RESUMO
The aims of this study were to isolate halophilic lactic acid bacteria possessing aspartate decarboxylase and elucidate the property of the isolates as starter cultures for fish sauce fermentation. Seventy-four strains were isolated from fermented fish foods on aspartate indicator broth containing bromocresol purple, and all isolates were identified as Tetragenococcus halophilus and confirmed to possess the aspartate decarboxylase gene (aspD) by PCR amplification. The isolates were classified into 14 groups based on their aspD-encoding plasmid construction. Strains selected from each group and a control strain incapable of aspartate decarboxylation were inoculated into fish sauce mash as starter cultures. Isolated strains possessing aspD converted aspartate into alanine almost completely in the fish sauce mash. In addition, the strains prevented the accumulation of biogenic amines, as did the control strain, whereas various amines were accumulated in fish sauce mash without starter cultures. Sensory evaluation tests indicated that converting the sour amino acid aspartate into the sweet amino acid alanine made the fish sauce taste milder. In conclusion, the use of T. halophilus possessing aspartate decarboxylase as a fish sauce fermentation starter causes the conversion of aspartate to alanine, accompanied by taste alteration, and prevents biogenic amine accumulation in fish sauce products.
Assuntos
Carboxiliases/metabolismo , Fermentação , Produtos Pesqueiros/microbiologia , Microbiologia de Alimentos , Lactobacillales/enzimologia , Adulto , Alanina/metabolismo , Aminoácidos/metabolismo , Ácido Aspártico/metabolismo , Aminas Biogênicas/análise , Carboxiliases/genética , Enterococcaceae/isolamento & purificação , Humanos , Plasmídeos/genética , Paladar , Adulto JovemRESUMO
A new halicyclamine derivative, tetradehydrohalicyclamine B (1), was isolated from the marine sponge Acanthostrongylophora ingens, along with halicyclamine B (2) as proteasome inhibitors. Compound 1 is the second example found to have a pyridinium ring in the halicyclamine family. Although the relative configuration of 2 was previously determined by X-ray crystallographic analysis, here we determined the absolute configuration of 2 by ECD experiment. Compounds 1 and 2 inhibited the constitutive proteasome as well as the immunoproteasome. The inhibitory activities of 2 were 4- to 10-fold more potent than those of 1.
