Biogenic amine–producing Enterococcus spp. from anchovy (Engraulis encrasicolus): Isolation and molecular insights

Biogenic amines (BAs) constitute an important chemical hazard in fish and fishery products, primarily due to their adverse effects on human health. While histamine-producing bacteria have been extensively investigated, the contribution of Enterococcus species to BA formation in fresh marine fish remains poorly characterized. The present study aimed to isolate and identify Enterococcus spp. from fresh anchovy (Engraulis encrasicolus) and to evaluate their capacity to produce major BAs. A total of 56 fresh anchovy samples were analyzed, yielding 24 Enterococcus isolates that were characterized by phenotypic methods and 16S rRNA gene sequencing. The BA production capacities of the isolates were quantified via HPLC following incubation in a standardized liquid screening medium under optimized laboratory conditions. Fourteen isolates (58.33%) exhibited aminogenic activity and were identified as Enterococcus faecalis (42.86%), E. faecium (28.57%), E. lactis (21.43%), and E. durans (7.14%). Tyramine, histamine, tryptamine, cadaverine, and putrescine were detected, with maximum concentrations reaching 307.638, 257.939, 236.928, 165.835, and 56.317 mg/L, respectively. The highest total BA levels, E. faecium BLK18, exhibited the highest levels, reaching 493.547 mg/L. These findings demonstrate that fresh anchovies may serve as a reservoir for aminogenic Enterococcus spp. and highlight their potential role in BA accumulation beyond traditionally implicated bacteria. The results support the inclusion of Enterococcus species in routine monitoring programs for fresh fish products and underline the need for broader, evidence-based strategies to manage BA-related hazards in seafood.