Aims: To isolate, characterize and identify bacteriocins from lactic acid bacteria in soil. Methods and Results: Thirty-four acid-producing bacteria were isolated from 87 soil samples. Antibacterial activities were detected, and one strain, L28-1 produced a bacteriocin that was active against some Gram-positive bacteria. L28-1 was identified as Enterococcus durans by 16S rDNA sequence analysis and API50CHL. This bacteriocin did not lose its activity after autoclaving (121°C for 15 min), but was inactivated by protease K. The bacteriocin was purified by hydrophobic column chromatography, and Sep-Pak C 18 . Tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the partially purified bacteriocin contained numerous protein bands. Two bands that displayed antibacterial activities were c. 3AE4 and 2AE5 kDa in size. In this work, the 3AE4-kDa bacteriocin was analysed with N-terminal amino acid and DNA sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis. The results indicated that the 3AE4-kDa bacteriocin of Ent. durans L28-1 is a new natural enterocin variant. Conclusions: Enterococcus durans L28-1 produced a new bacteriocin. Significance and Impact of the Study: This study reports a novel bacteriocin that is produced by Ent. durans that has potential for use as a food preservative.

This study suggests that bacteriocin-producers act effectively as safe biopreservatives and may contribute to the biopreservation in Miso-pastes.

Aims:  To investigate the effects of two prebiotics and trehalose on the production of bacteriocins. Methods and Results:  Four carbohydrates [dextrose, fructo‐oligosaccharides (FOS), raffinose, and trehalose] were used as the sole carbon source in a simple broth. Five bacteriocin‐producing strains of bacteria, including those producing nisin, enteriocin, and other bacteriocins, were used, and their inhibitory activities when grown on each carbohydrate were determined. The inhibitory activity assay was performed using the agar well diffusion method, and Lactobacillus sakei JCM 1157T was used as the indicator strain. Effective enhancement of bacteriocin production was observed with FOS and trehalose incubation. Conclusions:  The results suggest that FOS and trehalose can effectively enhance the production of the five kinds of bacteriocins evaluated in this study. Significance and Impact of the Study:  This study offers useful information for not only a new application of FOS and trehalose, but also the potential improvement of food preservation.

This article describes a microbiological study of lactic acid bacteria involved in the fermentation process of Miso. The bacteria were counted and isolated from Miso during fermentation and, based on the results of traditional phenotypic tests, divided into nine groups. The isolates were identified by biochemical analysis and 16S rRNA sequence analysis. During Miso fermentation, the halophilic bacterium Tetragenococcus halophilus increased moderately. The nonhalophilic strains displayed a complex growth pattern and were identified as Enterococcus faecium, Enterococcus durans, Enterococcus faecalis, Pediococcus acidilactici, Pediococcus pentosaceus, Lactobacillus plantarum and Weissella confusa. The predominant species throughout the fermentation process were T. halophilus, E. faecium and E. durans. Among them, only the strains of E. faecalis and E. durans produced bacteriocins that had an antibacterial effect on B. subtilis, but had none on T. halophilus. The bacteriocin producers appear to play an important role in maintaining normal bacterial flora during Miso fermentation.

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