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 Octopus maya, 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 (hdc), ornithine (odc), and lysine decarboxylases (ldc) 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 Hafnia alvei. NR73 represented 18.8% of the total isolates and showed 98% homology with Enterobacter xianfengensis and Enterobacter cloacae. NR6A represented 6% of the total isolates, which were identified as Lactococcus sp. The hdc gen from NR6B showed 100% identity with hdc from Morganella morganii; ldc showed 97.7% identity with ldc from Citrobacter freundii. The Odc gene was detected only in NR73 and showed 100% identity with Enterobacter 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.