The microbial distribution and its predominant lactic acid bacterial flora in traditional fermented sushi

Abstract

　The following results were obtained when we investigated the viable bacterial count, lactic acid bacteria count, gram-negative bacteria count, and yeast count in traditional Japanese fermented sushi, and conducted a microbiological study of the microbiota. For the nine types of fermented sushi, the pH was 3.62±0.01 to 4.75±0.02 and the salt concentration was 1.57±0.06 to 5.90±0.12%. The viable bacterial count was between 4.61±0.11 and 8.86±0.06 log CFU/g and the lactic acid bacteria count was between 5.89±0.02 and 8.99±0.05 log CFU/g. The gram-negative bacteria count ranged below the detection limit and 4.59±0.11 log CFU/g, and the yeast count was below the detection limit and 6.80±0.01 log CFU/g. Although the predominant lactic acid bacterial flora detected in the fermented sushi was lactic acid bacteria of genus Lactobacillus, the characteristic microflora was present depending upon the different raw ingredients and states of fermentation. The findings of this study show that fermented sushi consists of different raw ingredients under different conditions of fermentation, creating a characteristic lactic acid bacterial flora for each food item.