• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.40-47
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• 2016

This study was conducted to evaluate the possible utility of 3 Aspergillus oryzae strains (designated as SCF-6, SCF-37, and JJSH-1), isolated from Korean traditional fermented materials, as starter cultures in the soybean paste industry. Doenjang (fermented soybean paste) was made with the A. oryzae strains described above, and its quality attributes were analyzed during a 60-day aging period. No significant differences in pH, moisture, or salt content were detected among the doenjang varieties made with the 3 Aspergillus strains. The concentration of amino-nitrogen, an indicator of doenjang aging, increased in each sample during the aging period. After the 60-day aging period, the contents of amino-nitrogen and free amino acid in doenjang made with SCF-6 showed the highest concentrations among the tested doenjang products: 971.6 and 8,064.9 mg%, respectively. Measurements of the color of doenjang showed that lightness and yellowness decreased during the aging period, but redness increased. After the 60-day aging period, the ${\gamma}$-aminobutyric-n-acid (GABA) concentrations in doenjang made with SCF-6 and SCF-37 were 61.3 and 53.7 mg%, respectively. In doenjang samples, aflatoxin was not detected and the concentrations of biogenic amines (histamine and tyramine) were 2.55-5.60 mg/kg and 3.70-5.87 mg/kg, respectively. These results indicated that A. oryzae SCF-6 isolated from traditional fermented foods could be useful as a starter culture in the soybean paste industry.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.316-324
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• 2007

We studied the effects of genistein obtained from glycolysis of genistin, a kind of phytoestrogen present in soybeans, on cell proliferation and type I pN collagen synthesis in normal human dermal fibroblasts(NHDF). Cell proliferation was increased significantly with genistein treatment at 54-year aged NHDF. Genistein increased cell proliferation more strongly in cells form old doner than young doner. The senescence-associated ${\beta}$-galatosidase activity was decreased in NHDF from 77-year old doner with genistein treatment. Type I pN collagen synthesis was increased with genistein treatement in UVA treated and non-treated NHDF. The increasement of collagen synthesis was more effective in aged cells than young cells. Type I pN collagen synthesis was also increased with genistein treatment in collagen matrix culture with NHDF from sun-exposed and non-exposed skin from 54-year old doner. Genistein treatment inhibited MMP-1 synthesis in old NHDF but not in young NHDF. In conclusion, genistein may be a useful agent for preventing intrinsic aging as well as photoaging.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.398-405
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• 2016

The Schizosaccharomyces pombe structural gene encoding bacterioferritin comigratory protein (BCP) was previously cloned using the shuttle vector pRS316 to generate the BCP-overexpressing plasmid pBCP10. The present work aimed to evaluate the thermoresistant properties of BCP against high temperature stress using the plasmid pBCP10. When the S. pombe cells were grown to the early exponential phase and shifted from $30^{\circ}C$ to $37^{\circ}C$ or $42^{\circ}C$, the S. pombe cells harboring pBCP10 grew significantly more at both $37^{\circ}C$ and $42^{\circ}C$ than the vector control cells. After 6 h of the shifting to higher incubation temperatures, they contained the lower reactive oxygen species (ROS) and nitrite content, an index of nitric oxide (NO), than the vector control cells. After the temperature shifts, total glutathione (GSH) content and total superoxide dismutase (SOD) activities were much higher in the S. pombe cells harboring pBCP10 than in the corresponding vector control cells. Taken together, the S. pombe BCP plays a thermoresistant role which might be based upon its ability both to down-regulate ROS and NO levels and to up-regulate antioxidant components, such as total GSH and SOD, and subsequently to maintain thermal stability.

• The Korean Journal of Food And Nutrition
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• v.22 no.3
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• pp.396-401
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• 2009

Microorganisms or their toxins can be transferred to eggs and cause food poisoning in humans. Therefore, this study was conducted to detect microbial contamination of eggs and to identify microorganisms in any contaminated eggs. Four different brands of eggs were collected from hypermarkets in the northern Gyeonggi area. The total bacterial counts on the shells of the eggs varied greatly between brands. In addition, various bacterial species including Klebsiella pneumoniae, Pseudomonas mendocina, Alcaligenes xylosoxidans, Alcaligenes faecalis, and Enterobacter cloacae were identified on eggshells. Furthermore, mean of total bacterial counts of four brands was $3.4{\times}10^4 cfu/m{\ell}$ and E. coli was detected on the eggshell of one brand egg. However, Salmonella was not identified on all brands of collected eggs. We also demonstrated that the E. coli isolated from the eggshell was not pathogenic based on the absence of pathogen-specific gene expression patterns. Taken together, the result of this study indicate that strict quality control and improved distribution controls are required to decrease microbial contamination and improve human health.

• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.727-734
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• 2013

Makgeolli mashes that were brewed using five different commercial nuruks (fermentation starters) were investigated for changes in physicochemistry, microbial diversity, and biogenic amine (BA) production. Mash A brewed with the nuruk (Gaeryang-nuruk) had the highest level of alcohol concentration and the greatest number of yeast cells, whereas mash E had the greatest number of bacterial cells. Only three biogenic amines were detected in the makgeolli mashes: tyramine, putrescine, and cadaverine. Using a PCR-DGGE technique, we observed that mash E had the highest BA production, and had the greatest number of bands on the denaturing gradient gels. We also observed that the numbers of bacterial cells correlated significantly with the putrescine and the total BA content, and that the BA content correlated significantly with the color values (L, a, b). This study shows that the quality of a makgeolli can depend on the type of nuruk. Therefore, we suggest that the quality management of makgeolli should start with the stage of nuruk manufacture.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.15-22
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• 1998

The dnrF gene, responsible for conversion of aklavinone to $\varepsilon$-rhodomycinone via C-11 hydroxylation, was mapped in the daunorubicin gene cluster of Streptomyces peucetius subsp. caesius ATCC 27952, close to drrAB, one of the anthracycline resistance genes. To characterize the enzymatic properties of the aklavinone 11-hydroxylase, the dnrF gene was overexpressed in Escherchia coli. The pET-22(+) plasmid which has the T7 promoter under the control of lacUV5 gene was used for the overexpression of the dnrF gene, and the recombinant plasmid pET213 that contains the dnrF gene linked to the T7 promoter of pET-22b(+) was introduced into the E. coli BL2l. When the expression of the dnrF gene was induced by IPTG at the final concentration of 1 mM, the induced protein could be detected in SDS-PAGE only in insoluble precipitate. The insoluble protein was electroeluted from the gel and used for the preparation of antiserum in mice. Various culture conditions were tested to maximize the expression of the aklavinone 11-hydroxylase in soluble form. The enzymatic activity was checked by the bioconversion experiment, and the protein was confirmed by the SDS-PAGE and the Western blot analysis. From the analysis of the data, it was concluded that the culture induced with IPTG at the final concentration of 0.02 mM at 37$^{\circ}C$ yielded the best productivity of active form of enzyme.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.265-272
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• 2001

The diversity of acid-tolerant epiphytic bacterial communities on deciduous oak tree (Quercus dentate Thunb.) leaves was examined both in the natural forest area with a clean air and in the industrial estate to assess effects of acidic depositions to the phyllosphere using 16S rDNA sequence data. A total of 444 acid-tolerant epiphytic bacterial clones were obtained, resulting in 17 phylotypes by performing a analysis of restriction fragment length polymorphism (RFLP) for PCR-amplified 16S rDNA products. A very low diversity of dominating acid tolerant bacterial communities in both areas was found, just 2 subphyla groups, $\gamma$-Proteobacteria and low-G+C gram-positive bacteria. As tree leaves grow older, diversities of acid-tolerant bacteria on them significantly increased. The community structure of acid-tolerant epiphytic bacteria consisted of Pseudomonas and Enterobacteriaceae groups in the $\gamma$-Proteobacteria subphylum, and Streptococcaceae and Staphylococcus groups in the low-G+C gram-positive bacteria subphylum. The direct influence of acidic depositions on bacterial phylogenetic composition could not be detected especially when higher taxonomic levels such as subphylum, but at narrower or finer levels it could be observed by a detection of Xanthomonadales group belonged to the $\gamma$-Proteobacteria only in the industrial area and of Acetobacteraceae group belonged to the $\alpha$-Proteobacteria. There remains that these specific acid-tolerant epiphytic bacterial groups could be used as indicators for assessing effects of acidic depositions on the phyllosphere.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.209-214
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• 2012

The purpose of this study was to evaluate microbiological contamination of fresh-cut produce salads and raw cabbage toward climate change. Total aerobic bacteria, coliform and Escherichia coli were monitored to get the contamination levels and E. coli O157:H7, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Salmonella spp. to detect pathogens with risk of foodborne disease from samples. Collection of 360 samples (180 fresh-cut produce salads and 180 raw cabbage), including 60 samples from each area after setting 3 areas depending on annual temperature and annual rainfall. As a result, total aerobic bacteria and coliform group were different was performed areas in raw cabbage but there was no difference between areas in fresh-cut produce salads. In addition foodborne pathogens including E. coli were not isolated from fresh-cut produce salads.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.175-183
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• 1998

Yulmoo Mul-kimchi was prepared by fermentation of the mixture of 1 part of leafy radish and 2.75 parts of water. It is thought that during the kimchi fermentation both the biosynthesis and destruction of ascorbic acid occurred at the same time. So the ascorbic acid content in Kimchi broth was strongly influenced by the environment of the processing period. In the present studies, an attempt had been made to elucidate the effect of water quality on the content of ascorbic acid and the population change of microorganism during Mul-kimchi fermentation. Five kinds of water such as tap water, an underground water, one commercially available processed water, distilled water and triply distilled water were examined. Nevertheless there were no differences in the population of microorganism and the pattern of acid formation among the five different kind of waters, a large variation of ascorbic acid content was observed. The ascorbic acid content of Kimchi prepared with triply distilled water showed the highest of 7.2 mg% in contrast to 3.37 mg% in tap water kimchi, and 5.72 mg% in the kimchi using underground water which has relatively high concentration of Ca. These results suggested that pure water free of metal ions might prevent the destruction of ascorbic acid during the fermentation. The considerable amount of ascorbic acid in the Kimchi with underground water might be due to Ca ion in the water.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.640-645
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• 2000

The effect of gamma-irradiation on the quality changes of the grain shape improved Meju was studied. Meju was prepared, irradiated at 0, 5, 10 and 20 kGy, and then stored at $25^{\circ}C$ for six months. The results showed that the fungi and acid producing bacteria were completely eliminated by gamma-irradiation with dose of 10 kGy or higher and the Bacillus was decreased by 5 log cycles with dose of 10 kGy. The $D_{10}$ values of the fungi, Bacillus and acid producing bacteria were 0.79, 2.28 and 1.17 kGy, respectively. Also, the microorganisms that survived irradiation was decreased significantly with the duration of storage period. The $NH_3-nitrogen$, negative factors of quality of Meju, and browning were repressed and the protease activity and pH were not affected by gamma-irradiation. Therefore, it was considered that the Meju treated with gamma-irradiation maintained better quality than that of the control with storage.