The Use of HPLC for Determination of Expression Product of Microbial Tyrosine Decarboxylase
The aim of this study was verification of the presence or absence of specific DNA sequences coding for tyrosine decarboxylase in the starter cultures used in the fermented sausages production and confirmation of the tyrosine decarboxylase gene expression by rapid HPLC analysis affording the expression product − tyramine.
Genomic DNA from microorganisms used as starter cultures for production of fermented sausages was extracted with phenol. The DNA was used as a template for PCR identification in which a set of oligonucleotide primers based on tyrosine decarboxylase gene sequence was used. Two strains with high tyrosine decarboxylase activity were detected (Lactobacillus curvatus and Lactobacillus sake). The tyrosine decarboxylase gene expression of these two strains was analyzed by an optimized rapid HPLC method, which confirmed the presence of high concentrations of tyramine. The results show suitability of the described PCR and HPLC methods of screening starter cultures for the presence and expression of the above gene.