• Preventive Nutrition and Food Science
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• v.9 no.2
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• pp.113-120
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• 2004

Selected microbiological and biochemical characteristics of the steeping process for the production of yukwa, a traditional Korean oil-puffed snack made of waxy rice, were investigated during steeping of waxy rice in water for 15 days. The lengthy steeping process was largely predominated by lactic acid bacteria (LAB), particularly, Lactobacillus and Leuconostoc. The predominat type of bacterium isolated was the Y26 strain tentatively identified as Lactobacillus plantarum. The titratable acidity of the steeping medium increased from 0.01 to 1.13%, in parallel with the decrease in pH ranging from 6.3 to 4.2 as the steeping period increased from 0 to 15 days. A high amount of lactic acid and to a much lesser extent, butyric acid, acetic acid, propionic acid, and succinic acid were detected during the steeping process. The amount of reducing sugars in the steeping medium increased from 0.61 to 10.43 mg/mL, whereas sucrose decreased from 0.46 mg% to an undetectable level. Starch degradation products including glucose, maltose and oligosaccharides ranging G3-G7 were not initially noticed, but their content increased during the steeping process until completion. However, no oligosaccharides larger than G8 were detected in the steeping medium. The activities of $\alpha$-amylase, $\beta$-amylase and protease in the steeping medium of waxy rice tended to rise increase with time during the steeping process. From these results, the lengthy steeping process in yukwa production can be characterized as the spontaneous fermentation, dominated by lactic acid bacteria, which is a necessary process for inducing biochemical modification of waxy rice.

• New & Renewable Energy
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• v.18 no.2
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• pp.9-17
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• 2022

In this study, we used the Flux Balance Analysis (FBA) program to examine the behavior of hydrogen and organic acids according to seasonal changes in food wastewater collected from D city. The results showed that average hydrogen conversion rates in spring, summer, autumn, and winter were 1.06, 0.71, 1.21, and 1.13 mol H₂/mol of hexose_added, respectively, indicating a significantly lower hydrogen conversion rate in summer than in other seasons. This phenomenon is believed to occur because the carbohydrate concentration of the incoming food wastewater is low. In addition, Lactobacillus, the lactic acid-producing bacterium, was 21.3% in spring, 27.2% in summer, 17.5% in autumn, and 22.6% in winter. The most distinctive feature of the microbial community in summer was that 15.3% of the Ilyobacter was analyzed. It was confirmed that Ilyobacter, which is involved in the production of acetic acid and propionic acid, is closely associated with the tendency of increasing acetic acid and propionic acid and thus contributes to organic acid change. Clostridium, a hydrogen-producing bacterium, was 76.2%, 50.8%, 78.3%, and 74%, in spring, summer, autumn, and winter, respectively. It was confirmed that Clostridium dominates the microbial community by approximately 70% or more in all seasons except summer.

• Microbiology and Biotechnology Letters
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• v.27 no.1
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• pp.15-22
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• 1999

Various lactic acid bacteria were isolated from Korean Kimchi in order to study their antimutagenic substances. Ames test using Salmonella typhimurium TA98 and TA100 showed the strain KLAB21 to have the highest antimutagenic activity among the 230 isolated strains against MNNG (N-methyl-N'-nitro-N-nitrosoguanidine), NPD (4-nitro-O-phenylenediamine), NQO (4-nitrosoquinoline-1-oxide) and AFB1 (aflatoxin B1). The strain was identified as Lactobacillus plantarum based on its morphological, cultural and physiological characteristics. Antimutagenic activity of L. plantarum KLAB21 was found in culture supernatant suggesting the bacterium secrete antimutagenic substance in the media. No mutagenic activity was found in the culture supernatant. The isolated strain L. plantarum KLAB21 showed much higher antimutagenic activity than L. plantarum IAM1261 which is being used industrially for fermented milk production. The antimutagenic activity of L.plantarum KLAB21 was reconfirmed by the spore-rec assay using spores of Bacillus subtilis H17($Rec^+$) and M45($Rec^-$).

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1321-1323
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• 2015

Lactic acid bacteria (LAB) are microorganisms that are believed to provide health benefits. Here, we isolated LAB from Indian fermented foods, such as traditional Yogurt and Dosa. LAB from Yogurt most significantly induced TNF-α and IL-1β production, whereas LAB from Dosa induced mild cytokine production. After 16S rRNA gene sequencing and phylogenetic analysis, a Yogurt-borne lactic acid bacterium was identified and classified as Lactobacillus delbrueckii subsp. bulgaricus, and it was renamed L. delbrueckii K552 for the further studies. Our data suggest that the newly isolated L. delbrueckii can be used for the treatment of immune deficiency disorders.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.308-315
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• 2011

The purpose of this work was to examine the antimicrobial activity derived from the lactic acid bacterium, UK-3 isolated from the vaginas of women of childbearing age. Various physiological and biochemical properties of this strain were characterized. Both the BIOLOG system and phylogenetic analysis using 16S rRNA sequencing were utilized for identification, and the strain was designated as Lactobacillus plantarum UK-3, and registered in GenBank as [JK266589]. Growth rate, production of organic acids (e.g., lactic acid and acetic acid), and pH during growth were monitored. The maximum concentrations of lactic acid and acetic acid were approximately 684.11 mM and 174.26 mM, respectively, and pH changed from 7.0 to 3.7 after 72 h of incubation. High performance liquid chromatography was used to confirm lactic acid and acetic acid production. Significant antimicrobial activity of the concentrated supernatant was demonstrated against various Gram-positive (e.g., Staphylococcus aureus, Staphylococcus epidermidis, Methicillin-resistant Staphylococcus aureus, Enterococcus faecalis, Neisseria species., Listeria monocytogenes), Gram-negative bacteria (e.g., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis), and yeast (e.g., Candida albicans) by the plate diffusion method. As a result, the concentrated L. plantarum UK-3 cultures had lower acidity and inhibited the growth of all microorganisms tested, whereas the growth of L. acidophilus was not affected.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1513-1517
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• 2006

One single lactic acid producing bacterium, isolated from kimchi, inhibited the growth and adherence of Helicobacter pylori to the human gastric epithelial cell line MKN-45. This isolate was identified as Lactobacillus plantarum and termed L. plantarum strain PL9011. The adherence of H pylori, in the presence of live or nonviable L. plantarum strain PL9011 (10-fold CFU), decreased to 14-20%. The spent culture supernatant of L. plantarum strain PL9011 resulted in the eradication of H pylori. This activity remained stable following neutralization and heat treatment, but not following pepsin treatment, thereby suggesting small peptides as the inhibitory factor. L. plantarum strain PL9011 did not produce any harmful metabolites or enzymes. The results obtained in this study suggest that the L. plantarum strain PL9011 may be a potential novel probiotic for the stomach.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.127-133
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• 2010

The purpose of this work was to investigate the antibacterial activity derived from a lactic acid bacterium, Lactococcus lactis HK-9, isolated from the feces of a 2-day newborn infant. We characterized the physiological and biochemical properties of this strain. Both the BIOLOG system and phylogenetic analysis using 16S rRNA sequencing were utilized for identification, and the strain was assigned to the Lactococcus lactis species, designated as L. lactis HK-9, and registered in GenBank as [GU936712]. We monitored growth rate, production of lactic acid and acetic acid as metabolites, and pH during growth. The maximum concentrations of lactic acid and acetic acid reached 495.6 mM and 104.3 mM, respectively, and the initial pH of the cultures decreased from 7.0 to 4.1 after incubating for 60 h. HPLC was used to confirm the production of lactic acid and acetic acid. Significant antibacterial activity of the concentrated supernatant was demonstrated against Gram-positive (e.g., Staphylococcus aureus, Enterococcus faecalis, Listeria monocytogenes, MRSA) and Gram-negative (e.g., Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Shigella sonnei) bacteria by the plate diffusion method. The antibacterial activity was sensitive to protease, and the molecular weight of the presumed bacteriocin molecule was estimated to be about 4 kDa by tricine-SDS-PAGE.

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.924-931
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• 2004

A bacteriocin-producing lactic acid bacterium, which strongly inhibited the Lactobacillus plantarum recognized as an important acid spoilage microorganism in kimchi fermentation, was isolated from kimchi. From morphological, physiological, sugar fermentation, biochemical tests, and l6S rDNA sequencing results, the isolate was identified as an Enterococcus sp. and designated as Enterococcus sp. K25. The bacteriocin produced by Enterococcus sp. K25 inhibited several Gram-positive bacteria, including Lb. plantarum, whereas it did not inhibit Gram-negative bacteria and yeasts. Optimal temperature and pH for the bacteriocin production were $25^\circ{C}$ and 5.5, respectively. Enterococcus sp. K25 was applied to kimchi manufacturing alone and together with other preservatives (i.e., chitosan and fumaric acid). In addition, growth of lactic acid bacteria, pH, and titratable acidity (TA) were measured during aging at $5^\circ{C}$ and $10^\circ{C}$. Inoculation of Enterococcus sp. K25 together with fumaric acid showed the most synergistic effect on extension of kimchi shelf-life. Compared to control (no addition), the treatment prolonged the kimchi shelf-life up to 6 days, whereupon the eight-point TA value recognized as the edible limit was reached.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.313-321
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• 2017

We aimed to develop commercialization process of encapsulation which is superior in productivity compared to existing methods by using sodium alginate. Also, in the same process, sodium alginate with chitosan was used to encapsulate lactic acid bacteria with the same process and then the viable cell counts of the two encapsulated lactic acid bacteria were compared. As a test result of the fluidized drying process developed by the present researchers, it was found that the drying time was shortened by 15 to 20 hours compared to the freeze drying method, but the number of viable lactic acid bacteria was about 75% as compared with freeze drying. However, considering the cost and time of drying, it can be confirmed that the commercialization process is possible by the fluidized bed drying method. When the number of viable cells of Ca-alginate capsule and Chitosan-alginate capsule were compared, it was confirmed that there were about $1{\times}10^9$ or more bacteria in the former and about $1{\times}10^3$ in the latter. The lactic acid bacterium capsules prepared by the present technique were stable for 96 hours or more at pH 4.65 and 6.01, but disappeared within 1 hour at pH 7.07 and 8.35. This suggests that the disintegration of lactic acid bacteria can be easily occurred in small and large intestine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.840-845
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• 1998

This study was conducted to produce the high quality of chunggugjang. The taste compounds of chunggugjang produced with Bacillus subtilis DC-2, pigment producing bacterium, were analysed, and palatability of chunggugjang was compared to that of commercial chunggugjang. Among the volatile organic acids, the contentof acetic acid was contained more than any other volatile organic acid. The major nonvolatile organic acid was lactic acid, followed by oxalic acid and citric acid. Tartaric acid was not detected. In case of free sugars, raffinose was sharply decreased between 72 and 96 hours after fermentation. Free amino acid was increased to 20 folds at 48 hours after fermentation compared to that of stemed soybean. As a result of sensory test, it was founded that the chunggujang fermented by Bacillus subtilis DC-2 was suitable to produce for commercial purpose.