The histamine is generated by decarboxylation of the histidine through histidine decarboxylase enzymes derived from the bacteria present in food. Bacterial histidine decarboxylases have been extensively studied and characterized in different organisms, and two different enzyme groups have been distinguished: pyridoxal phosphate-dependent and pyruvoyl-dependent enzymes. Pyridoxal phosphate-dependent histidine decarboxylases are encountered in Gram-negative bacteria belonging to various species. Pyruvoyl-dependent histidine decarboxylases are found in Gram-positive bacteria, especially in lactic acid bacteria implicated in food fermentation or spoilage food. Typically, histamine in fermented food is the result of decarboxylation of histidine by Gram-positive lactic acid bacteria and Gram-negative enteric bacteria. These microorganisms possess hdc genes encoding for histidine decarboxylases which are responsible for the production of histamine from free amino acids. Tetragenococcos can produce histidine decarboxylase that it converts histidine to histamine. However, the ability of bacteria to decarboxylate histidine is highly variable. It depends not only on the species but also on the fermentation process and the environmental conditions. Tetragenococcus have been characterized and identified based on phenotypic characteristics and DNA–DNA relatedness. For the identification of Tetragenococcus strains, the phenotypic characteristics were found in a wide variety of conditions such as in sugar fermentation. However, the phenotypic identification is very complicated and the results obtained are to some extent inaccurate and time-consuming. The application of molecular methods based on 16S rRNA gene restriction and 16S rRNA gene sequence analysis achieves quick and accurate identification of these microorganisms.