The aim was to monitor production of eight biogenic amines (BAs) (histamine, tyramine (TYR), tryptamine, putrescine, cadaverine (CAD), phenylethylamine, spermine and spermidine) by selected 81 lactic acid bacteria (LAB) strains: Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Pediococcus, Tetragenococcus and Bifidobacterium. The tested LAB and bifidobacteria were isolated from dairy products and beer. The decarboxylase activity of the micro-organisms was studied in growth medium after cultivation. The activity was monitored by HPLC after the pre-column derivatisation with dansylchloride. Fifty LAB showed decarboxylase activity. Thirty-one strains produced low concentrations of CAD (£10 mg L )1 ). Almost 70% of beer isolates generated higher amounts of TYR (£3000 mg L )1 ). Most of the tested LAB demonstrated decarboxylase activity. The above micro-organisms can contribute to the increase of content of BAs in dairy products or beer and thereby threaten food safety and health of consumers. Production of BAs even by the representatives of some probiotic strains (Bifidobacterium and Lactobacillus rhamnosus) was detected in this research. This study has also proved that contaminating LAB can act as sources of higher amounts of CAD and TYR in beer.
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The aim of this study was to monitor the antibacterial effect of seven phosphate salts on selected strains of Gram-negative and Gram-positive bacteria, which could be considered responsible for food-borne diseases (Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Micrococcus luteus, Staphylococcus aureus, Citrobacter freundii, Escherichia coli, Proteus mirabilis, Salmonella enterica ser. Enteritidis and Pseudomonas aeruginosa). For these purposes, phosphates differing in chain length were used. The tested concentrations were in the range of 0.1-2.0% (wt v(-1)) applied at the model conditions. In the majority of cases the visible inhibitory effect on the growth of observed microorganisms could be seen. Due to the chemical structure of salts and their dissociation both the pH values of cultivation broth and similarly the growth characteristics of bacterial strains were affected. The inhibition of above mentioned bacteria was apparently supported by this dissociation. Phosphates obviously made the development of most Gram-positive bacteria impossible. Especially Micrococcus luteus was extremely sensitive to the presence of these substances. On the other hand, Gram-negative bacteria seemed to be resistant to the phosphate incidence. The exemption clause from the tested salts was represented by a high alkaline trisodium phosphate. It should be pointed out that generally the most significant antibacterial effects were shown by polyphosphates HEXA68 and HEXA70, trisodium phosphate undecahydrate, tetrasodium pyrophosphate and finally trisodium phosphate. By comparing the inhibitory effects of various phosphate salts can be concluded that the antibacterial activity was not determined only by the condensation degree but there was also proved the dependence on pH values.
Summary
The ability of typical probiotic culture of Bifidobacterium to produce biogenic amines could be considered a contrastive feature to the beneficial dietary effect on human health. The aim of this pilot study was to evaluate the decarboxylase activity of Bifidobacterium animalis subsp. lactis CCDM 239 influenced by selected factors (pH 4.5 and 5.0; the contents of NaCl 0–20.0 g L−1, glucose and lactose 0–10.0 g L−1) at in vitro conditions. The kinetics of the biogenic amine production under the above‐mentioned conditions was also monitored. The biogenic amine content detection was carried out in the supernatants of inoculated broth [MRS enriched with amino acids: arginine, ornithine, lysine, tyrosine; 3 g L−1 after the cultivation (48 h, 37 ± 1 °C)]. RP‐HPLC after the precolumn derivatisation with dansyl chloride was used. In most cases, the low concentrations of tyramine were monitored (<15 mg L−1). Simultaneously, it was found out that the addition of certain fermentable saccharide concentrations and NaCl in their mutual combination seemed to have supporting effect on the decarboxylase activity of the tested Bifidobacterium.
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