Pyrosequencing survey of the microbial diversity of ‘narezushi’, an archetype of modern Japanese sushi

Abstract

This study aimed to analyse microbiota of the fermented food 'narezushi', an archetype of modern Japanese sushi. The pyrosequencing technique was used to analyse sequences of 16S ribosomal DNA contained in six narezushi products. The V1-V2 regions of the 16S ribosomal DNA were amplified from different narezushi products using PCR, and approximately 120,000 sequences were phylogenetically assigned at the genus level, using the Ribosomal Database Project classifier. In all samples, the microbial populations consisted of more than 90% Lactobacillales, mainly Lactobacillus or Pediococcus, reflecting their crucial role in narezushi fermentation. There were more than 700 operational taxonomy units in all samples, with Shannon-Wiener index varying from 1.69 to 2.60. The microbiota of all narezushi products were shown to consist largely of Lactobacillales populations. Interestingly, different species were found to be dominant in each product. This study provides an insight into the bacterial composition of fermented fish-based foods, which are consumed worldwide. Significant differences in the dominant species were observed between products, possibly because of the starter-free production process.