• Applied Biological Chemistry
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• v.14 no.2
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• pp.137-148
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• 1971

Studies were carried out to investigate the main fermentation microorganisms and their flora changes during Korean native soy-sauce fermentation. Korean native Maeju loaves collected from 5 Do's were separated into surface and inner parts. Four different soy-sauces-the surface part Maeju fermented soy-sauce, the inner part, the surface and inner part combined Maeju fermented soy-sauce, and the semi-Japanese type soy-sauce were fermented and the changes of fermentation microorganism flora and the various chemical components during the period of their fermentations were studied. Besides, 14 home-made soy-sauces collected from 14 different places all over Korea were examined in comparison with the laboratory soy-sauces and to determine the characteristics of Korean native soy-sauce. The results were as follows: 1. The main microorganisms in Korean native soy-sauce fermentation were determined as; Aerobic bacteria: Bacillus subtilis, Bacillus pumilus Lactic acid bacteria: Pediococcus halophilus, Leuconostoc mesenteroides Yeasts: Torulopsis datila, Saccharomyces rouxii 2. Microflora changes during Korean native soy-sauce fermentation were as follows; Aerobic bacteria increased until the 2nd week of fermentation and then gradually decreased. The lactic acid bacteria increased until the 3rd week, after which decreased. When the lactic acid fermentation lowered the pH value to below the 5.4, yeasts were able to grow and participate the fermentation. As the production of organic acids amounted, to a certain height, the growth of all microorganisms lead to the period of decline or death at about the 2nd month of fermentation. After boiling of soy-sauce most microorganisms except a few of Bacillus sp. disappeared. Occosionally yeasts and lactic acid bacteria survived depending upon the composition of soy-sauce. 3. Changes of general chemical components influencing the microflora were investigated for the period of Korean native soy-sauce fermentation. Tetal acidity, salt concentration and total nitrogen were increasing steadily over the entire period of fermentation. pH values were dropping to a certain degree of about 4.5. Salt concentration and pH value seemed to be the important factors influencing the microflora. 4. The microflora were influenced by chemical components of soy-sauce. Aerobic bacteria were able to survive in all soy-sauce as they made spores. Growth of lactic acid bacteria was inhited at 23-26% of salt concentration and pH 4.8. Soy-sauce yeasts started to grow only at pH below 5.4 and seemed to be inhibited at around 26% of salt concentration under pH 4.5-4.7. 5. The open kettle boiling of soy-sauce, the characteristic process of Korean native soy-sauce manufacturing, was effective to sterilize microorganisms, increase the salt concentration, and coagulate proteins. 6. The average viable cell counts of microorganism found in collected samples of home-made Korean native soy-sauces were; Aerobic bacteria: $53{\times}10^2\;cell/ml$ Lactic acid bacteria: 34 cell/ml Yeasts: 14 cell/ml The average values of chemical compositions of samples of home-made Korean native soy-sauce were; Salt concentration: 28.9% pH value: 4.79 Total acidity(lactic acid): 0.91g/100ml Total nitrogen: 1.09g/100ml

• Journal of Microbiology
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• v.42 no.4
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• pp.285-291
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• 2004

The soil bacterial community and some inoculated bacteria were monitored to assess the microbial responses to prescribed fire in their microcosm. An acridine orange direct count of the bacteria in the unburned control soil were maintained at a relatively stable level $(2.0\~2.7\times10^9\;cells/g^{-1}{\cdot}soil)$ during the 180 day study period. The number of bacteria in the surface soil was decreased by fire, but was restored after 3 months. Inoculation of some bacteria increased the number of inoculated bacteria sev­eral times and these elevated levels lasted several months. The ratios of eubacteria detected by a flu­orescent in situ hybridization (FISH) method to direct bacterial count were in the range of $60\~80\%$ during the study period, with the exception of some lower values at the beginning, but there were no definite differences between the burned and unburned soils or the inoculated and uninoculated soils. In the unburned control soil, the ratios of $\alpha-,\beta-\;and\;\gamma-subgroups$ of the proteobacteria, Cytophaga-Fla­vobacterium and other eubacteria groups to that of the entire eubacteria were 13.7, 31.7, 17.1, 16.8 and $20.8\%,$ respectively, at time 0. The overall change on the patterns of the ratios of the 5 subgroups of eubacteria in the uninoculated burned and inoculated soils were similar to those of the unburned con­trol soil, with the exception of some minor variations during the initial period. The proportions of each group of eubacteria became similar in the different microcosms after 6 months, which may indicate the recovery of the original soil microbial community structure after fire or the inoculation of some bac­teria. The populations of Azotobacter vinelandii, Bacillus megaterium and Pseudomonas fluorescens, which had been inoculated to enhance the microbial activities, and monitored by FISH method, showed similar changes in the microcosms, and maintained high levels for several months.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.328-335
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• 2013

As a result of conducting a cultural experiment of tomato using chicken feather protein hydrolysate (CPH) which was mass produced by keratin protein degrading bacterium Chryseobacterium sp. FBF-7 (KACC 91463P), we found that the stem and the root of tomato showed significant improvement in growth. For the purpose of phylogenic interpretation, a comparison was drawn between the effect of CPH, a treated CPH and untreated, on the changes of bacterial populations by 454 pyrosequencing based on 16S rRNA gene sequences. Tomato rhizosphere soil untreated with CPH (NCPH) showed 6.54 Shannon index from 3,281 sequence reads, and the rhizosphere soil treated with CPH (TCPH) showed 6.33 Shannon index from 2,167 sequence reads, displaying that it does not affect the diversity. Bacterial populations were composed of 19 phyla in the rhizosphere soil, and the phylum Proteobacteria occupied 40% of total bacterial populations. Bradyrhizobium, Agromonas, Nitrobacter, and Afipia (BANA group) which belong to Bradyrhizobiaceae were abundant and commonly detected in both the treated and untreated soils, suggesting the dominance of bacterial group in rhizosphere soil. The results obtained showed that CPH treatment does not affect the indigenous bacterial populations present in the rhizosphere soil.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.353-359
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• 2013

The objectives of this study were to investigate effectiveness of the Compressed Air Jet (CAJ) System for cleaning up shorelines contaminated with crude oils and to examine effects of the system on total petroleum hydrocarbon (TPH) removal and microbial community changes before and after remediation of the oil-contaminated shorelines. These data will lead to better understanding of optimized remediation process. About 66% of TPH reduction was observed when the contaminated site was treated with the CAJ System 2, 3, 4, and 5 times. This treatment system was more efficient than the seawater pumping system under similar treatment conditions (by 40%). By the way, little oil degrader communities were observed despite a potential function of the air jet system to stimulate aerobic oil degraders. The apparent low population density of the oil degraders might be as a result of low concentration of TPH as a carbon source and limiting nutrients such as nitrogen and phosphorus. It was proposed that the CAJ System would contribute significantly to removal of residual oils on the shorelines in combination with addition of these limiting nutrients.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.391-397
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• 2013

Changes in ${\beta}$-glycosidase activity, total phenolic and isoflavone contents, and antioxidant activities during the fermentation of Korean black soybeans (Seoritae and Seomoktae) fermented food cheonggukjang by the potential probiotic Bacillus subtilis CSY191 were investigated. The levels of total phenolic and isoflavone-malonylglycoside and -aglycone contents increased, while 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity and ferric reducing/antioxidant power (FRAP) increased, but the isoflavone-glycoside contents decreased after cheonggukjang fermentation. The content of antioxidant compounds, including isoflavone-aglycones and -malonylglycosides, was increased by fermenting-processing, whereas the content of isoflavone-glycosides was decreased in the fermented soybeans. In particular, the Seoritae soybean fermented at 3 $7^{\circ}C$ for 48 h displayed the highest antioxidant activities, compared to those of the Seomoktae soybean and the fermented. The highest levels of daidzein, glycitein, and genistein were present at concentrations of 253.0 ${\mu}g/g$, 72.5 ${\mu}g/g$, and 114.1 ${\mu}g/g$ after 48 h of Seoritae soybean fermentation. From those results, we suggest that the high antioxidant activity of cheonggukjang of black soybeans might be related to the markedly higher levels of total phenolic and isoflavone-aglycone and -malonylglycoside contents achieved during fermentation.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.120-127
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• 2005

Electron beam irradiation was applied to examine the microbial growth and qualities of vacuum-packaged chicken breasts. Chicken breast samples were irradiated at dose of 2, 4, 8, 12, and 16 kGy, respectively. After irradiation, chicken breast samples were individually vacuum-packaged and stored at $4^{\circ}C$. Microbiological change of irradiated vacuum-packaged chicken breasts showed that populations of total bacteria, yeast and mold, total coliform, and salmonella spp. in chicken breasts were significantly reduced with increasing irradiation dose. The pH values of vacuum-packaged chicken breasts were not significantly changed among treatments. Lipid oxidation measurements showed that TBARS values of vacuum-packaged chicken breasts increased with increase of irradiation dose, and gradually increased during storage. Color measurements showed that irradiation reduced Hunter a value of vacuum-packaged chicken breasts with increasing irradiation dose. However, Hunter L and b values of vacuum-packaged chicken breasts were not significantly altered among treatments. Sensory quality results of vacuum-packaged chicken breasts showed that there were no significant changes among the samples irradiated. These results indicate that irradiation can be used to improve the microbial safety and qualities of poultry products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.1
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• pp.83-88
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• 2013

To improve kimchi qualities, Ecklonia (E.) cava of 5%, 15% or 25% were added and the qualities investigated by measuring changes in physicochemical, microbiological, and sensory characteristics during fermentation at $5^{\circ}C$. The pH of kimchi with E. cava added decreased and acidity increased. The number of Leuconostoc sp. in kimchi reached its maximum at the optimum fermenting stage, the $16^{th}$ day in control kimchi and the $20^{th}$ day in the kimchi added E. cava. The optimum fermenting stage of the kimchi was retarded due to adding the E. cava. The reducing sugar contents was highest in kimchi with 25% E. cava during the early stage of fermentation. According to Hunter's color values, the lightness of the kimchi with E. cava added decreased during fermentation, while the redness increased as fermentation proceeded. The sensory scores for overall acceptance, taste, texture and appearance were highest in kimchi with 15% E. cava.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.176-180
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• 1989

There are three pseudourdine ($Psi$)bases in the E. coli $tRNA^{phe}$ In order to study the function of the pseudouridine bases in the $tRNA^{phe}$, changes of bases $tRNA^{phe}$ gene to other bases were undertaken by the site-specific mutagenesis. Site-specific mutagenesis of T in the pheW gene, a $tRNA^{phe}$ gene of E. coli, corresponding to the baseat the No.32 position to C and also T corresponding to the base at the No.39 position to C were performed using Kunkel's uracil-containing template method. Identification of mutants were undertaken by the KNA sequencing techniques of the mutated pheW genes and activities of the mutated pheW genes complementing to E. coli NP37 mutant($pheS^{-ts}$) using the recombinant plasmid containing the mutated genes. Neither NP37 harboring pheW gene mutated at No.32 position nor NP37 harboring pheW gene mutated at No.39 position can be grown at non-permissive temperature. The result means that both mutated pheW genes can not complement to E. coli NP37, and that the pseudouridine bases are essential to the activity of the E. coli $tRNA^{phe}$ in vivo.

• Korean Journal of Microbiology
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• v.37 no.3
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• pp.234-238
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• 2001

For the comparison of fermentation pattern of leek kimci with chinese cabbage kimchi, the changes of total viable cell number, Leuconostoc sp. bacteria, Lactobacillus sp. bacteria, pH and total sugar content of twotypes kimchies were investigated during fermentation at $20^{\circ}C$ and $10^{\circ}C$. In chinese cabbage kimchi at $20^{\circ}C$ fermentaion, the numbers of total viable cell, Leuconostoc sp. bacteria and Lactobacillus sp. bacteria reachedthe maximum level on 2nd day and reduced slowly. But in leek kimchi, the maximum numbers of total via-ble cells, Leuconostoc sp. bacteria and Lactobacillus sp. bacteria were obtained after 3 days fermentation,and the cell number of Lactobacillus sp. maintained at the maximum level oyer 15 days. At $10^{\circ}C$ fer-mentation, in both kimchies, the viable cell number of lactic acid bacteria more slowly increased anddecreased than at $20^{\circ}C$. The pH of chinese cabbage kimchi was 4.2 on 3rd day (optimal ripening phase) andmere decreased to 3.5 after 5 days, but in leek kimci the pH 4.2 could be reached after 10 days at $20^{\circ}C$. At $10^{\circ}C$, the optimal ripening pH 4.2 of chinese cabbage kimchi was reached after 6 days, but in leek kimchieven though after 24 days, the pH was maintained oyer 4.3. The total sugar contents of chinese cabbage him-chi and leek kimci were decreased continuously during fermentation. From these results, we know that thefermentation of leek kimchi proceed more slowly than chinese cabbage kimchi by the retardation of lacticacid bacteria growing in leek kimchi.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.169-174
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• 1998

To define the structure and diversity of bacterial communities in the aqutic ecosystem, Lake Soyang, the largest artificial reservoir in Korea, a new method, fluorescent in situ hybridization was applied. This technique relies on the specific hybridization of the nucleic acid probes to the naturally amplified intracellular rRNA. By this method, the bacterial community composition of Lake Soyang and bacterial numbers belong to eubacteria, proteobacteria and Cytophaga-Flavobacterium group were estimated. Total bacterial numbers ranged from $0.3{\times}10^6{\sim}2.0{\times}10^6cells{\cdot}ml^{-1}$, and vertical profile of total bacteria showed the peak at 2 and 5 m depths. The ratio of eubacteria to total bacteria were 22~100% and varied with depth and season. The percentage of Proteobacteria ${\alpha}$-group ranged 2.6~66.7%, ${\beta}$-group 4.5~53.5%, ${\gamma}$-group 4.6~76.7% and Cytophaga-Flavobacterium group 2.1~35.9%. Also, bacteria] community had spatial and temporal characteristics. The dominant groups were ${\beta}$-group in winter, ${\gamma}$-group in spring and early summer and ${\alpha}$-group in summer.