Antivibrio activity of recombinant lysozyme expressed from black tiger shrimp, Penaeus monodon

The gene coding for lysozyme in black tiger shrimp (Penaeus monodon) was cloned, sequenced and expressed in pEXP5-NT/TOPO vector. The deduced amino acid sequence of P. monodon lysozyme showed 95-98% similarity to that of other shrimp such as Litopenaeus vannamei, Fenneropenaeus chinensis, Marsupenaeus japonicus and freshwater prawn Macrobrachium rosenbergii. The lysozyme was purified to homogeneity and observed as a band of approximately 20 kDa in 15% SDS-PAGE. Bacteriolytic activity of lysozyme against different bacterial cultures was determined by solid phase as well as turbiditimetric assay. Lysis was obtained against a broad range of Gram positive and Gram negative bacteria. A gradual decrease in lysozyme activity was observed with respect to time by turbiditimetric assay. Minimal inhibitory concentration (MIC) of purified shrimp lysozyme for Vibrio harveyi was 0.47 μg/ml and for Micrococcus luteus, (MIC) 0.12 μg/ml. The lysozyme was found effective against V. harveyi when tested in sea water with and without EDTA.