Abstract:
In this paper, we found a 702 bp gene
Lysin132 encoding phage endolysin from the genome of a bacteriophage BVE2 derived from sediments of the Southwest Indian Ocean. Lyins132 contains a total of 234 amino acid residues, and its molecular weight is estimated to be 25.74 kDa. Result of homologous amino acid sequence alignment shows that BVE2 Lysin132 has multiple amidase active sites. Phylogenetic tree analysis showed that BVE2 Lysin132 is an N-acetylmuramyl-L-alanine amidase. The BVE2
Lysin132 gene was cloned into pEASY-Blunt E2 Expression Vector to construct
E. coli-pEASY-
Lysin132 expression strain. Thus, it successfully induced an expression with IPTG to obtain a large number of recombinant BVE2 Lysin132 with 6×His tag. After purification by a nickel column, SDS-PAGE electrophoresis yielded a single target protein band. Results of enzymatic properties analysis show that the optimal reaction temperature of recombinant BVE2 Lysin132 is 30 ℃, which has good thermal stability at medium and high temperature. Incubating at 10-50 ℃ for 90 minutes can still maintain more than 70% of the enzyme activity; The optimum pH is 7.0, and it can maintain more than 80% of the enzyme activity at pH 6.0-8.0, indicating that the enzyme has a wide pH range. Na
+, Mg
2+ can significantly increase the enzyme activity by more than 20%, and Ca
2+ can increase the enzyme vitality by more than 40%. Results of antibacterial experiments showed that recombinant BVE2 Lysin132 had a better inhibitory effect on Gram-negative bacteria, especially
Vibrio alginolyticus, V. campbellii, V. harveyi, and had much better inhibitory effect. Compared with available microbial lysozyme, the inhibitory effect increased by more than 40%. Therefore, this article has obtained a lysozyme with a wide pH range and good thermal stability, which can provide an important theoretical basis for the development of new antibacterial agents for aquaculture, food preservation, medicine applications and so.