Degradation of biogenic amines and histamine reduction in salted anchovy fermentation by Halalkalibacterium halodurans SK35-1

Biogenic amines (BAs), which are commonly present in various naturally fermented foods, are associated with adverse effects on consumer health. The accumulation of BAs commonly occurs under unhygienic conditions during raw material preparation, improper storage, and uncontrolled fermentation. BAs can be degraded by certain microorganisms through oxidative deamination activity. In this study, factors influencing the degradation of BAs by strain SK35-1, isolated from fish sauce fermentation, were examined. In addition, the ability of strain SK35-1 to mitigate histamine buildup during salted fish fermentation was assessed. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that SK35-1 shares 100 % similarity with Halalkalibacterium halodurans. The strain exhibited efficient degradation of BAs, ranked in descending order as follows: putrescine ≈ cadaverine > tyramine > tryptamine > histamine > spermidine > spermine. Optimal conditions for BA reduction were identified as 30 °C–40 °C, pH 6–8, and 10 % NaCl when cultivated in modified Møller broth. BA degradation was notably more effective at lower initial BA concentrations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) zymography revealed a 45.7-kDa amine oxidase with activity against putrescine, cadaverine, spermidine, and spermine. The presence of amine dehydrogenase activity specific to histamine was confirmed through native-PAGE and enzyme assays. In salted anchovy fermentation, samples inoculated with H. halodurans SK35-1 exhibited a 19.7 % reduction in histamine levels compared to the uninoculated control. In addition, H. halodurans SK35-1 modulated volatile compound formation in fermented anchovy by suppressing off-odor compounds such as methyl thioacetate, while enhancing distinct volatiles of fermented fish, including 2-methyl-1-butanol, 3-methyl-1-butanol, 1-penten-3-ol, and 3-methyl-butanoic acid. These findings suggest that H. halodurans SK35-1 might have potential for controlling BAs without forming undesirable volatile compounds in fermented food products.