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Widespread distribution of the bacteriocin-producing lactic acid cocci in Miso-paste products
T Onda1, F Yanagida, T Uchimura
1Food/Brewing section, The Yamanashi Industrial Technology Center, Japan. takumi@yitc.go.jp
Aims:
A survey was conducted on the ecological distribution of bacteriocin-producing lactic acid bacteria in Miso-pastes, a typical fermented food in Japan. METHODS AND RESULTS Nine Miso-pastes were sampled for isolation of bacteriocin-producers. Almost all isolated enterococcal strains produced bacteriocins but no isolated tetragenococci did so. The bacteriocin-producing isolates were divided into nine groups by phenotypic tests. As the phenotypic characters were highly diverse, these strains could not be identified to species level on the basis of their phenotypes. The nine representative strains from each group were identified by 16S rRNA analysis. These bacteriocin-producers with one exception (Lactococcus sp.) were identified as strains of the Enterococcus faecium 'species group'. The bacteriocins of the nine strains were classified into five types according to their antibacterial spectral patterns and their SDS-PAGE profiles. The bacteriocins inhibited undesirable bacteria in Miso-pastes, such as Bacillus subtilis, but did not inhibit the useful Tetragenococcus halophila.
Conclusions:
The bacteriocin-producing lactic acid cocci were widespread at high frequencies in Miso-pastes. They were considered to play an important role in preventing the growth of undesirable bacteria.
Significance And Impact Of The Study:
This study suggests that bacteriocin-producers act effectively as safe biopreservatives and may contribute to the biopreservation in Miso-pastes.
Insights
Bacteriocin-producing lactic acid bacteria, primarily Enterococcus faecium, are common in Japanese Miso-paste. These microbes effectively inhibit spoilage bacteria, acting as natural biopreservatives.
Area of Science:
- Food Microbiology
- Fermentation Science
- Applied Microbiology
Background:
- Miso-paste, a traditional Japanese fermented food, relies on microbial activity for its unique flavor and preservation.
- Understanding the ecological distribution and function of lactic acid bacteria (LAB) in Miso is crucial for ensuring food safety and quality.
Purpose of the Study:
- To investigate the ecological distribution of bacteriocin-producing LAB in Miso-pastes.
- To identify and characterize bacteriocins produced by these LAB and assess their potential as biopreservatives.
Main Methods:
- Sampling and isolation of bacteriocin-producing LAB from nine Miso-paste samples.
- Phenotypic characterization and 16S rRNA gene sequencing for bacterial identification.
- Classification of bacteriocins based on antibacterial spectra and SDS-PAGE analysis.
Main Results:
- Bacteriocin-producing LAB, predominantly Enterococcus faecium strains, were frequently isolated from Miso-paste.
- Bacteriocins produced inhibited undesirable bacteria like Bacillus subtilis but not beneficial Tetragenococcus halophila.
- Five distinct types of bacteriocins were identified based on their characteristics.
Conclusions:
- Bacteriocin-producing LAB are widespread and abundant in Miso-paste, playing a significant role in controlling spoilage microorganisms.
- These bacteriocin-producers demonstrate potential as safe and effective biopreservatives for Miso-paste.