• Korean Journal of Agricultural Science
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• v.42 no.3
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• pp.201-205
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• 2015

The experiment was conducted to evaluate the effects of pathogenic Escherichia coli on diarrhea, growth performance, and blood profile of weaned pigs. A total of 48 pigs were used and housed in individual pens of disease containment chambers for 16 d (4 d before and 12 d after the first challenge [d0]). The treatments were with or without the pathogenic E. coli challenge (F-18 E. coli strain; heat-labile, heat-stable, and Shiga-like toxins). Pigs were orally inoculated with a dose of $10^{10}cfu$ E. coli per 3 mL PBS daily for 3 days. The common nursery diet and water were available at all times. The ADG, ADFI, G:F, diarrhea score, ratio of fecal ${\beta}$-hemolytic coliforms from total coliforms (RHT), and blood profile were measured. The pathogenic E. coli reduced (P < 0.05) ADG from d0 to 6 (117 vs. 297 g/d) and from d0 to 12 (377 vs. 238 g/d) compared with the control. Meanwhile, the pathogenic E. coli increased (P < 0.05) diarrhea score (average 3.4 vs. 1.4) and RHT (average 82 vs. 11%) on d3, 6, and 9 and the number of white blood cells (17.59 vs. $13.48{\times}10^3/{\mu}L$) on d6 compared with the control. No differences were found on ADFI and others in the blood profile (total protein and hematocrit). In conclusion, pathogenic E. coli used in this experiment successfully caused mild diarrhea, increased number of white blood cells, and adversely affected growth rate of weaned pigs.

• Mycobiology
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• v.36 no.1
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• pp.13-18
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• 2008

Eight distinct bacteria were isolated form diseased mycelia of the edible mushroom, Pleurotus eryngii. 16S rDNA sequence analysis showed that the isolates belonged to a variety of bacterial genera including Bacillus (LBS5), Enterobacter (LBS1), Sphingomonas (LBS8 and LBS10), Staphylococcus (LBS3, LBS4 and LBS9) and Moraxella (LBS6). Among them, 4 bacterial isolates including LBS1, LBS4, LBS5, and LBS9 evidenced growth inhibitory activity on the mushroom mycelia. The inhibitory activity on the growth of the mushroom fruiting bodies was evaluated by the treatment of the bacterial culture broth or the heat-treated cell-free supernatant of the broth. The treatment of the culture broths or the cell-free supernatants of LBS4 or LBS9 completely inhibited the formation of the fruiting body, thereby suggesting that the inhibitory agent is a heat-stable compound. In the case of LBS5, only the bacterial cell-containing culture broth was capable of inhibiting the formation of the fruiting body, whereas the cell-free supernatant did not, which suggests that an inhibitory agent generated by LBS5 is a protein or a heat-labile chemical compound, potentially a fungal cell wall-degrading enzyme. The culture broth of LBS1 was not inhibitory. However, its cell-free supernatant was capable of inhibiting the formation of fruiting bodies. This indicates that LBS1 may produce an inhibitory heat-stable chemical compound which is readily degraded by its own secreted enzyme.

• Journal of Microbiology
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• v.44 no.3
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• pp.293-300
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• 2006

The Escherichia coli heat-labile enterotoxin B subunit (HLT-B) is one of the most powerful mucosal immunogens and known mucosal adjuvants. However, the induction of high levels of HLT-B expression in E. coli has proven a difficult proposition. Therefore, in this study, the HLT-B gene was cloned from pathogenic E. coli and expressed as a fusion protein with GST (glutathion S-transferase) in E. coli BL2l (DE3), in an attempt to harvest a large quantity of soluble HLT-B. The culture conditions, including the culture media used, temperature, pH and the presence of lactose as an inducer, were all optimized in order to obtain an increase in the expression of soluble GST-rHLT-B. The biological activity of the purified rHLT-B was assayed in a series of GMI-ELISA experiments. The findings of these trials indicated that the yield of soluble recombinant GST-rHLT-B could be increased by up to 3-fold, as compared with that seen prior to the optimization, and that lactose was a more efficient alternative inducer than IPTG. The production of rHLT-B, at 92 % purity, reached an optimal level of 96 mg/l in a 3.7 L fermentor. The specific GM1 binding ability of the purified rHLT-B was determined to be almost identical to that of standard CTB.

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.151-157
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• 1990

The maximum nitrogen fixation activity of the associative, microaerobic and acid tolerant bacteria, Azospirillum amazonense Kp1 was obtained with 0.2Kpa of $O_{2}$ and showed a reversible inhibition by the higher concentrations. Ammonium treatment caused a gradual inhibition of the activity up to 350mM. The nitrogenase systems were purified by gradient chromatography on DEAE-52 cellulose, heat treatment and preparative PAGE. The MoFe protein showed molecular weight of 210,000 including two nonidentical subunits with apparent molecular weights of 55,000 and 50,000 and an isoelectricpoint of 5.2 and contained 2, 24 and 28 atoms of Mo, Fe and acid labile S per molecule. The Fe protein revealed molecular weight of 66,000 including two types of subunits with molecular weights of 35,000 and 31,000 and an isoelectric point of 4.6, and contained 4 atoms of Fe and 6 atoms of S per molecule. The maximum specific nitrogenase activity attained 2,200 and 1,700nM $C_2H_4mg^{-1} min^{-1}$, respectively for MoFe and Fe proteins at pH7 and $35^{\circ}C$. The activity was lost after 10 and 30 days under the cold room ($4^{\circ}C$) condition for Fe and MoFe proteins, respectively.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.46-52
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• 2006

The mercury is among the most highly bioconcentrated toxic trace metals. Many national and international agencies and organisations have targeted mercury for the possible emission control. The mercury toxicity depends on its chemical form, among which alkylmercury compounds are the most toxic. A human cervix uterus cancer cell line HeLa cells was employed to investigate the effect of the toxic heavy metal mercury (Hg) and ionizing radiation. In the in vitro comet assays for the genotoxicity in the HeLa cells, the group of Hg treatment after irradiation showed higher DNA breakage than the other groups. The tail extent moment and olive tail moment of the control group were $4.88{\pm}1.00\;and\;3.50{\pm}0.52$ while the values of the only Hg treatment group were $26.90{\pm}2.67\;and\;13.16{\pm}1.82$, respectively. The tail extent moment and olive tail moment of the only 0.001, 0.005, 0.01 Hg group were $12.24{\pm}1.82,\;8.20{\pm}2.15,\;20.30{\pm}1.30,\;12.26{\pm}0.52,\;40.65{\pm}2.94\;and \;20.38{\pm}1.49$, respectively. In the case of Hg treatment after irradiation, the tail extent moment and olive tail moment of the 0.001, 0.005, 0.01 Hg group were $56.50{\pm}3.93,\;32.69{\pm}2.48,\;62.03{\pm}5.14,\;31.56{\pm}1.97,\;72.73{\pm}3.70\;and \;39.44{\pm}3.23$, respectively. The results showed that Hg induced DNA single-strand breaks or alkali labile sites as assessed by the Comet assay. It is in good agreement with the reported results. The mercury inhibits the repair of DNA. The bacterial formamidopyrimidine-DNA glycosylase (Epg protein) recognizes and removes some oxidative DNA base modifications. Enzyme inactivation by Hg (II) may therefore be due either to interactions with rysteine residues outside the metal binding domain or to very high-affinity binding of Hg (II) which readily removes Zn (II) from the zinc finger.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.402-408
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• 1994

Human plasma low density lipoprotein (LDL) is the major factor of coronary heart disease.But recent studies suggest the normal LDL can be realdily oxidized by oxygen free radicals and not interact with LDL receptors.Lipoprotei particles consist of lipid and protein, and fatty acids are prone to oxidatioin.The fatty acid compositions of LDL from Koreans was compared with that of Westerners.From the results, the raio of unsaturated fatty acids of korean and Westerner approximately 30 and 70%, respectively.which means Westerners are more labile in the lipid oxidation of LDL than Koreams.Normal LDL was incubated with $CuSO_4$ in PBS to lead for the peroxidation of LDL, and it was tested by the detection of TBARS and free radicals.Then, ascorbate, ${\alpha}-tocopherol$ and hyaluronic acid were found to have effects of antioxidants on LDL oxidation.The amount of free radical increased as the extent of oxidation increased.The time course of free radical formation was similar to TBARS.Therefore, determination of free radical by Luminometer was much more convenient than that of TBARS.

• Parasites, Hosts and Diseases
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• v.33 no.3
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• pp.195-200
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• 1995

The presence of biological response modifiers (BRMI-like effect was confirmed in peritoneal exudate (PE) of ToxopLnsmo gondii-infected ICR mice which inhibited Concanavalin A (Con A)-induced peritoneal Iymphocyte (PL) proliferation. During 5 days of PL incubation with $10{\;}\mu\textrm{g}/ml$ Con A with or without PE, 3H-thymidine uptake was measured for the last 24 hrs. Compared to uninduced control, PL proliferated by 7.3-fold with Con A induction_ When PE of infected mice was added, PL proliferation was inhibited by $74.0{\;}{\pm}{\;}11.9%$ whereas inhibition by PE of normal mice was $16.4{\;}{\pm}8.3%$. Inhibitory effect of PE increased exponentially from 3 days up to 4-5 days of survival after the infection. Inhibitory activity of PE was decreased concentration-dependently. Also the inhibition was diminished when the PE was treated with heat of $95^{\circ}C$ for 10 min orprecipitated with 10% trichloroacetic acid (TCA). In SDS-PAGE of PE, many minor bands appeared newly. Heat-labile protein molecule in PE exerted inhibitory activity to Con A- induced Iymphocyte proliferation.