Molecular Characterization of Histamine-Producing Psychrotrophic Bacteria Isolated from Red Octopus (Octopus maya) in Refrigerated Storage

Abstract

The present study aimed at determining the histamine production capacity of Gram (+) and Gram (-) bacteria isolated from <i>Octopus maya</i>, along with identifying the presence of amino acid decarboxylase genes. Of the total 80 psychrotrophic microorganisms, 32 strains were identified as histamine-forming bacteria. The recombinant DNA technique was used for genotypic identification of histidine (<i>hdc</i>), ornithine (<i>odc</i>), and lysine decarboxylases (<i>ldc</i>) genes. Thirty-two strains were able to produce 60⁻100 ppm in trypticase soy broth with 1.0% l-histidine after 6 h at 20 °C. NR6B showed 98% homology with <i>Hafnia alvei</i>. NR73 represented 18.8% of the total isolates and showed 98% homology with <i>Enterobacter xianfengensis</i> and <i>Enterobacter cloacae</i>. NR6A represented 6% of the total isolates, which were identified as <i>Lactococcus</i> sp. The <i>hdc</i> gen from NR6B showed 100% identity with <i>hdc</i> from <i>Morganella morganii</i>; <i>ldc</i> showed 97.7% identity with <i>ldc</i> from <i>Citrobacter freundii</i>. The <i>Odc</i> gene was detected only in NR73 and showed 100% identity with <i>Enterobacter</i> sp. All the isolated were identified as weak histamine⁻former. The ingestion of a food containing small amounts of histamine has little effect on humans; however, the formation of biogenic amines is often considered as an indicator of hygienic quality; this emphasizes the importance of improving good management practices and storage.