Growth characteristics of histamine-producing lactic acid bacteria isolated from marinade broth in shimesaba production

¹Takewa Suisan Co., LTD., Hachinohe, Aomori 031-0841, ²National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama, Kanagawa 236-8684, ³Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Sapporo, Hokkaido 062-0922, Japan

To characterize the histamine-producing bacteria isolated from a marinade broth accumulating approximately 25 mg/100 mL of histamine in shimesaba production, taxonomic and physiological features of the isolates were studied. Nineteen strains capable of producing histamine were isolated from a marinade broth by using AC plate agar with the anaerobic culture method and a member of lactobacilli was identified based on the phenotypic characteristics. Moreover, the closest phylogenetic neighbor of the strains was Lactobacillus otakiensis sharing 100% similarity based on 16S rRNA gene sequence. The strains harbored a pyruvoyl-dependent histidine decarboxylase gene, which is widespread in histamine-producing gram positive bacteria. Growth of the strains was inhibited by low pH (below 3.6), low water activity (below 0.939), high salt concentration (above 10%), and supplementation of 2% acetic acid (final concentration). However, all of the strains were able to grow in MRS broth with pH 5.7 at temperatures below 8℃ and produce histamine within 4 weeks of cultivation. To prevent histamine accumulation in shimesaba production, it is necessary to use some bacteriostatic conditions, low pH (around 4.0), low temperature (below 8℃), and an appropriate concentration of vinegar, to preserve marinade broth based on the hurdle technology theory.