• Korean Journal of Microbiology
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• v.30 no.3
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• pp.218-224
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• 1992

Recombinant plasmid shuttle vectors were constructed for genetic studies on the oxidation of carbon monoxide by carboxydobacteria. Two vectors. pYK322 (7.2 kb, Ap'. Tc') and pYK 324 (7.2 kb, Ap', Tc'), were constructed using pBR322 and pYK100. a small plasmid in Pseudomonas carbo,xydovorans. Four plasmids. pYK2IO (5.2 kb. Cm'), pYK220 (5.2 kb, Cmr), pYK230 (5.2 kb, Cm'), and pYK232 (5.2 kb. Cm'), were constructed using pACYC184 and pYK100. Transformation of several carboxydobacteria with pYK322 and pYK220 was round to be efficient when the cells were transformed by the methoti of Bagdasarian and Timmis (Curr. Top. Microbiol. Immunol. 96:47-67. 1982) with several modifications; cells growing on 0.2% succinate were harvested at the mid-exponential phase. 10 mM RbCl in transformation solution was substituted with 100 mM KCI. cclls in transformation solution were incubated for 12 h at 4'C before addition of DNA and heat shock was carried out for 3 min at 45$^{\circ}$C. Plasmid vectors used for transformation, however. were not detected from antibiotics-resistant transformants, suggesting that the vectors may be integrated into the chromosomal DNA.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.512-518
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• 1996

Eleven strains had been previously isolated from kimchi and identified in our laboratory. The ability of each strain in aroma production was investigated by sensory evaluation. Among them Saccharomyc s sp. YK-17, Saccharomyces sp. YK-18, Saccharomyces sp. YH-3 and Saccharomyces fermentati YK-19 produced fruity flavour. Especially, Saccharomyces fermentati YK-19 produced apple and pineapple-like flavours. Pichia media YK-11, Saccharomyces sp. YK-20 and Pichia chambardii YH-4 produced wine-like flavour. Debaryomyces sp. YK-6, Debarymyces coudertii YK-10, Saccharomyces sp. YK-12 and Pichia haplophilia YH-5 produced alcoholic flavours. Using the good flavour producing strains as starters, various groups of kimchi were fermented, and the sensory characteristics of each group such as odor, taste and total acceptability were evaluated. The acidic odor, moldy odor and taste were reduced by adding starter, while the fresh sourness odor and taste similar to fruity fiavour were increased by starter. Comparing with the control group, these odor, taste and total acceptability were increased in the starter-added groups, such as Pichia edia YK-11, Saccharomyces sp. YK-17, and Saccharomyces,fermentati YK- 19. Saccharomyces fermentati YK-19 added kimchi group was higher siginificantly (P<0.05) than the others at the total acceptability. Volatile compounds of the culture broth of Saccharomyces fermentati YK-19 were analysed by gas chromatography, and 6 species of esters and 4 species of alcohols were identified. Among them, the ester substances which broth largely responsible for the apple-like flavour in the sensory evaluation, were found to be ethyl 2-methyl butvrate, ethyl pentanoate and ethyl acetate.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.8-14
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• 2014

The objective of this work is to investigate and compare several functional properties of lactic acid bacteria (LAB), Lactobacillus casei SK-7 isolated from home-made yogurt and Lactobacillus bulgaricus YK-11 from commercial yogurt. Initially, physiological and biochemical properties of SK-7 and YK-11 were characterized. Phylogenetic analysis using 16S rRNA sequencing were performed to identify the strains, and the strain could be assigned to Lactobacillus casei and Lactobacillus bulgaricus, designated as L. casei SK-7 and L. bulgaricus YK-11. Phylogenetic tree of SK-7 and YK-11 was plotted based on 16S rRNA sequence comparisons. Production of lactic acid and organic acid, and pH changes in the cultures of SK-7 and YK-11 were monitored during 72 h. During the incubation period, several functional properties of L. casei SK-7 and L. bulgaricus YK-11 were examined. L. casei SK-7 and L. bulgaricus YK-11 cultures eliminated 93.9% and 88.2% of nitrite, respectively. Antioxidant activity of cultural supernatants of SK-7 and YK-11 were 62.6%, 54.9%, and activity of ${\beta}$-galactosidase were 14.9 units/mg and 13.1 units/mg, respectively. The antimicrobial activities were examined with 20-fold concentrated culture supernatants from the cultures of SK-7 and YK-11. The activities of SK-7 supernatants were clearly observed against all microorganisms in this work, whereas no activities were observed in YK-11 supernatants. Although it might be conducted additional functional research, functional properties of LAB isolated from home-made yogurt have been shown to be better than those of commercial yogurt in this work.

• Korean Journal of Microbiology
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• v.35 no.4
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• pp.270-276
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• 1999

Production of stress shock proteins in Burkholderia cepacia YK-2 in response to the phenoxyherbicide 2,4-dichlorophenoxyacetic acid(2,4-D) as an environmental contaminant was investrigated. The stress schock proteins were synthesized at different 2,4-D concentrations in exponentially growing cultures of B. capacia YK-2. This response involved the production of 43kDa and 41kDa GroEL proteins. The proteins were characterized by SDS-PAGE and Western blot using the anti-DnaK nad anti-GroEL monoclonal antibodies. Total stress shock proteins were analyzed by 2-D PAGE. Survival of B. cepacia YK-2 with time in the presence of different concentrations of 2,4-D was monitored, and viable counts paralleled the production of the stress shock proteins in this bacterium.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.6
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• pp.1071-1077
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• 2002

The purpose of this study was investigated the effects of YK-209 mulberry leaves on disaccharidase activites of small intestine and blood glucose-lowering in diabetic rats induced with streptozotocin (STZ). Male Sprague-Dawley rats weighing 100$\pm$10 g were randomly assigned to one normal and four STZ-induced diabetic groups; YK-209 0% mulberry leaves diet (DM group),0.1% YK-209 mulberry loaves diet (DM-0.1Y group),0.2% YK-209mulberry leaves diet (DM -0.2Y group), and 0.4% YK-209 mulberry leaves diet (DM -0.4Y group). Diabetes was induced by intravenous injection of 55 mg/kg body weight of STZ in sodium citrate buffer (pH 4.3) via tail vein after 3 weeks feeding of experimental diets. Rats were sacrificed at the 9th day of diabetic states. The functional ingredients in the mulberry leaves, the 1-deoxynojirimycin (DNJ) contents of YK-209 mulberry leaves was higher than those of the Cheongil mulberry leaves. ${\gamma}$ -Aminobutyric acid (GABA) and rutin contents of YK-209 mulberry leaves were 1.3 and 1.4 times higher than those of the Cheongil mulberry leaves, respectively, and vitamin C contents of YK-209 mulberry leaves were also higher than those of the Cheongil mulberry leaves. Intestine index was increased in all diabetic groups, compared with normal group but not significantly different among all diadetic groups. Level of blood glucose was decreased in diadetic rats by supplementation YK-209 mulberry leaves. The disaccharidase activities in proximal part of intestine such as maltase, sucrase, and lactase in YK-209 mulberry leaves supplementation groups were significantly lower than those of DM group, In conclusion, this research indicated that the functional ingredients of YK 209 mulberry leaves were higher than those of the Cheongil leaveses, and YK-209 mulberry leaves has the hypoglycemic effect in STZ-induced diabetic rats.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.2
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• pp.83-90
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• 1997

An unbleached hardwood kraft pulp was bleached in vitro with partially purified manganese peroxidase (MnP) from the fungus Phanerochaete sordida YK-624 without the addition of MnSO$_4$ in the presence of oxalate, malonate or gluconate known as manganese chelator, When the pulp was treated without the addition of MnSO$_4$, the pulp brightness increased by about 10 points in the presence of 2 mM oxalate, but the brightness did not significantly increase in the presence of 50 mM malonate. Residual MnP activity decreased faster during the bleaching with MnP without MnSO$_4$ in the presence of malonate than in the presence of oxalate. Oxalate reduced MnO$_2$ which already existed in the pulp or was produced from $Mn^{2+}$ by oxidation with MnP and thus supplied $Mn^{2+}$ to the MnP system. Thus, bleaching of hardwood kraft pulp with MnP, using manganese originally existing in the pulp, became possible in the presence of oxalate, a good manganese chelator and reducing reagent. Properties of partially purified MnPs from liquid cultures of white rot fungi, Ganoderma sp. YK-505, Phanerochaete sordida YK-624 and Phanerochaete chrysosporium were compared. MnP from Ganoderma sp. YK-505 was superior to MnPs from P. sordida YK-624 and P. chrysosporium in stabilities against high temperature and high concentration of $H_2O$$_2$. The MnP from Ganoderma sp. YK-505 differed in pH-activity profile from other MnPs. These data suggest that MnP from Ganoderma sp. YK-505 has different structure from those of other fungi. Bleaching of hardwood kraft pulp using the MnP from ganoderma sp. YK-505 is now in progress.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.826-833
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• 2002

This study was conducted to investigate the effects of YK-209 mulberry leaves on HMG-CoA reductase activity and lipid composition of liver in streptozotocin-induced diabetic rats. Sprague-Dawley male rats weighing 100 $\pm$ 10 B were randomly assigned as a normal group and four STZ-induced diabetic groups according to the level of dietary mulberry leaves supplement. The experimental diets were fed ad libidum, so that diabetes was experimentally induced by intravenous injection of STZ 55 mg/kg of body weight after feeding for 3 weeks. Animals were sacrificed on the 9th day of diabetic states. The levels of serum triglyceride, total-cholesterol and LDL-cholesterol in DM group were higher than mulberry leaves supplemented groups and normal group, but those of the mulberry leaves supplemented groups were significantly decreased to normal level. In contrast, the leavels of serum HDL-cholesterol in DM group was significantly reduced than that of normal group, but mulberry leaves supplemented groups were increased to normal level. Atherogenic index in DM group was higher about 3 fold than the normal group but the DM-0.1Y and DM-0.2Y groups were maintained the normal level. Contents of total lipid and triglyceride of liver in DM group were significantly lower than that of normal group, but the mulberry Leaves supplemented groups increased than that of DM group. The contents of hepatic cholesterol in DM group was 160% higher than that of normal group, but the mulberry leaves supplementation groups maintained the normal level. The activity of hepatic 3-hydroxy -3-methylglutaryl Coenzyme A (HMG-CoA) reductase in DM group was 43% lower than that of normal group, but had no significant difference between DM-0.1Y, DM-0.2Y and normal groups. In conclusion, YK-209 mulberry loaves has improving effect of the lipid metabolism in STZ-induced diabetic rats through hepatic HMG-CoA reductase activity, and the change of lipids contents in serum and liver.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.471-474
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• 2001

To optimize the culture conditions for fungal pathogen YK101, the effects of culture medium, temperature and agitation on mycelium production were investigated. The optimum temperature and agitation for the cultivation of YK101 were $28^{\circ}C$ and 150rpm, respectively. The optimized medium was composed of 1.0- 2.0% total sugar from sucrose, 1.0% yeast extract and 0.05% $MgSO_4$ ${\cdot}$ $7H_2O$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.6
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• pp.1065-1070
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• 2002

The purpose of this study was investigated the effects of YK-209 mulberry leaves on antioxidative defense system of liver in diabetic rats induced with streptozotocin (STZ). Male Sprague-Dawley rats weighing 100$\pm$10 g were randomly assigned to one normal and four STZ-induced diabetic groups; YK-209 mulberry leaves free diet (DM group),0.1% YK-209 mulberry leaves diet (DM-0.1Y group),0.2% YK-209 mulberry leaves diet (DM-0.2Y group) and 0.4% YK-209 mulberry leaves diet (DM-0.4Y group). Diabetes was induced by intravenous Injection of 55 mg/kg body weight of STZ in sodium citrate buffer (pH 4.3) via tail vein after 4 weeks feeding of experimental diets. Rats were sacrificed at the 9th day of diabetic states. Liver weight in all four diabetic groups were higher than normal group, but YK-209 mulberry supplementation groups were lower than DM group. Hepatic superoxide dismutase (SOD) activity was significantly decreased in all diabetic groups, compared with normal group. Hepatic glutathione peroxidase (GSHpx) activity was 7.3% decreased in DM group, compared with normal group, but those of DM-0.1Y and DM-0.2Y groups were maintained the normal level. The hepatic thiobarbituric acid reactive substances was markedly increased by 144% in DM group, compared with normal group, but those of DM-0. 1Y, DM-0.2Y groups were maintained the normal level. The contents of lipofuscin in liver were increased by 100% in DM group compared with normal group, but those of DM-0. 1Y, DM-0.2Y and DM-0.4Y groups were decreased to 42% 43% and 44%, respectively, compared with DM group. The hepatic superoxide radical (0$^2$-) contents in DM group were increased to 81%, compared with normal group, but those of DM-0.1Y and DM-0.4Y groups were similar to those of normal group. The present result indicate that YK-209 mulberry leaves regarded to suppress lipid peroxidation as an free radical scavenger system by the inhibition of oxidative stress.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.102-106
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• 2008

Formaldehyde, an indoor volatile organic compound, is considered toxic due to its carcinogenic risk. Recently, we isolated a formaldehyde-degrading bacterium Pseudomonas sp. YK-32. A crude enzyme prepared from YK-32 also degraded formaldehyde, suggesting that YK-32 cells have formaldehyde hydrogenase activity which is one of the important factors in formaldehyde degradation. The formaldehyde hydrogenase activity was increased 1.25 fold by adding 0.1 % glucose and formaldehyde to the culture medium. In addition, treatment with 1 mM EDTA as a permeabilizer promoted the degradation of formaldehyde and increased the enzymatic activity.