The 21 Kimchi samples collected by a contest for the best Kimchi homemaker in Jeonju were analysed to find major microbial composition and the correlation between sensory scores and the microbial properties, which include total microbial numbers, dominant strain number, subdominant strain number, yeast strain numbers, and floral diversity. The most common microbial composition of the Kimchi samples was Leuconostoc mesenteroides as dominant strain, and Lactobacillus sakei as subdominant strain, the pattern of which was also observed in all three Kimchi samples with the highest sensory scores, but not in all three Kimchi samples with the lowest sensory scores. However none of the other examined properties showed any significant correlation to sensory scores. This result means that the taste of fermented Kimchi depends mainly on the composition of bacterial species and that of Leuconostoc mesenteroides as dominant strain and Lactobacillus sakei as subdominant strain is the best for good taste. Yeast strains were found in the range of 3.8～4.6 logCFU/g from 8 Kimchi samples and all the strains were identified to be Saccharomyces servazzii. However, fungi were not detected from any of the Kimchi. samples.

This research was carried out in order to discover acid-forming bacteria during fermentation of Makgeolli, as Makgeolli loses its commercial value due to overproduced acidic materials. In Makgeolli kept at 25℃, a sudden increase of acidity as well as the disappearance of yeast cells occurred at day 6, whereas the total cell count and bacterial type remained unchanged; the result implies that a succession of bacterial types, including acid forming bacteria, occurred. Two acidforming bacteria were isolated from acidified Makgeolli and were identified as Acetobacter pasteurianus and Lactobacillus casei. When fresh and heat-treated Makgeolli were inoculated with Acetobacter pasteurianus and/or Lactobacillus casei, the greatest amount of acid was formed in Makgeolli inoculated with Acetobacter pasteurianus and Lactobacillus casei and also in Makgeolli with Acetobacter pasteurianus alone. This result indicates that Acetobacter pasteurianus is the main acidifier; furthermore, it shows the synergy effect in acid formation with Lactobacillus casei.

The cholera toxin B subunit (CTB), which consists of five identical polypeptides and adopts a pentameric structure, has been shown to bind to the GM1-gangliosides at the cellular surface. Recombinant CTB has attracted much attention due to its non-toxicity and potential as a strong immunogenic antigen and immuno adjuvant for both system and mucosal immune responses. In this study, CTB was expressed in p~ÅÅÜ~êçãóÅÉë=ÅÉêÉîáëá~É and the resulting recombinant CTB was extensively characterized. PCR and back-transformation into bK=Åçäá confirmed the presence of the CTB gene-containing plasmid in the transformants and northern analysis showed the presence of the CTB-specific transcript. Western blot analysis of the yeast-derived protein extract showed the presence of CTB with mobility similar to purified CTB from sáÄêáç=ÅÜçäÉê~É suggesting that the expressed CTB assembled into the desired pentameric form. Quantitative ELISA revealed that the recombinant CTB comprised approximately 0.5~1.3% of the total cell-free extract. In addition, 0.5~2 mg of CTB protein per liter of cultured media was detected 1 day, at the earliest after cultivation. The GM1-ganglioside enzyme-linked immunosorbent assay (GM1-ELISA) confirmed that the yeast-derived CTB bound specifically to the GM1-ganglioside receptor, indicating that it retained its native function and pentameric form, which is required for binding to intestinal epithelial cell membrane glycolipid receptors. In addition to the development of a yeast-derived edible vaccine against cholera, this study regarding the expression and assembly of recombinant CTB into biologically active oligomers in recombinant pK=ÅÉêÉîáëá~É enables the efficient production of a GRAS microorganism-based adjuvant, as well as the development of carriers for foreign vaccine molecules. © KSBB hÉóïçêÇëW=Vibrio choleraeI=ÅÜçäÉê~=íçñáå=_=ëìÄìåáíI=djNJbifp^I=Saccharomyces cerevisiae= = = = =

This research was carried out to find herbal preservatives for Makgeolli, as Makgeolli loses its commercial value due to overproduced acidic materials. When Makgeolli was kept at 25℃ to find the changes in acidity, total microbial cell number, yeast cell number, and bacterial species variety, a sudden increase of acidity as well as the disappearance of yeast cells occurred at day 6, and Makgeolli was changed to complete off-flavor. Acetobacter pasteurianus is the main acidifier in Makgeolli and shows a synergy effect in acid formation when cultured in combination with Lactobacillus casei. Among 12 herbs, the ethanol extract of Sutellaria baicalensis showed antimicrobial activity against A. pasteurianus, whereas the ethanol extract of Coptidis rhizoma showed antimicrobial activity against L. casei. Makgeolli added with Sutellaria baicalensis extracts demonstrated a lower acidity than that with Coptidis rhizoma extracts, which indicates that the inhibition of an acetic acid former is more important than that of a lactic acid former in Makgeolli preservation. Sutellaria baicalensis extracts prolonged the shelf life of Makgeolli by 1～2 weeks at a minimal inhibitory concentration (0.63 ㎎/㎖) during storage at 10℃.

A previous study has demonstrated that both interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) were needed to induce the production of nitric oxide (NO) in BNL CL.2 cells, murine embryonic liver cells. We here demonstrate that when BNL CL.2 cells were cultured with serum-free medium, they were induced to produce NO by the stimulation of IFN-gamma alone. BNL CL.2 cells were cultured with serum-free or serum-containing medium for 1-3 days and then stimulated to synthesize NO by IFN-gamma. Surprisingly, only serum-starved cells showed significant amount of nitrite accumulation and iNOS protein expression in response to IFN-gamma in dose- and time-dependent manners, but serum-supplied cells did not. When the cells were stimulated with IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), or LPS in combinations, only the combination of IFN-gamma and LPS produced more NO than that produced by IFN-gamma alone. The production of NO by the cells stimulated with IFN-gamma or IFN-gamma plus LPS was blocked by the addition of N(G)-monomethyl-L-arginine (N(G)MMA), a NO synthesis inhibitor. To address the intracellular signal pathway responsible for the production of NO by the cells stimulated with IFN-gamma aloneor IFN-gamma plus LPS, we examined the effects of several protein kinase inhibitors on the production of NO from the cells. The production of NO was significantly inhibited by protein tyrosine kinase (PTK) inhibitors, genistein and herbimycin A, but not by protein kinase A or C inhibitors. These results suggest that the deprivation of serum from BNL CL.2 cell culture medium might prime the cells to induce NO synthesis when the cells are triggered by IFN-gamma and the involvement of PTK signal transduction pathway in the expression of inducible NO synthase gene in murine hepatoma cells.