• Food Science and Preservation
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• v.18 no.4
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• pp.612-619
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• 2011

Cronobacter sakazakii has been isolated from a wide range of environmental sources and from several foods of animal and plant origin. The objective of this study was to determine the resistance of C. sakazakii (ATCC 12868, ATCC 29004, and ATCC 29544) in cold, cold-freeze thaw, cold-acid, and cold starvation-freeze thaw stress. The number of C. sakazakii decreased to 1 log CFU/mL at $5^{\circ}C$ (cold storage) for 10 days. When C. sakazakii was cultivated at a low temperature ($13^{\circ}C$), the population of C sakazakii ATCC 12868 and 29004 increased to $10^9$ CFU/mL, and the population of C. sakazakii ATCC 29544 increased to $10^8$ CFU/mL. For C. sakazakii ATCC 12868 and 29004, the cold-adapted cells ($5^{\circ}C$ 24 hr) decreased by 4 log CFU/mL, and the low-temperature-cultivated cells ($13^{\circ}C$) decreased by 0.5 log CFU/mL. In this study, low-temperature cultivation enhanced the freeze-thaw cross-resistance due to the metabolic changes in the cells. Cold stress ($5^{\circ}C$ 48 hr, $13^{\circ}C$ cultivation) enhanced the cold-acid cross-resistance. The cold-starved cells in the sterilized 0.1% peptone water enhanced the freeze-thaw cross-resistance with significant differences (p<0.05). Therefore, the increased tolerance of the cold-adapted or low-temperature-cultivated C. sakazakii cells to freeze-thaw, acid, or starvation suggests that such environments should be considered when processing minimally processed foods or foods with extended shelf life.

• Research in Plant Disease
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• v.17 no.2
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• pp.129-135
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• 2011

Chitosan is a linear polysaccharide composed of randomly distributed ${\ss}$-(1-4)-linked D-glucosamine and Nacetyl-D-glucosamine. There have been many reports on the induced systemic resistance and in vivo antifungal activities of higher molecular weight chitosans with molecular weights over 3,000 amu (atomatic mass unit), but there are few papers on in vivo antifungal activities of low molecular weight chitosans (oligochitosans) with molecular weights less than 3,000 amu. In our study, an oligochitosan sample (320.3,000 amu) showed a potent 1-day protective activity with control values more than 94% at concentrations of 500 and 1,000 ${\mu}g$/ml especially against tomato late blight caused by Phytophthora infestans under growth chamber conditions. It also displayed a moderate 1-day protective activity with control values of 67.89% at concentrations of 500 and 1,000 ${\mu}g$/ml against wheat leaf rust and red pepper anthracnose. On the other hand, it showed a 16-hr curative activity against red pepper anthracnose, but not against tomato late blight and wheat leaf rust. In field experiments, oligochitosan effectively suppressed the development of late blight on potato and tomato plants with control values of 72% and 48%, respectively. The results strongly indicate that oligochitosan can be used as an eco-friendly organic material for the control of late blight on tomato and potato plants.

• Journal of Life Science
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• v.18 no.6
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• pp.845-851
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• 2008

${\beta}-Lactamase$, secreted from Bacillus sp. J105 strain was purified to a single band on SDS-PAGE by ammonium sulfate precipitation, ion exchange column chromatography and gel-filtration. The molecular weight of the purified enzyme was 31 kDa on SDS-PAGE and its isoelectric point was 7.35. Optimal pH and temperature for enzymatic reaction were 5 and $40^{\circ}C$, respectively. As a result of total amino acid composition analysis of the purified enzyme, Gly and Ala were occupied 14.1 and 13.3 mole %, respectively. Km and Vmax value of purified enzyme were 1.33 mM and 0.36 mM/ml using ampicillin as a substrate, respectively.

• Applied Biological Chemistry
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• v.12
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• pp.83-88
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• 1969

In order to inhibit sprouting of garlics during the storage period and the extend their storage life, garlics were irradiated by gamma-rays $(Co^{60})$ and kept at room temperature. The effects of gammaradiation on sprouting inhibition, chemical contents during storage, and spoilage molds were investigated and the results are as follows. 1. Garlics obtained from Muan showed the shorter dormancy period and sprouted earlier than those from Dangjin. 2. Regarding the radioresistance, some differences were found between garlics from Muan and Dangjin. 3. The sprout of garlics from both areas was completely inhibited at 10 Krad and remarkable effect on sprouting was observed even with 5 Krad in case of garlics from Dangjin. 4. The rates of loss in moisture and weight were lower in irradiated lots than control. 5. Change of sugar content was not observed with ${\gamma}-irradiation$ under 300 Krad. 6. Spores of Aspergillus niger and Aspergillus alliaceus were little germinated at a level of 300 Krad.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.249-253
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• 2016

The inky cap, Coprinellus congregatus, produces several laccase isozymes during its life cycle: both hyphal tip laccase and sclerotial laccase are involved in the fungal development. When this fungus was transferred to an acid liquid medium (pH 4.0-4.5), a new laccase was synthesized and secreted into the culture supernatant. In order to examine its regulation by external pH, green fluorescent protein gene was ligated at the downstream of the promoters having different lengths. These expression vectors having different promoter lengths were inserted into the fungal transformation vector, pBARGEM7-1. These expression vectors were introduced to the mating type a1 and a2 monokaryons, and the transformants were selected by the phosphinothricin resistance. Transformant a1 (a1TF) and transformant a2 (a2TF) were mated with each other to generate homozygotic dikaryon transformants. All these transformants were grown in neutral liquid medium for 5 days, and then the whole cell homogenates were transferred to the acidic liquid medium (pH 4.1). After 36 h incubation at $25^{\circ}C$, cells were harvested for the analysis of GFP expression. GFP expression was detected in the transformant having full-length promoter (2.0 kb), but other transformants having shorter length promoter (shorter than 1.29 kb) failed to show the fluorescence. Therefore, the acid-responsive element in the laccase promoter should be localized between -2.0 kb ~ -1.29 kb region.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.5
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• pp.684-691
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• 2010

The present study was conducted to evaluate the effect of resistant starch (RS) on the large bowel function and plasma lipids in rats with constipation induced by Loperamide. Animals were divided into six groups: normal control-5% cellulose, constipation-5% cellulose, constipation-5% pectin, constipation-5% RS-type 2 (RS2), constipation-8% RS2 and constipation-5% RS type 3 (RS3) groups, and fed experimental diets for five weeks. The results from RS groups were compared with those from other dietary fiber groups. The groups supplemented with RS3 or high level of RS2 showed significantly increased counts of bifidobacteria in the cecum than the other groups. The production of total short chain fatty acids in the cecal contents was significantly high in pectin, RS3 and high RS2 groups. The pH in the cecal contents of the RS supplemented groups was significantly decreased compared with the cellulose supplemented groups. The production of prostaglandin E2 in the colon mucus of the RS groups was higher than the normal group; however, it was significantly decreased compared to the cellulose or pectin supplemented constipated groups. The thickness of the mucus layer and the production of mucus from epithelial cells were significantly increased in RS3 group compared to the constipated cellulose group. Supplementation of resistant starch significantly elevated the ratio of HDL-cholesterol to total cholesterol and significantly lowered plasma atherogenic index compared with cellulose or pectin supplementation in constipated rats. The results of the present study demonstrated that resistant starch supplementation may help in improving the large bowel environment by stimulation of bifidobacterial proliferation, reduction of pH and inflammation factor and by increased production of mucus. It has also been found that an additional health benefit is improvement in lipid levels of serum.

• Korean Journal of Microbiology
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• v.32 no.1
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• pp.20-27
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• 1994

An inducible ${\beta}$-lactamase gene (bla) was identified and isolated from the chromosomal DNA of multiple drug resistant strains of Staphylococcus aureus. Determined base sequence of bla and of its flanking region was compared with those of bla genes identified on the staphylococcal plasmids pPC1, pI258, pI1071, and pUB101. Base sequence of 843 base-long structural gene of our bla was same as that of pPCl-, pI258-, and pS1-bla. However, HindIII recognition site Which is found in most of the bla genes at 140 base upstream from the structural gene was moved to the site of 370 base upstream from the structural gene. And one of the two direct repeat sequence found in downstream flanking region of pI1071-bla was deleted in our bla. Amino acid sequence homology analysis of the ORF located around HindIII recognition site reveals that this 80 amino acids-long polypeptide is C-terminus of transposase of Tn4001.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.501-507
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• 2010

Formaldehyde responsive protein(FRP) 1 belongs to the family of universal stress protein(USP) and is known to respond to stress caused by fumigation of gaseous volatile organic compounds(VOCs) such as formaldehyde and toluene. However, the molecular function of this protein is not well understood at cellular and molecular level. In this study, loss of function mutant of FRP1 generated by T-DNA insertion(frp1-4) has been isolated from Arabidopsis thaliana and the function of FRP1 was characterized. The loss-of-function mutant of FRP1 appeared slight growth defects with shorter stem and rosette leaves compared to wild type. In addition, the damage caused by exogenous VOCs was more severe in frp1-4 than in control. Therefore, Arabidopsis FRP1 seems to be the protein involved not only in the growth and development of plant but also the stress resistance against toxic volatile organic compounds.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.4
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• pp.216-224
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• 2023

Since maize (Zea mays L.) originated in central and south America, it requires warm climate conditions throughout its growing season. Growth halts when night-time temperatures drop below 10℃, and the plant may die if temperature reach -1.7℃. Thus, temperature should be maintained between 10 and 30℃ from seeding to maturity. The germination temperature for maize should be at least 8-11℃, whit an optimal range 32-34℃. Since temperature significantly affects the germination rate and period, it plays a crucial role in maize growth. In this study, we evaluated the quantity and feed value of 11 major varieties to determine those best suited for maize cultivation as feed in higher latitude, specifically in Democratic People's of Republic of Korea, below 38 degrees north. A cultivation test was also conducted in Suwon in Republic of Korea, to assess adaptability in areas south of Mt. Suyang. Among the varieties tested, Shinhwangok2 reached silking the fastest, in 65 days, while Gwangpyeongok took the longest at 75 days. The stem length of all varieties exceeded 230 cm. Gwangpyeongok had the tallest stems, while Daanok and Shinhwangok2ho displayed the highest ear ratios. Dacheongok presented the highest values in both dry matter and TDN quantity, with 31,420 kg/ha and 21,66 kg/ha respectively. Pyeonggangok had the highest crude protein content at 8.0%. TDN (%) ranged from 57-68%, with Hwangdaok reaching up to 68%. Based on these findings, Dacheongok and Pyeonggangok appear to be the most suitable varieties for cultivation in terms of both quantity and feed value.

• Polymer(Korea)
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• v.37 no.5
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• pp.587-591
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• 2013

Poly(3,4-ethylenedioxythiophene) (PEDOT) has good properties such as high conductivity, optical transmittance, and chemical stability, while offering relatively weak physicochemical properties. The main purpose of this paper is the improvement of physicochemical properties such as solvent resistance and pencil hardness of PEDOT. Carboxyl groups in the anionic type waterborne polyurethane (WPU) chains can effectively crosslink each other in the presence of aziridine, resulting in physicochemically robust PEDOT/WPU organic-organic hybrid conductive thin films. The electrical conductivity, optical properties, and physicochemical properties of the hybrid conductive film were compared by varying the solid content and WPU portion in the coating precursor solution. From the results, the transparency and surface resistance of the hybrid film show a decreasing tendency with increasing solid content in the coating precursor. Moreover, solvent resistance and hardness were dramatically enhanced by hybridization of PEDOT and crosslinked WPU due to curing reactions between carboxyl groups.