Study of Inhibitory agent produced by Streptococcus thermophilus on growth and Biofilm formation for some pathogenic bacteria

Abstract

Inhibitory activity of Streptococcus thermophilus unconcentrated and concentrated filtrate was studied against some pathogenic bacteria included: Pseudomonas aeruginosa, Klebsiella spp., Staphylococcus aureu, Escherichia coli. Inhibitory activity of protein that extracted from S. thermophilus concentrated filtrate was studied after precipitate by ammonium sulphate and inhibitory activity of lipophilic fraction that extracted from concentrated filtrate with chloroform-methanol (1:1 vol/ vol) was studied against pathogenic bacteria. Also inhibitory activity of biosurfactant produced by S. thermophilus was studied against growth and biofilm formation for pathogenic bacteria. The results showed that unconcentrated and concentrated filtrate had inhibitory activity against all pathogenic bacteria. Also protein and lipophilic fraction had inhibitory effect against pathogenic bacteria, while the biosurfactant show inhibitory activity against growth of all pathogenic bacteria but show inhibitory effect on biofilm formation only for pathogenic bacteria S. aureus and E. coli.