Dominance and diversity of archaea in food‐grade salts: insights for histamine degradation in salt‐fermented foods

SummaryHalophilic archaea (haloarchaea) are extremophilic microorganisms that thrive and dominate in hypersaline environments, including salt and salt‐fermented foods. Haloarchaea present in salt are integral to the safety of salt‐fermented foods. In this study, haloarchaeal communities in seven food‐grade coarse sea salts, commonly used in salt‐fermented food production, were studied. q‐PCR results showed that archaea represented the dominant group in all samples, with relative abundances above 83%. Archaeal 16S rRNA gene amplicon sequencing identified thirty‐three of the current eighty‐five genera within the class Halobacteria across the samples, revealing unique haloarchaeal community compositions. A total of 394 haloarchaeal strains, grouped into forty‐one species from twenty current genera and potentially novel taxa, were isolated. Archaeal community composition in all samples varied significantly among genera. Notably, a significant proportion of the haloarchaeal strains demonstrated histamine degradation capabilities, confirmed by bioinformatic analyses and culture‐based methods. Our results indicated that haloarchaea from salt can potentially serve as starter cultures for salt‐fermented foods, maintaining low histamine levels.