Transition and regulation mechanism of bacterial biota in Kishu saba-narezushi (mackerel narezushi) during its fermentation step

The transition of the bacterial biota of Kishu saba-narezushi (mackerel-narezushi) in the Hidaka region of Wakayama prefecture, Japan, was analyzed using amplicon sequencing based on the V3–V4 variable region of the 16S rRNA gene. In the non-fermented sample (0 day), the major genus with the highest abundance ratio was Staphylococcus. In the early stage (fermentation for 2 days), however, the genus Lactococcus became a dominant species, and in the later stage (fermentation for 5 days), the abundance ratio of the genus Lactobacillus increased significantly. Lactococcus lactis strains isolated from the narezushi samples had the ability to suppress the growth of not only Staphylococcus genera but also Lactobacillus. Moreover, the isolates produced a bacteriocin, which was identified as nisin Z. On the basis of these results, it is concluded that L. lactis plays an important role in preparing the fermentation conditions of Kishu saba-narezushi in the early stage by suppressing unwanted microorganisms using lactic acid and nisin Z.