Determination of minimum inhibitory concentrations of lactic acid bacteria and other antagonist microorganisms

Minimum inhibitory concentrations of lactic acid bacteria and other antagonist microorganisms isolated from natural sources of Kaliningrad region (soil, water bodies, plant objects) were determined. It was shown that the minimum inhibitory concentration of Pediococcus pentosaceus metabolites against Escherichia coli is 1.5·107 CFU/ml; Pseudomonas chlororaphis metabolites have no inhibitory effect against the test strain of Escherichia coli under study. It was found that Pediococcus damnosus metabolites adversely affect the growth of Escherichia coli, but at a concentration of 1.5·107 CFU/ml after 6-24 hours of cultivation. For metabolites isolated by Lactobacillus casei, the characteristic minimum inhibitory concentration with respect to the studied Escherichia coli strain is 1.5-107 CFU/ml, and for metabolites isolated by Lactobacillus fermentum, the minimum inhibitory concentration with respect to the studied Escherichia coli strain is 1.5·105 CFU/ml. At a concentration of Bacteroides hypermegas (Megamonas hypermegale) metabolites equal to 1.5·106 CFU/ml, an optical density lower than that of the control is observed. The minimum concentration of Pseudomonas syringae metabolites inhibiting Escherichia coli culture growth is 1.5-107 CFU/ml. For the metabolites Acetobacter aceti and Psychrobacter urativorans, the concentration of 1.5·107 CFU/ml is the lowest to inhibit the growth of Escherichia coli.