• Molecules and Cells
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• v.21 no.3
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• pp.381-388
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• 2006

Heat shock proteins (Hsp) 70 are a ubiquitous family of molecular chaperones involved in many cellular processes. A yeast strain, ssa1/2, with two functionally redundant cytosolic Hsp70s (SSA1 and SSA2) deleted shows thermotolerance comparable to mildly heatshocked wild type yeast, as well as increased protein synthesis and ubiquitin-proteasome protein degradation. Since mRNA abundance does not always correlate well with protein expression levels it is essential to study proteins directly. We used a gel-based approach to identify stress-responsive proteins in the ssa1/2 mutant and identified 43 differentially expressed spots. These were trypsin-digested and analyzed by nano electrospray ionization liquid chromatography tandem mass spectrometry (nESI-LC-MS/MS). A total of 22 non-redundant proteins were identified, 11 of which were confirmed by N-terminal sequencing. Nine proteins, most of which were up-regulated (2-fold or more) in the ssa1/2 mutant, proved to be stress-inducible proteins such as molecular chaperones and anti-oxidant proteins, or proteins related to carbohydrate metabolism. Interestingly, a translational factor Hyp2p up-regulated in the mutant was also found to be highly phosphorylated. These results indicate that the cytosolic Hsp70s, Ssa1p and Ssa2p, regulate an abundance of proteins mainly involved in stress responses and protein synthesis.

• Journal of Life Science
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• v.9 no.1
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• pp.111-120
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• 1999

A bacteriocin-producing strain, J-105, was isolated from Kimchi and identified as Lactococcus sp. The optimum conditions for the bacteriocin production from the isolated microorganism were evaluated. For maximum yield of bacteriocin from Lactotoccus sp. J-105, the cell should be harvested at the early stationary phase and temperature, pH and NaCl concentration should be $25^{\circ}C$, pH 8.0 and without the addition of NaCl, respectively. Maltose should be used as a carbon source and organic nitrogen such as polypeptone should be used as a nitrogen source for the best yield. The bacteriocin from isolate was inhibitory against Acetobacter aceti, Bacillus subtilis and several strains of lactic acid bacteria. The bacteriocin of J-105 was sensitive to pepsin, but stable for heat treatment. It was stable even at autoclaving temperature for 15 min.

• Korean Journal of Poultry Science
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• v.12 no.2
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• pp.135-143
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• 1985

A total of eight strains of avian reoviruses were isolated from chickens with arthritis or stunted growth. The isolations were made from broilers or broiler breeders under 12 weeks of age. The viruses had a typical morphology of reoviruses with double capsid layers and 81nm of diameter. In agar gel precipitation tests, the isolates reacted with antisera prepared against S-1133 or R-1 strains of avian reoviruses and cross reacted with S-1133 antigen. They did not agglutinated RBC's from day-old chicks, adult chickens, guinea pigs, and horses. The isolates showed strong resistance against the treatments of chloroform, IUdR, and heat, When infectivities of the viruses were titrated in cell cultures of chicken embryo fibroblast, chicken embryo liver, and Vero cells, similar end points reached four to five days after inoculation, regardless of tell types and virus inoculation time, either inoculated simultaneously at the time of cell seeding or on confluency. Mean times of mortality of chicken embryos inoculated with the isolates via the chorioallantoic membrane ranged from 54 to 59 hours and that of S-1133 strain was 73 hours.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.647-656
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• 2002

High-strength steel in steel bridges is the key to achieving cost-efficiency because it facilitates lightweight construction and rationalizes structure. The future of high-strength steel is bright, with its use projected to expand. As such, it is necessary to evaluate precisely various factors affecting the process of fabricating high-strength steel, i.e., welding heat, strain hardening, and weldability and performance of the welded joints. This study therefore performed the maximum hardness test and y-groove weld crack test using welding processes such as SAW, FCAW, and GMAW, in order to investigate the welding performance and characteristics of welded Joints or high-strength steel produced in Korea such as SM570, POSTEN60, and POSTEN80. In addition, a series of welding tests was carried out to estimate the tensile strength, bending characteristics, absorbed energy, and hardness in welded joints.

• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.407-415
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• 1986

This study investigated whether a correlation exists between environmental physical and biochemical factors and adherence of Candida albicans to human buccal epithelial cells by using normal and UV-irradiated strains. The results were as follows: 1. The percentage of germ tube forming activities of normal Candida albicans was 91.5% and UV-irradiated Candida albicans was 15.0%. The $LD_{50}$ of normal strains in mice were $1.0{\times}10\;cells/ml$, but could not be observed in the UV-irradiated strains even with $1.0{\times}10\;cells/ml$. It demonstrated that the virulence is decreased in the UV-irradiated strain. 2. The adherence of normal Candida albicans to human buccal epithelial cells($166{\pm}29{\sim}207{\pm}17\;cells$/100 epithelial cells) was significantly greater than UV-irradiated Candida albicans($99{\pm}21{\sim}131{\pm}25\;cells$/100 epithelial cells). 3. Candida albicans cultured at $37^{\circ}C$ adhered to buccal epithelial cells($166{\pm}16{\sim}207{\pm}17\;cells$/100 epithelial cells) in greater numbers than cultured at $25^{\circ}C$($80{\pm}15{\sim}143{\pm}22\;cells$/100 epithelial cells). 4. On comparison of the adherence of viable and nonviable(heat-killed) Candida albicans to human buccal epithelial cells, the nonviable Candida albicans demonstrated poorer adherence than viable Candida albicans. 5. Adherence in vitro of Candida albicans to human epithelial cells appeared to be effected by the pH. The adherence ability was maximum increased at pH 7.0($187{\pm}22\;cells$/100 epithelial cells) other than experimental pH. 6. The adherence was proportional to the incubation time and the Candida cell concentration in the suspension. 7. A strong correlation was shown between germ tube forming activity and increased adherence of Candida albicans to human epithelial cells, indicating that germ tube forming activity were responsible for candidal virulence.

• Food Science of Animal Resources
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• v.22 no.1
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• pp.81-86
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• 2002

A bacteriocin producing lactic acid bacteria was isolated from ground beef and the strain was identified as Lactobacillus plantarum ssp. by use of API carbohydrate fermentation pattern and physiological tests. The bacteriocin produced by L. plantarum KU107 exhibited a good spectrum of activity against foodborne pathogens including Bacillus cereus, Escherichia coli, Listeria ivanovii, Listeria monocytogenes, Pseudomonas aeruginosa, Pseudomonas chlororaphis, Staphylococcus aureus, Staphylococcus intermedius, Salmonella typhimurium and Yersinia enterocolitica. The bacteriocin was active over a wide pH range and stable of heat treatment, and inactivated by treatment with proteases. A bacteriocin from L. plantarum KU107 was effetive in reducing S. aureus in tryptic soy broth. On the ground beef containing S. aureus was added with the crude bacteriocin, S. aureus was inhibited during storage period at 4$\^{C}$.

• Safety and Health at Work
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• v.9 no.2
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• pp.149-158
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• 2018

Background: Work comfort studies have been extensively conducted, especially in the underground and meteorological fields resulting in an avalanche of recommendations for their evaluation. Nevertheless, no known or universally accepted model for comprehensively assessing the thermal work condition of the underground mine environment is currently available. Current literature presents several methods and techniques, but none of these can expansively assess the underground mine environment since most methods consider only one or a few defined factors and neglect others. Some are specifically formulated for the built and meteorological climates, thus making them unsuitable to accurately assess the climatic conditions in underground development and production workings. Methods: This paper presents a series of sensitivity analyses to assess the impact of environmental parameters and metabolic rate on the thermal comfort for underground mining applications. An approach was developed in the form of a "comfort model" which applied comfort parameters to extensively assess the climatic conditions in the deep, hot, and humid underground mines. Results: Simulation analysis predicted comfort limits in the form of required sweat rate and maximum skin wettedness. Tolerable worker exposure times to minimize thermal strain due to dehydration are predicted. Conclusion: The analysis determined the optimal air velocity for thermal comfort to be 1.5 m/s. The results also identified humidity to contribute more to deviations from thermal comfort than other comfort parameters. It is expected that this new approach will significantly help in managing heat stress issues in underground mines and thus improve productivity, safety, and health.

• Korean Journal of Veterinary Service
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• v.30 no.3
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• pp.291-304
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• 2007

Mutants of an obligate aerobic bacterium, Vitreoscilla, that have deficiency in heat-labile catalase-peroxidase hydroperoxidase I (HPI) were created by EMS treatment. The catalase-peroxidase HPI-deficient mutant showed substantially lower peroxidase activity in exponential and mid-stationary phase compared with the wild type strain. In late stationary phase, the mutant exhibited no peroxidase activity. Peroxidase deficiency in the mutant was revealed by polyacrylamide gels stained for peroxidase activity. Characteristically, catalase levels in the mutant increased about 14- and 8-fold during growth in the exponential and stationary phases, respectively, compared to those in the wild type, suggesting a compensatory effect for protection from $H_2O_2$ toxicity. The mutant showed differences in physiology from the wild type: retardation in growth rate and decrease in oxygen consumption. Both the wild type and the catalase-peroxidase HPI-deficient mutant of Vitreoscilla had lower growth rates in media containing increasing $H_2O_2$ concentrations. However, the mutant exhibited an additionally decreased growth rate after 6 to 8 h of growth compared to the wild type. The wild type was resistent up to 20 mM $H_2O_2$, whereas the mutant was very sensitive to high concentrations of exogenous $H_2O_2$. Although elevated catalase levels would provide protection of the bacteria from the deleterious effect of $H_2O_2$, it did not appear to be complete. Cell-free extracts of the mutant showed decreased NADH oxidation rates and higher accumulation of $H_2O_2$ during this oxidation. These results may account for the impaired growth and earlier onset of death phase by the catalase-peroxidase HPI-deficient mutant of Vitreoscilla.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.18-18
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• 2010

Molecular insights on the role of plant growth promoting rhizobacteria (PGPR) in potato tuberization are reported in the present study. The PGPRwere isolated from the soil collected from potato fields of Highland Agricultural Research Centre, Pyeongchang, Korea and they were identified to the genus level based on the 16S rRNA sequence analysis. These PGPR were heat-killed, filtered and the filtrates were addedindividually at a concentration of $10^7\;cfu\;mL^{-1}$ in MS (Murashige and Skoog's) medium supplemented with 7% (w/v) sucrose to study their influence on in vitro potato tuberization. Tuber initiation occurred early in untreated control, while tuber growth was pronounced in case of PGPR treatments. The control explants showed tuber formation as a result of sub-apical swelling of stolons while several sessile tubers formed directly in the axils of nodal cuttings in case of PGPR treatments, which is an indication of strong induction for tuberization. Theexplants cultured on MS medium supplemented with bacterial isolate 6 (Bacillus firmus strain 40) showed highest average tuber yield (Ca. 12.56 g per treatment) after 30 days of culture, which was 3 folds increase over the untreated control. A significant increase in lipoxygenase (LOX1) mRNA expression and activity of LOX enzyme were also detected in the tubers induced on PGPR treatments as compared to untreated control. This LOX expression level correlated with increased tuber growth and tuber yield. Further studies focused on the role of bacteria cell wall components, growth regulators and signal molecules released by PGPR are under investigation to elicit clues for PGPR-mediated signal pathway controlling potato tuberization.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.31-39
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• 2012

The purpose of this study was to isolate bacteriocin-producing bacteria with antagonistic activities against pathogens from the intestines of pigs for probiotic use. Lactobacillus sp. AP 116 possessing antimicrobial property was selected from a total of 500 isolates. The AP 116 strain showed a relatively broad spectrum of inhibitory activity against Listeria monocytogenes, Clostridium perfringens, Pediococcus dextrinicus, and Enterococcus strains using the spot-on-lawn method. Bacteriocin activity remained unchanged after 15 min of heat treatment at $121^{\circ}C$ and exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. Maximum production of bacteriocin occurred at $34^{\circ}C$ when a pH of 6.0 was maintained throughout the culture during fermentation. According to a tricine SDS-PAGE analysis, the molecular weight of the bacteriocin was approximately 5 kDa. The isolate tolerated bile salts and low pH, and also induced nitric oxide (NO) in mouse peritoneal macrophages. Bacteriocin and bacteriocin-producing bacteria, such as Lactobacillus sp. AP 116, could be potential candidates for use as probiotics as an alternative to antibiotics in the pig industry.