ANTIMYCOPLASMA PROPERTIES AND APPLICATION IN CELL-CULTURE OF SURFACTIN, A LIPOPEPTIDE ANTIBIOTIC FROM BACILLUS-SUBTILIS

Surfactin, a cyclic lipopeptide antibiotic and biosurfactant produced by Bacillus subtilis, is well-known for its interactions with artifici al and biomembrane systems (e.g., bacterial protoplasts or enveloped v iruses), To assess the applicability of this antiviral and antibacteri al drug, we determined the cytotoxicity of surfactin with a 50% cytoto xic concentration of 30 to 64 mu M for a variety of human and animal c ell lines in vitro, Concomitantly, we observed an improvement in proli feration rates and changes in the morphology of mycoplasma-contaminate d mammalian cells after treatment with this drug, A single treatment o ver one passage led to complete removal of viable Mycoplasma hyorhinis cells from various adherent cell lines, and Mycoplasma orale was remo ved from nonadherent human T-lymphoid cell lines by double treatment, This effect was monitored by a DNA fluorescence test, an enzyme-linked immunosorbent assay, and two different PCR methods. Disintegration of the mycoplasma membranes as observed by electron microscopy indicated the mode of action of surfactin, Disintegration is obviously due to a physicochemical interaction of the membrane-active surfactant with th e outer part of the lipid membrane bilayer, which causes permeability changes and at higher concentrations leads finally to disintegration o f the mycoplasma membrane system by a detergent effect, The low cytoto xicity of surfactin for mammalian cells permits specific inactivation of mycoplasmas without significant deleterious effects on cell metabol ism and the proliferation rate in cell culture. These results were use d to develop a fast and simple method for complete and permanent inact ivation of mycoplasmas in mammalian monolayer and suspension cell cult ures.