Microorganisms involved in the preparation of “Sushiko,” a fermented food produced in Tsugaru, Aomori, Japan

Abstract

 Sushiko is a fermented sushi (Narezushi) prepared in Tsugaru area, Aomori, Japan. Here, microorganisms, particularly lactic acid bacteria and yeast, which are involved in the preparation of Sushiko, were investigated. Lactiplantibacillus plantarum and Latilactobacillus sakei were isolated from Sushiko as lactic acid bacteria, and Kazachstania servazzii and Wickerhamomyces anomalus were isolated as yeast. The composition of these species varied according to the season in which they were produced. L. plantarum accounted for 92 %–95 % of bacterial flora of Sushiko produced in August. And the fungal flora of Sushiko mainly consisted of K. servazzii and W. anomalus. K. servazzii and W. anomalus accounted for 44% and 54.8% of the fungal flora, respectively. In Sushiko stored at 4°C for 1 month, the dominant species of yeast was K. servazzii, accounting for 84.1 % of the fungal flora. Overall, the microorganisms involved in preparing Sushiko vary depending on the season in which it is prepared, resulting in variations in flavor. Additionally, chilled storage changes the flavor due to the replacement of the dominant yeast.