*, Hongju Xu, Yafei An, Mengyuan Zheng and Lu Liu   Pages 563 - 572 ( 10 )

Abstract:


Background: Proteases with keratinolytic activity are widely used in biotechnologies. The feather-degrading Bacillus thuringensis isolated from soil sample of a tea plantation produced high level of extracellular keratinase.

Objective: This study aimed to analyze the properties by biochemical and enzymological methods to gain information for better utilization of the enzyme.

Methods: The enzyme was purified with ion exchange and size exclusion chromatography. The substrate preference, optimal pH and temperature, and the effects of organic solvents and ions were checked. Circular dichroism was performed to compare the secondary structures of the native and apo-enzyme.

Results: The enzyme worked best at 50oC, and it was an acidic serine protease with an optimal pH of 6.2. Ions Ca2+ and Mg2+ were essential for its activity. Organic solvents and other metal ions generally deactivated the enzyme in a concentration-dependent manner. However, Mn2+ and DMSO, which were frequently reported as inhibitors of protease, could activate the enzyme at low concentration (0.01 to 2 mmol/L of Mn2+; DMSO <2%, v/v). The enzyme exhibited high resistance to Al3+, which might be explained by the soil properties of its host’s residence. Circular dichroism confirmed the contribution of ions to the structure and activity.

Conclusion: The enzyme was a thermostable aluminum-tolerant serine protease with unique biochemical properties.

Keywords:

Thermostability, serine protease, keratinase, Al3+ resistance, Mn2+ activation, organic activation, DMSO activation.

Affiliation:

College of Life Sciences, and Institute for Conservation and Utilization of Agro-Bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, Fujian Provincial University Engineering Research Center of Industrial Biocatalysis, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007, College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, College of International Education, Xinyang Normal University, Xinyang 464000



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