Abstract

In present study, we aimed to express T4 Lysozyme gene (gene e) in Streptococcus salivarus subsp. thermophilus to create better probiotics for poultry. The Esherichia coli plasmid, Bluescript II SK +/- harboring gene e named pL1, was converted to a new E. coli-Streptococcus sp. shuttle vector (pL2) by cloning and insertingStreptococcal replication origin of pTRW10 vector into pL1. pL2 plasmid isolated from E. coli was introduced into S. salivarius subsp. thermophilus and Lactococcus lactis cells by electro-transformation. The lysozyme enzymes expressing by these bacteria were found to be active on Micrococcus luteus cells and thereby preventing their growth on assay plates. Thermostability of these enzymes from the recombinant bacteria was also found different from each other. The lysozyme expressed by S. salivarius subsp. thermophilus cells seemed to increase its capacity for thermoresistance and was not denaturated at 70°C for 15 min. In contrast, the enzyme expressed by L. lactis and E. coli cells were easily denaturated when exposed to the same temperature treatment.

Key words: Expression, lysozyme, Streptococcus salivarius subsp. thermophilus,thermostability.