• The Korean Journal of Mycology
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• v.23 no.2 s.73
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• pp.161-175
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• 1995

Meju is a raw material used to make Korean soy sauce (Kanjang) and soybean paste (Doenjang), both of them rich in plant protein. The twenty-nine fungal and a bacterial species were identified from twenty-three traditionally homemade meju cakes. Out of them, only a few species were found to be involved in the actual fermentation process of meju; The other species were contaminants during the improper subprocesses of meju fermentation. The fungal floral successions were observed to be related to two physical and biochemical changes of meju cakes during meju fermentation: drying and heat releasing processes. The zygomycetous fungi were first observed to exist mainly during the first stage. Scopulariopsis brevicaulis was observed to grow on the surface of meju cakes and then to coexist with Bacillus megatrium in the inner part of meju cakes during the second stage. Based on the biochemical tests, the proteases secreted by the different microorganisms were involved in the degradation of soybean proteins with a mutual relationship. Also, zygomycetous fungi were speculated to be important microorganisms for inducing the second stage in the traditional Korean homemade meju.

• KSBB Journal
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• v.20 no.6
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• pp.393-400
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• 2005

Hydrogen($H_2$) as a clean, and renewable energy carrier will be served an important role in the future energy economy. Several biological $H_2$ production processes are known and currently under development, ranging from direct bio-photolysis of water by green algae, indirect bio-photolysis by cyanobacteria including the separated two stage photolysis using the combination of green algae and photosynthetic microorganisms or green algae alone, dark anaerobic fermentation by fermentative bacteria, photo-fermentation by purple bacteria, and water gas shift reaction by photosynthetic or fermentative bacteria. In this paper, biological $H_2$ production processes, that are being explored in fundamental and applied research, are reviewed.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.125-131
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• 2000

Quality characteristics of kochujang prepared with meju, koji and mixture of the two(meju+koji) were investigated during fermentation to improve quality of kochujang. During fermentation of kochujang, moisture content was in the range of $53.4{\sim}66.5%$, salt was $8.3{\sim}10.1%$, crude protein was $8.3{\sim}19.3%$ and pH of kochujang was $4.6{\sim}5.4$. Amino-nitrogen content increased during fermentation and the levels were $230{\sim}270\;mg%$ after 150 days of fermentation. The highest amino-nitrogen content was found in mixed kochujang at the beginning stage of fermentation, but in koji kochujang after 30 days of fermentation. Maximum reducing sugar content was $15.0{\sim}19.5%$ at 60th day of fermentation. The highest amino acid content of kochujang protein was found in meju kochujang followed by koji kochujang at the first stage of fermentation. The content of glutamic acid, a major amino acid was $1.38{\sim}3.66%$ of total amino acid content. High levels of aspartic acid, leucine, arginine, alanine and phenylalanine were found in the kochujangs. Mixed kochujang showed the highest L value among the samples until 30 days of fermentation. After that, the highest L value was found in meju kochujang. The highest degree of redness was observed in meju kochujang until 60 days of fermentation and in koji kochujang during $90{\sim}120$ days of fermentation.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.30-36
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• 2002

To use overproduction muskmelon effectively, muskmelon vinegar was prepared by two stage fermentations of alcohol and acetic acid. In the alcohol fermentation using muskmelon, alcohol content showed maximum value (7.47%) in $17.83^{\circ}Brix$ of initial sugar concentration and 82.65 h of fermentation time. Acetic acid content in alcohol fermentation revealed minimum value (0.46%) in $12.17^{\circ}Brix$ of initial sugar concentration and 60.56 h of fermentation time. The fermentation conditions for minimum residual sugar were $10.02^{\circ}Brix$ of initial sugar concentration and 105.61 h of fermentation time. The optimum conditions predicted for each corresponding physical properties of acetic acid fermentation were 200 rpm (agitation rate), 250 h (fermentation time) in acetic content and 200 rpm, 150 h in residual alcohol content.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.81-88
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• 2015

This study describes a novel strategy to regulate the metabolic flux for lactic acid production in Lactobacillus casei. The ldhL gene encoding _L-lactate dehydrogenase (L-LDH) was overexpressed in L. casei, and a two-stage oxygen supply strategy (TOS) that maintained a medium oxygen supply level during the early fermentation phase, and a low oxygen supply level in the later phase was carried out. As a consequence, a maximum L-LDH activity of 95.6 U/ml was obtained in the recombinant strain, which was over 4-fold higher than that of the initial strain. Under the TOS for L. casei (pMG-ldhL), the maximum lactic acid concentration of 159.6 g/l was obtained in 36 h, corresponding to a 62.8% increase. The results presented here provide a novel way to regulate the metabolic flux of L. casei for lactic acid production in different fermentation stages, which is available to enhance organic acid production in other strains.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.487-490
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• 1991

In this study continuous alcohol fermentation of molasses by the recirculation system has investigated. After cultivation of yeast cells in the YPD medium with increasing the medium concentration from 10 to 183.5 g/l stepwisely, the fermentation medium was replaced by molasses. The maximum cell mass was 25 g/l, and the mean cell mass during the operation was 23.5g/1, which was 3.4 times higher compared with a conventional batch system. The optimum fermentation conditions with feeding molasses of 180 g/l were obtained when the fermentation was carried out at 500 rpm and at the dilution rate of 0.037 $h^{-1}$. Under these conditions we could safely operate the fermentor for 645 h without any trouble. The maximum alcohol productivity was 4.9 g$l\cdot h$ with an alcohol concentration of 53.9 g/l at the dilution rate of 0.091$h^{-1}$.

• Applied Biological Chemistry
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• v.42 no.2
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• pp.111-115
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• 1999

This study was attempted to develop technique of masking the pungent odor of chonggugjang using two-stage fermentation method with mixed pure cultures. Cooked soybeans were fermented with Lactobacilli or Aspergillus oryzae at $38^{\circ}C$ for 36 hrs, and then re-fermented with Bacillus subtilis for 12 hrs. The volatile compounds of chonggugjang were obtained with a SDE(Simultaneous steam Distillation and solvent Extraction) system and the extracts were identified by GC and GC-MS. The experimental results revealed the presence of 35 volatile compounds in control chonggugjang(only Bacillus subtilis inoculation). Among them, the major volatile compounds were 2,5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine and 2-methyl pyrazine. Twenty-nine kinds of volatile compounds were in chonggugjang prepared by two-stage fermentation method with Lactobacilli and Bacillus subtilis(II), and major volatile compounds were identified to be 2,3,5-trimethyl pyrazine and 2,5-dimethyl Pyrazine. In chonggugjang(Asp. oryzae and then Bacillus subtilis inoculation(III)), the contents of hexadecanoic acid and 2-methyl pyrazine were patricularly high and the main components of chonggugjang fermented with rice straw(IV) were 2,5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine etc. In conclusion, the flavor compounds such as 2, 5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine and 2-methyl pyrazine were increased by the inoculation of Lactobacilli or Asp. oryzae, where as unpleasant odor components-butyric acid and valeric acid were decreased. Compared with volatile compounds of chonggugjang made from different soybean cultivars, the flavor compounds (2-methyl pyrazine 2,5-dimethyl pyrazine 2,6-dimethyl pyrazine 2,3-dimethyl pyrazine 2-acetyl pyrazine 2,3,5-trimethyl pyrazine 2-ethyl-3,5-dimethyl pyrazine) of chonggugiang prepared with Sinpaldalkong were high.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.1007-1014
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• 2017

To compare functional Chinese cabbage('Amtak' baechu; F1 hybrid cultivar between Brassica rapa and B. perkinensis, AB) with general Chinese cabbage ('Chunkwang' baechu; general spring cultivar, CB), two kinds of kimchi(ABK and CBK) prepared with AB and CB cultivar were fermented at $10^{\circ}C$ for 10 days. Their fermentative characteristics and anti-proliferative activities against mouse carcinoma cell lines were investigated. General kimchi(CBK) showed mature pH on the $6^{th}$ day of fermentation, whereas functional kimchi(ABK) reached pH on the $9^{th}$ day. CBK also exhibited acidity of mature stage on the $6^{th}$ day, but ABK reached mature acidity on the $9^{th}$ day. Although ABK and CBK were salted in the same condition, ABK had lower salinity than CBK, throughout the fermentation time. The highest total bacterial and lactic bacterial counts of CBK showed on the $8^{th}$ day of fermentation, but ABK showed the highest total bacterial and lactic bacterial counts on the $10^{th}$ day. The texture of ABK was harder than CBK for fermentation time. This seems to be corrleated with the slower fermentation rate of ABK. ABK showed significantly higher anti-proliferative activity (54.6% cell viability of control) in B16BL6 at $1,000{\mu}g/mL$. ABK was also higher in anti-proliferative activity than CBK throughout the fermentation time. However, there was no significant difference in the anti-proliferative activity of ABK between the fermentation times. In conclusion, fermentation of ABK showed a better texture, due to the slow fermentation rate and more anti-proliferative activity against mouse carcinoma cell line than those of CBK.

• Microbiology and Biotechnology Letters
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• v.43 no.4
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• pp.350-356
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• 2015

There have been several studies on role of hormesis with light stimulation, however, the influence of light on fermentation is still poorly understood. In this study the relationship between LED (light emitting diode) hormesis and ethanol fermentation for Muscat bailey A wine was investigated. Two LEDs, one blue ($453{\pm}4nm$) and one green ($522{\pm}3nm$), were used. Both LED groups showed an inhibited production of lactic acid. The blue LED stimulated the growth of the yeast in early stage of the fermentation. Polyphenolic compounds and their antioxidant abilities were significantly increased by the green LED. These results demonstrate that LED irradiation must bring about hormesis and affect the growth rate of yeast in the early stage of the fermentation, and the contents of phytochemicals during fermentation. These findings indicate the possible application of LED hormesis for the wine fermentation. Further studies are needed to understand how LED irradiation induces hormesis effects during the fermentation process.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.248-254
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• 1992

The initial growth of Clostridium acetobutylicum was not inhibited by 1 atm of H$_2$ while H$_2$ reduced glucose consumption in a solventogenic culture of a phosphate limited 2-stage chemostat. Under 1 atm of H$_2$, a solventogenic culture consumed hydrogen, but an acidogenic culture produced hydrogen. H$_2$ consumption by the solventogenic culture was enhanced by the addition of 5 mM neutral red, an artificial electron carrier with a redox potential of -325 mV. Hydrogenase activity, measured in both directions of production and consumption, showed that activity coupled with methyl viologen is higher in an acidogenic culture than in a solventogenic culture, and that the two cultures have similar activities for methylene blue reduction. The solventogenic culture showed a higher activity coupled with neutral red than the acidogenic culture. From these results, it is hypothesized that hydrogen producing hydrogenase activity is high during the acidogenic phase, and decreases as solventogenesis starts, and that the solventogenic culture produces a second hydrogenase which uses an electron carrier other than ferredoxin. This hypothesis was supported by the fact that enzyme activities involved in electron flow can be coupled to neutral red, indepedent of ferredoxin, and that neutral red addition to the fermentation system increased butanol yield, with a decrease in production of less reduced fermentation products, and $H^2$.