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To study the effects of sea microalgae exometabolites on reproduction of pathogenic bacteria.Experiments were performed with unialgal cultures of sea microalgae Phaeodactylum tricornutum, Chlorella minutissima, Chroomonas salina. Strains of Lysteria monocytogenes 4b, Staphylococcus aureus, Salmonella typhimurium with typical cultural, morphologic, biochemical and antigenic characteristics were used as model bacteria. Cultivation of microalgae was performed in synthetic and natural sea water (salinity 32 per thousand). The algae were grown on modified Goldberg medium. Natural sea water was taken in different seasons of year. Exometabolites were obtained by extraction from microalgae cultural fluid with solvents in the order of increase of their polarity (hexane, benzol, ethyl acetate) as appropriate fractions (HF, BF, EAF).Obtained fractions of exometabolites of sea microalgae cultivated in synthetic sea water influenced weakly on the reproduction of pathogenic bacteria, which differed depending on type of both microalga and microorganism. However EAF fraction of exometabolites of P. tricornutum obtained during its cultivation in natural sea water (especially obtained in summer time) significantly stimulated growth of all tested microorganisms.It is possible that stimulation of growth of pathogenic bacteria could be caused by either changes of medium composition (and, consequently, appearance of other metabolites than in synthetic sea water) or enhancement of effect of microalgae's own metabolites by metabolites of natural sea water, in which plenty organic compounds produced by numerous sea inhabitants exist. |
