• Preventive Nutrition and Food Science
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• v.6 no.1
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• pp.79-81
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• 2001

Deoxynucleoside kinases exist as heterodimeric pairs specific for deoxyadenosine/deoxyguanosine kinase (dAK/dGK) and deoxyadenosine/deoxycytidine kinase (dAK/dCK). The aspartic acid-84 in dGK was mutated to alanine, asparagine and glutamic acid by site-directed mutagenesis. The mutation resulted in a drastic decease in dGK activity compared to the unmodified cloned enzyme while it increased production of dAK activity. The mutated dak/dgk genes, which synthesize tandem deoxyadenosine/deoxyguanosine kinase, were inserted back to the Lactobacillus acidophilus and Lactococcus lactis by electroporation to determine the effect of site-directed mutation of he enzymes on the microbial growth. However, no significant change was observed in cell growth and lactic acid production between wild type and mutant lactic acid bacteria.

• Korean Journal of Food Science and Technology
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• v.52 no.1
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• pp.94-102
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• 2020

Brown rice Makgeolli was brewed by using the Saccharomyces cerevisiae strain SRCM102596 under different fermentation conditions: temperatures at 20 and 25℃ and Nuruk ratios of 5, 10, and 15%. There were no significant differences in the pH and total acidity between samples. The alcohol content at the different nuruk ratios varied significantly by the days in the fermentation process. The major free sugars were maltose, glucose, and fructose, and they gradually reduced with fermentation. The major organic acids in the brown rice Makgeolli were oxalic acid, citric acid, malic acid, succinic acid, and acetic acid. The lactic acid content increased with the number of days in the fermentation process. Among the 24 different free amino acid contents identified, the total free amino acid content of, especially, threonine, serine, and alanine were high in the brown rice Makgeolli, at 20℃ and nuruk ratio of 10%.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.7
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• pp.1103-1112
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• 2020

Objective: To measure whether a microbial additive could effectively improve the fermentation quality of delayed-sealing (DS) silage, we studied the effects of inoculants of lactic acid bacteria (LAB) and cellulase enzyme on microbial populations, ensiling characteristics, and spoilage loss of DS silage of Napier grass in Africa. Methods: Quick-sealing (QS) and DS silages were prepared with and without LAB (Lactobacillus plantarum) inoculant, cellulase enzymes, and their combination. The QS material was directly chopped and packed into a bunker silo. The DS material was packed into the silo with a delay of 24 h from harvest. Results: In the QS silage, LAB was dominant in the microbial population and produced large amounts of lactic acid. When the silage was treated with LAB and cellulase, the fermentation quality was improved. In the DS silage, aerobic bacteria and yeasts were the dominant microbes and all the silages were of poor quality. The yeast and mold counts in the DS silage were high, and they increased rapidly during aerobic exposure. As a result, the DS silages spoiled faster than the QS silages upon aerobic exposure. Conclusion: DS results in poor silage fermentation and aerobic deterioration. The microbial additive improved QS silage fermentation but was not effective for DS silage.

• Food Science and Industry
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• v.51 no.1
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• pp.72-80
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• 2018

Yogurt, which has long been consumed as a longevity food, is characterized by a large number of lactic acid bacteria. The sales of yogurt market have increased for the past three years due to research findings that the intestinal microbial environment is closely associated with many human diseases and the well-being trend of recent consumers. The recent trends in the yogurt market have focused to low sugar content, functionalities such as enhanced immunity, and yogurt for freezing. In addition, recent yogurt products tend to be labeled for certain lactic acid bacteria having functionality in their products. Many yogurts have names of specific lactic acid bacteria on their products, such as 'Activia' and 'Bifidus'. We monitored the 'Bifidus' products in the market for reflecting its regulated counting in their products required to contain more than 10 million Bifidobacteria according to the revised lactic acid bacteria-counting test of Food Code 2015.

• Journal of Life Science
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• v.22 no.10
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• pp.1324-1329
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• 2012

The objective of this study was to evaluate the in vitro effects of organic acids on methane emission and ruminal fermentation characteristics. We expected our methodology to result in a decrease of methanogens attached to the surface of rumen ciliate protozoa by addition of organic acids and in particular a decrease in methane emission. A fistulated Holstein cow of 650 kg body weight was used as a donor of rumen fluid. Organic acids (aspartic acid, fumaric acid, lactic acid, malic acid, and succinic acid) known to be propionate enhancers were added to an in vitro fermentation system and incubated with rumen fluid. The microbial population, including bacteria, protozoa, and fungi, were enumerated, and gas production, including methane and fermentation characteristics, were observed in vitro. Organic acids appeared to affect the rumen protozoan community. The rumen protozoal popuation decreased with the addition of aspartic acid, fumaric acid, lactic acid, and malic acid. In particular, the methane emission was reduced by addition of lactic acid. The concentration of propionate with all organic acids that were added appeared to be higher than that of the control at 12 h incubation. Addition of organic acids significantly affected rumen bacteria and microbial growth. The bacteria in added fumaric acid and malic acid was significantly higher (p<0.05) and protozoa was significantly lower (p<0.05) than that of the control. Microbial growth with the addition of organic acids was greater than the control after 48 h incubation.

• Microbiology and Biotechnology Letters
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• v.6 no.1
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• pp.17-22
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• 1978

The microbial and chemical changes, and characterization of the predominant acid-producing bacteria in the fermenting pig feces blended with corn meal at a ratio of 50：50 were studied. The fermentation was dominated by lactobacilli, which multiplied rapidly for the first 24 hours. The acid produced during the fermentation caused rapid pH drop to pH 4.5 and halted the growth of E. coli and yeast. The initial acid producing bacteria in the mixture was predominantly Streptococcus species, which were reduced in number rapidly. After 7 days of fermentation, three lactobacilli species were appeared L. acidophilus, L. fermenti, L. delbrueckii. Chemical changes during the fermentation were also studied. The lactic acid fermentation imparted a good tangy acid flavor to the corn-feces mixture by removing or covering the .fecal ordour and made the corn-feces mixture palatable for the animal as well as halted the unwanted microbial flora. We hope the lactic acid fermentation will replace the heat processing in the utilization of animal feces.

• Journal of Korean Medicine for Obesity Research
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• v.16 no.1
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• pp.11-18
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• 2016

Objectives: To confirm microbiological change and cytoprotective effect of Samjung-hwan (SJH) which fermented by Lactic acid bacteria from natural fermented SJH. Methods: SJH was fermented by Lactobacillus brevis and Lactococcus lactis subsp. lactis from natural fermented SJH. After 1 week of fermentation, we analysed pH and microbial profiling. We also performed measuring total polyphenol total flavonoid contents and 1,1-Diphenyl-2-picryhydrazyl (DPPH) free radical scavenging activity to investigate antioxidant ability. Cell viability was performed by using HepG2 cell. Results: pH of lactic acid bacteria inoculated group and non-inoculated group was decreased and total counts of lactic acid bateria for both group was increased after fermentation of SJH. Total polyphenol and flavonoid contents and DPPH free radical scavenging activity was increased in both group. Total polyphenol contents of lactic acid bacteria Inoculated group is more increased than non-inoculated group. HepG2 cell viability was increased in both group. Conclusions: SJH fermentd by Lactobacillus brevis and Lactococcus lactis subsp. lactis shows change in microbiological character and has cytoprotective effect. Further studies are required for investigating function of lactic acid bacteria during fermentation of SJH.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.429-437
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• 2020

This study aimed to investigate the change in physicochemical properties and lactic acid bacterial communities during kimchi fermentation at different temperatures (8, 15, and 25 ℃) using two molecular genetics approaches, multiplex polymerase chain reaction and 16S rRNA gene sequencing. The pH during fermentation at 8, 15, and 25 ℃ decreased from 6.17 on the initial fermentation day to 3.92, 3.79, and 3.48 after 54, 30, and 24 days of fermentation, respectively, while the acidity increased from 0.24% to 1.12, 1.35, and 1.54%, respectively. In particular, the levels of lactic acid increased from 3.74 g/L on the initial day (day 0) to 14.43, 20.60, and 27.69 g/L during the fermentation after 24, 18, and 12 days at 8, 15, and 25 ℃, respectively, after that the lactic acid concentrations decreased slowly. The predominance of lactic acid bacteria (LAB) in the fermented kimchi was dependent on fermentation stage and temperature: Lactobacillus sakei appeared during the initial stage and Leuconsotoc mesenteroides was observed during the optimum-ripening stage at 8, 15, and 25 ℃. Lac. sakei and Lactobacillus plantarum grew rapidly in kimchi produced at 8, 15, and 25 ℃. In addition, Weissella koreensis first appeared at days 12, 9, and 6 at 8, 15, and 25 ℃ of fermentation, respectively. This result suggests that LAB population dynamics are rather sensitive to environmental conditions, such as pH, acidity, salinity, temperature, and chemical factors including free sugar and organic acids.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.387-393
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• 2016

This study was conducted to determine the fermentative characteristics of wheat bran inoculated with a starter culture of direct-fed microbes as a microbial wheat bran (DMWB) feed additive. Wheat bran was prepared with 1% (w/w, 0.5% Lactobacillus plantarum and 0.5% of Saccharomyces cerevisiae) starter culture treatment (TW) or without starter culture as a control (CW). Those were fermented under anaerobic conditions at $30^{\circ}C$ incubation for 3 days. Samples were taken at 0, 1, 2, and 3 days to analyze chemical composition, microbial growth, pH, and organic acid content. Chemical composition was not significantly different between CW and TW (p > 0.05). In TW, the number of lactic acid bacteria and yeast increased during the 3 days of fermentation (p < 0.05) and the population of lactic acid bacteria was significantly higher than in CW (p < 0.05). After 3 days, the number of yeast in TW was $7.50{\pm}0.07log\;CFU/g$, however, no yeast was detected in CW (p < 0.05). The pH values of both wheat bran samples decreased during the 3 days of fermentation (p < 0.05), and TW showed significantly lower pH than CW after 3 days of fermentation (p < 0.05). Contents of lactic acid and acetic acid increased significantly at 3rd day of fermentation in TW. However, no organic acids were generated in CW during testing period. These results suggest that 3 days of fermentation at $37^{\circ}C$ incubation after the inoculation wheat bran with starter culture makes it possible to produce a direct-feed with a high population of lactic acid bacteria at more than $10^{11}CFU/g$.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.936-949
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• 2018

Changes in microbial community and physicochemical traits of chicken summer sausage made from spent layer thigh added with different level (0%, 0.1%, 0.3%, and 0.5% w/w) of ground chopi (Zanthoxylum piperitum) during manufacture were analyzed. The microbial community was profiled and analyzed by sequencing 16S rRNA gene using Illumina MiSeq. Samples were taken from raw sausage batter, after 15 h of fermentation, 8 h of cooking including cooling down, and 7 d of drying. The final pH of the sausage was reduced by the addition of ground chopi. However, no clear effect on water activity was observed. Ground chopi inhibited the development of red curing color after fermentation as it exhibited antimicrobial effect. However, the effect on species richness and microbial composition after cooking was unclear. Ground chopi delayed lipid oxidation during manufacture and the effect was dependent on the addition level. Fermentation reduced the species richness with a dominancy of lactic acid bacteria. The profile of microbiota in the raw batter was different from other stages, while the closest relationship was observed after cooking and drying. Proteobacteria was predominant, followed by Firmicutes and Bacteroidetes in raw samples. Firmicutes became dominating after fermentation and so forth, whereas other predominant phylum decreased. At genus level, unclassified Lactobacillales was the most abundant group found after fermentation and so forth. Therefore, the overall microbial composition aspects were mainly controlled during fermentation by the abundance of lactic acid bacteria, while bacterial counts and lipid oxidation were controlled by cooking and the addition of ground chopi.