Physical and genetic map of the Weissella paramesenteroides DSMZ 20288T chromosome and characterization of different rrn operons by ITS analysis

A potent probiotic strain from cheddar cheese

A lactic acid bacteria Leuconostoc paramesenteroides was isolated and characterized from cheddar cheese and was adapted to grow at low pH (2.0) and high bile salt concentration (2%) by sequential sub-culturing so that it can survive the extreme environmental condition of gut. Cell hydrophobicity assay shows the maximum adherence of the culture to toluene (46.11%). Adhesion ability was confirmed by in vitro assay using rat intestinal epithelial layer. The culture has an antimicrobial activity against food borne pathogens and is vancomycin sensitive. The culture shows a β-galactosidase activity of 3.42 μM/mg protein, which indicates the ability of the culture to hydrolyze lactose for easy absorption. All these properties determine the ability of the culture to be used as a probiotic.

Application of quantitative real-time PCR for enumeration of total bacterial, archaeal, and yeast populations in kimchi

Kimchi is a Korean traditional fermented food made of brined vegetables, with a variety of spices. Various microorganisms are associated with the kimchi fermentation process. This study was undertaken in order to apply quantitative real-time PCR targeting the 16S and 26S rRNA genes for the investigation of dynamics of bacterial, archaeal, and yeast communities during fermentation of various types of kimchi. Although the total bacterial and archaeal rRNA gene copy numbers increased during kimchi fermentation, the number of yeasts was not significantly altered. In 1 ng of bulk DNA, the mean number of rRNA gene copies for all strains of bacteria was 5.45 x 10(6) which was 360 and 50 times greater than those for archaea and yeast, respectively. The total gene copy number for each group of microorganisms differed among the different types of kimchi, although the relative ratios among them were similar. The common dominance of bacteria in the whole microbial communities of various types of kimchi suggests that bacteria play a principal role in the kimchi fermentation process.

Genome diversity in the genera Fructobacillus, Leuconostoc and Weissella determined by physical and genetic mapping

Pulsed-field gel electrophoresis analysis of chromosomal single and double restriction profiles of 17 strains belonging to three genera of ‘Leuconostocaceae’ was done, resulting in physical and genetic maps for three Fructobacillus, six Leuconostoc and four Weissella strains. AscI, I-CeuI, NotI and SfiI restriction enzymes were used together with Southern hybridization of selected probes to provide an assessment of genomic organization in different species. Estimated genome sizes varied from 1408 kb to 1547 kb in Fructobacillus, from 1644 kb to 2133 kb in Leuconostoc and from 1371 kb to 2197 kb in Weissella. Other genomic characteristics of interest were analysed, such as oriC and terC localization and rrn operon organization. The latter seems markedly different in Weissella, in both number and disposition in the chromosome. Comparisons of intra- and intergeneric features are discussed in the light of chromosome rearrangements and genomic evolution.