89B-34 |
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S. DATTA1, Q. G. Xue2, M. E. Janes1, J. N. Losso1, and J. F. Lapeyre3. (1) Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200, (2) Department of Veterinary Science, Louisiana State Univ. Agricultural center, Baton Rouge, LA 70803, (3) Dept. of Veterinary Science, Louisiana State Univ. Agricultural center, Baton Rouge, LA Lysozyme (muramidase)is a food grade antimicrobial approved for use in several countries. Hen egg white is the major source of lysozyme for commercial applications. However, in recent years, there has been increasing interest in the distribution and characterization of invertebrate i-type lysozymes which include lysozyme from bivalve molluscs. Lysozyme from bivalve molluscs are generally more active at lower temperature, pH and, higher salt concentration than Hen egg white lysozyme and therefore may be better suited for use in food and pharmaceutical industries. Eastern oysters, Crassostrea virginica are found in coastal waters of the Atlantic and Gulf of Mexico, USA. High lysozyme activity is detected in fluid filling the shell cavity of oysters. The combination of this fluid and plasma released when oysters are shucked is commonly referred to as ‘shell liquor'. Shell liquor is currently discarded by the oyster industry. Lysozyme was purified from the shell liquor of eastern oysters using a combination of ion exchange chromatographies. Lyophilized shell liquors adjusted to pH 5.0 using sodium acetate buffer were desalted on Sephadex G-25 column, separated on Q-Sepharose FF column, and CM-Sepharose FF column, respectively. The lysozyme activities of each of the fraction were tested and aliquots showing high lysozyme activity were subjected to SDS-PAGE. Fractions showing a single protein band were pooled together. The molecular weight of the purified lysozyme was estimated to be 18 KDa by SDS-PAGE. Hen egg white lysozyme is about 14.4 KDa. Oyster lysozyme activity was found to be 2.0 x 103 U/ml where one unit of lysozyme is defined as the quantity which causes a decrease in absorbance of 0.001 per minute of Micrococcus lysodeikticus.
Session 89B, Aquatic Food Products: Surimi, gels and by-products
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |