Isolation and Identification of Staphylococcus epidermidis S14 Screening Extracellular Antimicrobial Metabolites

Abstract

Total 24 isolates with antimicrobial activity against Staphylococcus aureus, Escherichia coli, Bacillus cereus and Shigella castellani, out of 259 strains, were isolated from the internal of seven marine fishes. The extracellular metabolites of strain S14, isolated from the internal of shark, showed stronger inhibition against the four tested bacteria, including G- and G+ bacteria. Based on the 16S rDNA the sequencing analysis, the strain S14 belonged to a member of Staphylococcus epidermidis with 99% DNA similarity and named to Staphylococcus epidermidis S14. The Staphylococcus epidermidis S14 secreted rarely antibacterial substance in the stabilization period and the antibacterial active substances might be the secondary metabolites. The antibacterial metabolites were not hydrolyzed by pepsin, trypsin and lysozyme. The antibacterial metabolites were stable for 30 min to high temperature treatment at 100°C and had higher antibacterial activity at neutral pH.