Alkaline proteases from a newly isolated Micromonospora chaiyaphumensis S103: Characterization and application as a detergent additive and for chitin extraction from shrimp shell waste

The present study was undertaken to characterize the extracellular thermostable serine alkaline proteases from newly actinomycete strain Micromonospora chaiyaphumensis S103 and to describe their evaluation in commercial detergents and shrimp waste deproteinization. This proteolytic crude extract was active and stable in alkaline solution. It was extremely stable in the pH range of 5.0-12.0. The optimum pH and temperature were 8.0 and 70 °C, respectively, using casein as a substrate. The thermoactivity and thermostability of proteases were enhanced by the addition of 5 mM Ca2+. Proteases from S103 were also used for shrimp wastes deproteinization in the process of chitin preparation. The percent of protein removal after 3 h hydrolysis at 45 °C with an enzyme/substrate ratio of 20 U/mg had reached 93%. Furthermore, S103 crude enzyme was stable towards several organic solvents and retained 100% of its original activity after 90 days of incubation in the presence of methanol, hexane, acetone, and DMSO. These properties make S103 proteases an ideal choice for application in detergent formulations, chitin production, and enzymatic peptide synthesis.