The obtaining and properties of biosurfactants synthesized by bacteria of the genusLactobacillus

Lactic acid bacteria were subjected to screening for the ability of the analyzed strains to synthesize surface-active compounds. The most favorable synthesis of biosurfactants was observed in the culture of Lactobacillus casei 8/4, thus this strain was applied in the subsequent stages of the study. The research enabled determining the optimal conditions of biosurfactants synthesis, which was shown to be mainly determined by the composition of the culture medium and growth phase of L. casei 8/4. Aqueous solutions of biosurfactant preparations displayed antimicrobial activity against the test pathogenic species: Staphylococcus aureus 11, Bacillus subtilis T91, and Micrococcus roseus R2. Analyses conducted with the FTIR demonstrated that biosurfactants were constituted by protein fractions and polysaccharide fractions, i.e. possessed the structure typical of glycoproteins, which is affected by medium composition and the phase of growth of the biosurfactants-synthesizing strain. The same factors determine the structure of proteins in glycoproteins, which was confirmed after electrophoretic separation with the NuPAGE method.