• 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.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.84-97
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• 2016

Isolates from Korean fermented soybean paste were identified as Enterococcus faecium SBP12, Pediococcus halophilus SBP20, Lactobacillus fermentum SBP33, Leuconostoc mesenteroides SBP37, Pediococcus pentosaceus SBP41, Lactobacillus brevis SBP49, Lactobacillus acidophilus SBP55, and Enterococcus faecalis SBP58 according to conventional morphological and biochemical characteristics, carbohydrate fermentation profiling, and 16S rRNA sequence comparison. Strain SBP20, SBP33, SBP49, and SBP55 showed very resistance to simulated gastric and intestinal juices with final populations exceeding 6 log CFU/ml, whereas cells of SBP12 and SBP58 after exposure to low pH were dramatically decreased within 2 h. Among 4 strains having good tolerance to gastrointestinal conditions, the high adhesive ability to HT-29 cells, antibiotic resistance, and antimicrobial activity against food-borne pathogens Bacillus cereus ATCC 11778 and Staphylococcus aureus ATCC 6538 were observed with SBP49 and SBP55, therefore, these two strains were confirmed as putative probiotic candidates. There was no significant difference between the sourdoughs fermented with SBP49 and SBP55 with respect to the values of pH, total titratable acidity, and viable cell count. During sourdough fermentation, SBP49 strain produced significantly greater amounts of lactic acid than SBP55 strain, which secreted large quantities of hydrogen peroxide. SBP49 and SBP55 strains producing the antimicrobial substances such as lactic acid, hydrogen peroxide, and bacteriocin effectively inhibited B. cereus and S. aureus inoculated in the sourdough.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.779-783
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• 2004

New food ingredient was developed to eradicate and protect against re-infection of Helicobacter pylori in fermentation broth of lactic acid bacteria (LAB) showing antimicrobial activity against pathogenic microorganisms such as H. pylori and Listeria monocytogenes. LAB strain CBT SL4 was identified as Pediococcus pentosaceus by 16S rDNA sequencing and its culture broth showed antimicrobial activity of 800 AU/mL against H. pylori in optimized fermentation process. Using thin layer concentration system and spray-typed fluid bed drier system, concentrated powder product showing activity of 12,800 AU/g was harvested. Product showed eradication and protection activities against H. pylori infection on feeding test (50 AU/day) using Mongolian gerbil infection model. After 4 weeks therapy of 8,000 AU/day, ${\Delta}13CO_2$ level (DOB30) decreased about 40% in urea breath test on patient with H. pylori infection. Result show concentrated culture product of P. pentosaceus CBT SL4 has eradicating and protecting activities against H. pylori infection and can be used as food-active ingredient for prevention of gastric and duodenum ulcer caused by H. pylori.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.11-17
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• 1996

Photosynthetic bacteria, strains KN 1-1, KN 2-1 and KN 2-3 were isolated from nature, and were studied for swine wastewater treatment. Growth of those photosynthetic bacteria were increased to 2~3 fold in organic-acid added medium(sodium acetate 1g, sodium propionate 1g and sodium butyrate 1g in Lascelles basal medium $1{\ell}$) than cultivation in Lascelles basal medium, and amount of bacteriochlorophyll a were increased to 1.5~2 fold. Chemical Oxygen Demand(COD) in swine wastewater using photosynthetic bacteria, strains KN 1-1, KN 2-1 and KN 2-3 were reduced 80%, 89% and 75%, respectively.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.391-398
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• 2010

This study was conducted to investigate the effects of feeding probiotics(gene modified yeast) on the egg quality in laying hens. The laboratory method of this study is as follow: In hens, 300, 36 weeks old ISA brown commercial layer, were employed in 13weeks feeding trial with a 7 days adjustment period. Dietary treatments are 1) control (basal diet) 2) Y0.3 (basal diet+0.3% probiotics), 3) Y0.5% (basal diet+0.5% probiotics), 4) PY0.3% (basal diet+0.3% plasmid modified probiotics), 5) PY0.5% (basal diet+0.5% plasmid modified probiotics). For overall period, hen-day egg production, egg weight (p<0.05) by dietary probiotic supplementation were recorded. Eggs were collected and weighed every day. Egg production number and egg production rate, egg weight, failure egg ratio and trouble egg ratio were recorded for 13weeks days. Diets PY0.3 and PY0.5 improved Egg production rate, egg production number and egg weight, compared to control diet (linear effect. p<0.05). And, diets PY0.3 and PY0.5 improved Egg production rate, egg production number, compared to Y0.3 and Y0.5 (linear effect. p<0.05). But, in Inferior egg and cracked egg, diets PY0.3 and PY0.5 did not tended to increase by dietary probiotic supplementation compared to control diet and Y group (0.3, 0.5) (linear effect. p<0.05). The productivity enhance on the egg quality in laying hens is considered from the effects of feeding probiotics(gene modified yeast).