• Korean Journal of Clinical Laboratory Science
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• v.47 no.2
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• pp.59-64
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• 2015

Lactic acid-producing bacteria such as Lactobacillus spp. function to ferment carbohydrates and produce ATP. Such Lactobacillus spp. are used for the production of commercial yogurts. Lactobacillus spp. are beneficial to the intestinal tract, and Lactobacillus acidophilus-containing yogurts have received considerable attention because of their preventive effects against early-stage cancer of the large intestine. In this study, lactic acid-producing bacteria were cultured from three different groups: commercial solid yogurt (for eating), commercial liquid yogurt (for drinking), and Lactobacillus acidophilus-containing yogurt. We first determined the optimum culture conditions for Lactobacillus spp. and then analyzed turbidity and pH in order to compare the growth abilities and lactic acid-production capacities among the groups. Finally, high-performance liquid chromatography was used to measure the lactic acid content in the culture supernatants, and the antibacterial activities against Staphylococcus aureus and Escherichia coli were compared among the three groups. The optimum culture conditions for Lactobacillus spp. were MRS medium at $25^{\circ}C$, for 24 h. The highest turbidity was found in L. acidophilus-containing yogurt, followed by liquid yogurt and solid yogurt. Similarly, the highest lactic acid production ability was found in L. acidophilus-containing yogurt, followed by liquid yogurt and solid yogurt. Culture supernatants from the three groups did not show any antibacterial activity towards S. aureus; however, supernatants derived from L. acidophilus-containing yogurt resulted in a 1.8 mm inhibitory zone against E. coli in a paper disk diffusion test. These results revealed the high level of lactic acid-production capacity and antibacterial activity in L. acidophilus-containing yogurt.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.825-830
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• 2009

Pharmaceutical compounds enter the water environment through the diverse pathways. Because their concentration in the water environment was frequently detected in the level of ppt to ppb, the monitoring system should be optimized as much as possible for finding appropriate management policies and technical solutions. One Factor At a Time (OFAT) approach approximating the response with a single variable has been preferred for the optimization of LC-MS/MS operational conditions. However, it is common that variables in analytical instruments are interdependent. Therefore, the best condition could be found by using the statistical optimization method changing multiple variables at a time. In this research, response surface analysis (RSA) was applied to the LC-MS/MS analysis of emerging antibiotic compound, sulfamethoxazole, for the best sensitivity. In the screening test, fragmentation energy and collision voltage were selected as independent variables. They were changed simultaneously for the statistical optimization and a polynomial equation was fit to the data set. The correlation coefficient, $R^2$ valuerepresented 0.9947 and the error between the predicted and observed value showed only 3.41% at the random condition, fragmentation energy of 60 and collision voltage of 17 eV. Therefore, it was concluded that the model derived by RSA successfully predict the response. The optimal conditions identified by the model were fragmentation energy of 116.6 and collision voltage of 10.9 eV. This RSA can be extensively utilized for optimizing conditions of solid-phase extraction and liquid chromatography.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.40-44
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• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.

• Journal of Food Hygiene and Safety
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• v.35 no.3
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• pp.252-260
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• 2020

This study was conducted to improve the standard method for vitamin B₁₂ and biotin contained in foods for special dietary uses to ensure the specificity of the complex matrix properties of foods. For the food code, the test method was improved to determine vitamin B₁₂ and biotin by high-performance liquid chromatography (HPLC)-UV using column-switching after concentration using immunoaffinity column. The immunoaffinity columns contain a gel suspension of monoclonal antibody specific to the vitamin of interest so that it can be used to concentrate the vitamin B₁₂ and biotin and remove interferences from the food extracts. Moreover, validation of advanced new methods was carried out to support the suitability of the proposed analytical procedure (specificity, linearity, detection limits (LOD), quantitative limits (LOQ), accuracy, and precision). The improved analytical method is being used to monitor relevant food items on sale. The results of this study showed that the new analytical method is suitable and appropriate for managing food intended for special dietary uses.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.232-240
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• 2001

One hundred twenty five bacterial isolates were obtained from the brown blotch-diseased oyster mushrooms collected from markets. Among them, 45 were determined as pathogenic bacteria and white line forming organisms(WLFO) were 6 strains and white line reaction organisms (WLRO) were 6 strains. All of the white line forming isolates were identified as Pseudomonas tolaasii which is a known pathogen of brown blotch disease of oyster mushroom by GC-MIS(Gas chromatography-microbial identification system). Six of the white line reacting organisms were identified as P. chlomraphis, P. fluorescens biotype A and type C. The rest of them were P gingeri, P. agarici, P. fluorescens biotype B, P. chloroyaphis, non-pathogenic P. tolaasii, P. putida biotype A and B etc. For spectrum of activity of tolaasin, culture filtrates from pathogenic isolates were examined by browning of mushroom tissue and pitting of mushroom caps. The weak pathogenic bacteria didn't induce browning or pitting of mushroom tissue. On the other hand, strong pathogenic isolates showed browning and pitting reaction on mushroom. An extracellular toxin produced by P. tolaasii, was investigated. The hemolysis activity test of 6 strains identified as P. tolaasii were 0.8∼0.9 at 600 nm and 3 strains of WLRO were 0.9∼1.0 and Pseudomonas app. were 1.0∼1.2. Observation of fresh mushroom tissue using confocal laser scanning microscopy was carried out for images of optical sectioning and vertical sectioning. Also images of brown blotch diseased oyster mushroom tissue after contamination P. tolaasii was obtained by CLSM.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.472-477
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• 2004

Hypoglycemie effect of Moutan Radicis Cortex (MRC) extract contained in Yukmijihuang-hwan was determined by investigating insulin-sensitizing and ${\alpha}-glucoamylase-suppressing$ actions. MRC was extracted with 70% ethanol, fractionated by XAD-4 column chromatography with mixture solvent of methanol and water, and utilized for hypoglycemic effect assay. Significant insulin sensitizing activities of MRC extracts were observed in 3T3-L1 adipocytes, giving MRC extracts with 1 ng/mL insulin reach glucose uptake level increased by 50 ng/mL of insulin alone. MRC methanol extracts of 20, 40, 60, and 80% suppressed ${\alpha}-glucoamylase$ activity in vitro. Peak serum glucose levels and area under curve were lower in Sprague Dawley male rats treated with MRC ethanol extract than those treated with cellulose in oral glucose tolerance test using 2 g dextrin/kg body weight. These data suggest MRC extracts contain effective insulin -sensitizing and ${\alpha}-glucoamylase-suppressing$ compounds for hypoglycemic activity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.156-160
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• 2005

We studied the effect of SMP (solid matrix priming) treatment, seed pretreatment for germination enhancement, to tobacco seeds by measurement of germination rate and contents of fatty acid, energy source for tobacco germination. The results were as follows. In result of germination test, germinative ability was the highest in KF109 at nine day treatment and in KB108 at seven day treatment. The composition of fatty acid in tobacco seed confirmed by gas chromatography were palmitic acid, stearic acid, oleic acid+elaidic acid, linoleic acid+linole­laidic acid, and $\alpha-linolenic$ acid. Palmitic acid, stearic acid, oleic acid and elaidic acid, and linoleic acid and linole-laidic acid were highest in KF109 at eight or nine day treatment and in KB108 at six or seven day treatment. Especially, content of oleic acid + elaidic acid, and linoleic acid+linolelaidic acid were changed largely by treatment, so these might be used for index to examine treatment effect.

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.1-9
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• 1992

Catecholamines, serotonin and their metabolites were measured in the posterior hypothalamus of urethane-anesthetized normotensive Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) using brain microdialysis which is a recently developed experimental method to measure the release of neurotransmitters and their metabolites at the localized brain area in vivo. Microdialysis probe was implanted stereotaxically to the rat posterior hypothalamus and perfused by Ringer's solution. Monoamines and their metabolites were quantified by reverse phase high performance liquid chromatography with electrochemical detection. In vitro recovery test of microdialysis showed that there exist inverse relationship between the perfusion flow rate and the relative recovery of neurochemical compounds. The estimated extracellular concentration of dopamine was about 32 nM, of norepinephrine 50 nM, of epinephrine 50 nM, of serotonin 73 nM, of 3, 4-dihydroxyphenylacetic acid (DOPAC) 281 nM, of homovanillic acid (HVA) 181 nM, and of 5-hydroxyindoleacetic acid (5HIAA) 3767 nM in the hypothalamic perfusate of the normotensive rat. There was no difference in the basal level of monoamines between the SHR and the WKY. In contrast, the level of DOPAC, HVA and 5HIAA in SHR was higher than that in the WKY, This study demonstrated that the microdialysis technique should be an applicable tool for in vivo measurement of central neurochemical substances.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.321-329
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• 2014

This experiment was conducted to establish an analytical method for residues of amisulbrom, as recently developed an oomycete-specific fungicide showing inhibition of fungal respiration, in crops using HPLC-UVD/MS. Amisulbrom residue was extracted with acetonitrile from representative samples of five raw products which comprised apple, green pepper, kimchi cabbage, potato and hulled rice. The extract was diluted with 50 mL of saline water and directly partitioned into dichloromethane to remove polar co-extractives in the aqueous phase. For the hulled rice sample, n-hexane/acetonitrile partition was additionally employed to remove non-polar lipids. The extract was finally purified by optimized Florisil column chromatography. On an octadecylsilyl column in HPLC, amisulbrom was successfully separated from sample co-extractives and sensitively quantitated by ultraviolet absorption at 255 nm with no interference. Accuracy and precision of the proposed method was validated by the recovery test on every crop samples fortified with amisulbrom at 3 concentration levels per crop in each triplication. Mean recoveries ranged from 85.3% to 105.6% in five representative agricultural commodities. The coefficients of variation were all less than 10%, irrespective of sample types and fortification levels. Limit of quantitation (LOQ) of amisulbrom was 0.04 mg/kg as verified by the recovery experiment. A confirmatory method using LC/MS with selected-ion monitoring technique was also provided to clearly identify the suspected residue. The proposed method was sensitive, reproducible and easy-to-operate enough to routinely determine the residue of amisulbrom in agricultural commodities.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.680-685
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• 2015

Phytochemicals in Codonopsis lanceolata leaves were saponins, triterpenes, tannins, and flavonoids, not alkaloids. The levels of total polyphenols and flavonoids in Codonopsis lanceolata leaves were measured to evaluate the antioxidant activity. C. lanceolata leaves showed strong 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and potent reducing power. In addition, C. lanceolata leaf extracts inhibited production of nitric oxide (NO) in lipopolysaccharide (LPS)-activated RAW 264.7 cells. To examine active phytochemical for antioxidant activity, aglycone fraction of C. lanceolata leaves was analyzed by high performance liquid chromatography (HPLC). Luteolin was identified as a main component of aglycone fraction and showed potent antioxidant activity as determined by a DPPH radical scavenging assay and reducing power test. These results suggest that C. lanceolata leaves are a good source of antioxidants.