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Emilia García-Moruno

Publications and source records attributed to Emilia García-Moruno.

2 recordsLinked to original sources

A rapid and inexpensive method for the determination of biogenic amines from bacterial cultures by thin-layer chromatography.

This study describes a simple, rapid, and inexpensive method to determine the ability to produce biogenic amines (BA) by bacteria in liquid culture media containing the corresponding amino acid precursor. In view of their role as starters in food fermentation, BA formation by these microorganisms has to be taken into consideration by selecting appropriate strains. For the standardization of the assay pure BA were mixed. The method avoids a prior extraction step of the amines and allows the separation and identification of the amines histamine, tyramine, putrescine, and phenylethylamine using thin-layer chromatography. The method was successfully applied to several BA-producer bacterial strains. This method constitutes a simple solution to the previous reports describing false-positive reactions in routine screening procedures generally involving the use of a differential medium containing a pH indicator.

Amino Acids↗

The tyrosine decarboxylation test does not differentiate Enterococcus faecalis from Enterococcus faecium.

According to the current edition of the Bergey's Manual of Systematic Bacteriology [11] the tyrosine decarboxylation test allows the differentiation of enterococci. Tyrosine is decarboxylated to the biogenic amine tyramine by E. faecalis and not by E. faecium strains. In the present study we sequenced the16S rDNA of two tyramine-producing strains, BIFI-56 and BIFI-58, presumptively classified as E. faecalis. Their 16S rDNA were identical to the same fragment from the E. faecium type strain. Several E. faecium strains were then checked for their ability to decarboxylate tyrosine and also a putative tyrosine decarboxylase-coding gene was PCR amplified from these strains. All the strains confirmed as E. faecium produced tyramine and possessed a DNA fragment coding for a putative tyrosine decarboxylase. The concordance of the two methods allows us to conclude that the tyrosine decarboxylase test cannot be used in the differentiation of E. faecalis from E. faecium since at least some E. faecium strains are tyramine producers.

Bacterial Typing Techniques↗