Comparison of antibacterial effect of seven 1-monoglycerides on food-borne pathogens or spoilage bacteria

The aim of this study was to compare under the same conditions in vitro the inhibitory effects of seven 1-monoglycerides (MAG) containing fatty acids with a medium chain on ten strains of food-bome pathogens or spoilage gram-positive and gram-negative bacteria (Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Micrococcus luteus, Staphylococcus aureus, Citrobacter fieundii, Escherichia coli. Proteus mirabilis, Salmonella enterica ser. Enteritidis and Pseudomonas aeruginosa) and on their growth indicatos. The inhibitory effect of MAGs (monocaprylin, monocaprin, monolaurin, monomyristin, monopalmitin, MAG of undecanoic and 10-undecenoic acids) at a concentration of 25 - 1500 mg.l(-1) was observed. Growth of bacteria in the presence of MAG was studied by means of optical density of bacteria for 24 h. The data were modelled through a Gompertz equation and the lag-time, the maximum specific growth rate and the maximal value reached were calculated. MAGs inhibited mainly the growth of gram-positive bacteria, which was shown by the extended lag-time, decrease in specific growth rate and decrease in cell density. Inhibitory effects of tested MAGs could be ranked from point of view of the minimum inhibitory concentration: MAO-C12:0 > MAO-C 11:0 > MAO-C I 0:0 > MAO-C14:0 > MAO-C11:1 > MAG-C8:0 > MAO-C16:0. In vitro, no significant inhibitory effects of 1-monoglycerides, with the exception of the highest concentrations applied, on the growth of gram-negative bacteria were detected. The main contribution of this study is to compare the effects of several MAG containing fatty acids with a medium chain under the same conditions on the growth indicators of bacteria.