Evidence of Cell-Associated Proteinases from Virgibacillus sp. SK33 Isolated from Fish Sauce Fermentation
Article first published online: 14 MAR 2011
© 2011 Institute of Food Technologists®
Journal of Food Science
Volume 76, Issue 3, pages C413–C419, April 2011
How to Cite
Sinsuwan, S., Rodtong, S. and Yongsawatdigul, J. (2011), Evidence of Cell-Associated Proteinases from Virgibacillus sp. SK33 Isolated from Fish Sauce Fermentation. Journal of Food Science, 76: C413–C419. doi: 10.1111/j.1750-3841.2011.02058.x
- Issue published online: 6 APR 2011
- Article first published online: 14 MAR 2011
- MS 20101053 Submitted 9/18/2010, Accepted 12/28/2010.
- cell-associated proteinases;
- NaCl-stable enzyme;
- Virgibacillus sp.
Abstract: Cell-associated proteinases from Virgibacillus sp. SK33 isolated from fish sauce fermentation were extracted and characterized. Proteinases were effectively released when washed cells were incubated in 0.3 mg/mL lysozyme in 50 mM Tris-maleate (pH 7) at 37 °C for 2 h. Major cell-associated proteinases exhibited molecular mass of 17, 32, and 65 kDa, but only a 32-kDa proteinase showed strong amidolytic activity toward Suc-Ala-Ala-Pro-Phe-AMC. Activity of all cell-associated proteinases was completely inhibited by phenylmethanesulfonyl fluoride, indicating a characteristic of serine proteinase. In addition, a 65-kDa serine proteinase was also inhibited by ethylenediaminetetraacetic acid, implying a metal-dependent characteristic. Optimum activity toward a synthetic peptide substrate was at 50 °C and pH 8 and 11. Proteinases with molecular mass of 17 and 32 kDa exhibited caseinolytic activity at 25% NaCl and activity based on a synthetic peptide substrate increased with NaCl concentrations up to 25%, suggesting their role in hydrolyzing proteins at high salt concentrations. This is the first report of liberated cell-associated proteinases from a moderate halophile, Virgibacillus sp.
Practical Application: The cell-associated proteinases could be extracted from Virgibacillus sp. SK 33 using lysozyme. The extracted enzyme could be applied to hydrolyze food proteins at NaCl content as high as 25%. In addition, this study demonstrated that not only extracellular but also cell-associated proteinases are key factors contributing to protein-degrading ability at high salt environment of Virgibacillus sp. SK 33.