Antimicrobial phenolic compounds from <Emphasis Type="Italic">Enterococcus faecium</Emphasis> S29 (EU 158188): characterization and production optimization

The present study aimed to investigate and optimize the promising antagonistic activity of the exogenous Enterococcus faecium S29 (EU 158188) isolated from the heavily polluted coastal waters of Alexandria, Egypt. Statistical designs, mutations and immobilization were used as optimization procedures. Cells grown in Luria-Bertani and/or UV-treated medium showed optimum activity compared to those grown under basal conditions or ethidium bromide treatment as well as wild-type variants. Immobilization decreased the antagonistic activity of E. faecium compared to their free cells. Ethyl acetate extract (12 organic compounds) exhibited the highest antimicrobial activity and was dominated by phenol (52.11%) and 1, 2 Benzenedicarboxylic acid, diisooctyl ester (29.44%) with molecular weights 94 and 390.28, respectively. Thin-layer chromatography (TLC) fractionation of the bioactive compounds showed two spots with RF: 0.32 and 0.61 with the latter exhibits a broad spectrum of antagonistic activity against six reference pathogens {Staphylococcus aureus (ATCC 6538), Streptococcus faecalis (ATCC 8043), Pseudomonas aeruginosa (ATCC 8739), Escherichia coli (ATCC 8739), Micrococcus luteus (ATCC 10240) and Candida albicans}. The yellow gelatinous purified compound was characterized by an aromatic odor; λ _{max =} 0.629 at 210 nm and IR spectrum IR (K Br): 1750 ester].