Evaluation of the Biogenic Amine-production Ability of Lactic Acid Bacteria Isolated from Tofu-misozuke

Tofu-misozuke is a traditional fermented food in Japan, and contains biogenic amines that function as neurotransmitters, but are toxic when consumed at high levels. Analysis of the amine production of bacterial communities is important for controlling the amine content in fermented foods. We investigated the bacterial community and biogenic amine content of tofu-misozuke. The lactic acid bacteria (LAB) ratio in the community and tyramine content were highly related. LAB were isolated to identify the biogenic amine-producing species. Isolated strains from tofu-misozuke were identified, and their tyramine formation potential was evaluated by PCR detection of the tyrosine decarboxylase gene and by cultivation tests. We detected three tyramine-producing bacteria, Enterococcus faecium, Weissella viridescens, and Lactobacillus curvatus, in tofu-misozuke.