Digestive Alkaline Proteases from the Goby (Zosterisessor ophiocephalus): Characterization and Potential Application as Detergent Additive and in the Deproteinization of Shrimp Wastes

Abstract

Alkaline proteases from the viscera of the goby (Zosterisessor ophiocephalus) were extracted and characterized. Proteolytic crude extract from goby viscera was active and stable in alkaline solution. The optimum pH and temperature were 10.0 and 50°C, respectively, using casein as a substrate. The crude alkaline protease was extremely stable in the pH range of 5.0–12.0. Zymography activity staining using casein as a substrate showed the presence of at least four distinct proteases.

The alkaline proteases showed extreme stability toward nonionic surfactants (Tween 80 and Triton X-100) and were relatively stable toward oxidizing agents, retaining more than 60% of their initial activity in the presence of 2% sodium perborate. Furthermore, the alkaline crude enzyme extract showed relative stability and compatibility with commercial liquid and solid detergents. Wash performance analysis revealed that goby crude extract could effectively remove a variety of stains, such as blood and chocolate. Further, alkaline proteases from goby viscera were found to be effective in the deproteinization of shrimp wastes. A high level of deproteinization 80.0% ± 1.5 was recorded with an enzyme/substrate ratio (E/S) of 20 U/mg. These results suggest that enzymatic deproteinization of the shrimp shell wastes, using Z. ophiocephalus proteases, could be applicable to the chitin production process.

Keywords:

• digestive proteases
• Zosterisessor ophiocephalus
• detergent additive
• shrimp wastes

Acknowledgments

This work was funded by the Ministry of Higher Education and Scientific Research-Tunisia.