THE INFLUENCE OF THE CELL FREE SOLUTION OF LACTIC ACID BACTERIA ON TYRAMINE PRODUCTION BY FOOD BORNE-PATHOGENES IN TYROSINE DECARBOXYLASE BROTH

摘要

The function of cell-free solution of lactic acid bacteria (LAB) on tyramine production by different food borne-pathogenes (FBPs) including Salmonella parathypi A, Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli was investigated intyrosine decarboxylase broth (TDB). Cell free solutions were prepared from Leuconostoc mesenterodies subsp. cremoris, Pediococcus acidophilus, Lactococcus lactis subsp. lactis, Streptococcus thermophilus. The cell-free solution ratio was 1:1 (CFS: medium/5ml:5ml v/v) and 1:3 (CFS: medium/2.5ml:7.5ml, v/v) each lactic acid bacteria used and there was no CFS in control group. Tyramine and the other amine production by food borne-pathogens were tested in TDB using HPLC. Both of concentration CFS of Streptococcus thermophilus and Pediococcus acidophilus (1:1) inhibited tyramine production (98%) by S. parathypi A. Tyramine production by E. coli was also inhibited by all of the CFSs. The inhibitor effect of CFS of P. acidophilus (1:1) was the highest for tyramine production (55%) by L. monocytogenes, following CFS of Lc. lactis subsp. lactis and Leu. mes. subs, cremoris (1.1) (20%) while CFS of Leu. mes. subsp. cremoris and Lc. lactis subsp. lactis (1:3) showed stimulator effect (160%). The stimulation effects of CFS of 5". thermophilus and lc. lactis subsp. lactis (1:1) were more than 70% on tyramine formation by S. aureus comparing to control. Consequently, CFSs from LAB strains decrease pH quickly and inhibit the accumulations of tyramine, ammonia, cadaverine, putrescine and tryptamine.