NaCl-activated extracellular proteinase from Virgibacillus sp. SK37 isolated from fish sauce fermentation |
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Authors: | Sinsuwan S Rodtong S Yongsawatdigul J |
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Affiliation: | Authors Sinsuwan and Yongsawatdigul are with School of Food Technology, Suranaree Univ. of Technology, Nakhon Ratchasima 30000, Thailand. Author Rodtong is with School of Microbiology, Suranaree Univ. of Technology, Nakhon Ratchasima 30000, Thailand. Direct inquiries to author Yongsawatdigul (E-mail: ). |
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Abstract: | ABSTRACT: Virgibacillus sp. SK37 exhibited high extracellular proteolytic activity in skim milk broth containing 10% NaCl. Optimum conditions of the crude proteinase were at pH 8.0 and 65 °C. The proteinase was strongly inhibited by phenylmethanesulfonyl fluoride (PMSF) and preferably hydrolyzed Suc-Ala-Ala-Pro-Phe-AMC, suggesting the serine proteinase with a subtilisin-like characteristic. Proteolytic activity increased with NaCl concentration up to 20%. Ca2+ activated the enzyme activity but reduced enzyme stability at 65 °C. Several proteinases with dominant molecular mass (MW) of 81, 67, 63, 50, 38, and 18 kDa were detected on native-polyacrylamide gel electrophoresis (native-PAGE) activity staining in the absence and presence of 25% NaCl. These results demonstrated that Virgibacillus sp. SK37 produced salt-activated extracellular proteinases. Virgibacillus sp. SK37 could be a promising strain for starter culture development used in fish sauce fermentation. |
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Keywords: | bacterial proteinase fish sauce moderately halophilic bacterium NaCl-activated proteinase Virgibacillus sp |
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