Marcobal Angela, de las Rivas Blanca, García-Moruno Emilia, Muñoz Rosario
Departamento de Microbiología, Instituto de Fermentaciones Industriales, CSIC, Madrid, Spain.
Syst Appl Microbiol. 2004 Aug;27(4):423-6. doi: 10.1078/0723202041438428.
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.
根据最新版的《伯杰氏系统细菌学手册》[11]，酪氨酸脱羧试验可用于区分肠球菌。粪肠球菌可将酪氨酸脱羧生成生物胺酪胺，而屎肠球菌菌株则不能。在本研究中，我们对两株产酪胺菌株BIFI - 56和BIFI - 58的16S rDNA进行了测序，这两株菌初步鉴定为粪肠球菌。它们的16S rDNA与屎肠球菌模式菌株的相同片段一致。随后检测了几株屎肠球菌菌株的酪氨酸脱羧能力，并从这些菌株中PCR扩增出一个假定的酪氨酸脱羧酶编码基因。所有经确认的屎肠球菌菌株都能产生酪胺，并拥有一个编码假定酪氨酸脱羧酶的DNA片段。这两种方法的一致性使我们得出结论，酪氨酸脱羧酶试验不能用于区分粪肠球菌和屎肠球菌，因为至少一些屎肠球菌菌株是酪胺产生菌。
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