• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1871-1880
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• 2016

Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

• Journal of Animal Science and Technology
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• v.63 no.6
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• pp.1411-1422
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• 2021

Lactobacillus acidophilus is a gram-positive, microaerophilic, and acidophilic bacterial species. L. acidophilus strains in the gastrointestinal tracts of humans and other animals have been profiled, but strains found in the canine gut have not been studied yet. Our study helps in understanding the genetic features of the L. acidophilus C5 strain found in the canine gut, determining its adaptive features evolved to survive in the canine gut environment, and in elucidating its probiotic functions. To examine the canine L. acidophilus C5 genome, we isolated the C5 strain from a Korean dog and sequenced it using PacBio SMRT sequencing technology. A comparative genomic approach was used to assess genetic relationships between C5 and six other strains and study the distinguishing features related to different hosts. We found that most genes in the C5 strain were related to carbohydrate transport and metabolism. The pan-genome of seven L. acidophilus strains contained 2,254 gene families, and the core genome contained 1,726 gene families. The phylogenetic tree of the core genes in the canine L. acidophilus C5 strain was very close to that of two strains (DSM20079 and NCFM) from humans. We identified 30 evolutionarily accelerated genes in the L. acidophilus C5 strain in the ratio of non-synonymous to synonymous substitutions (dN/dS) analysis. Five of these thirty genes were associated with carbohydrate transport and metabolism. This study provides insights into genetic features and adaptations of the L. acidophilus C5 strain to survive the canine intestinal environment. It also suggests that the evolution of the L. acidophilus genome is closely related to the host's evolutionary adaptation process.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.145-151
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• 2002

The effect of low pH on physiological changes was studied with the acidophilic green alga, Clamydomonas acidophila, UTCC 122. The growthrates (${\mu}$) were identical, $0.5{\sim}0.7\;day^{-1}$, at pH 3.7${\sim}$6.7 and no significantly different (ANOVA, p =0.134), showing cell volume reduced gradually as they were growing, whereas that at pH 2.7 was falling to zero and cell volume increased dramatically. Chlorophyll a concentration of the cultures incubated for one day was $191{\sim}255\;pg\;cell^{-1}$, after then it declined from $60{\sim}103\;pg\;cell^{-1}$ at pH 3.7${\sim}$6.7 except $210\;pg\;cell^{-1}$ at pH 2.7, which was directly related with cell volume. External carbonic anhydrase (CA) activity was varied from1.1 to$3.7{\times}10^{-4}\;E.U.\;mm^{-2}$, showing the gradualincrease during culture, except at 2.7 and pH 5.7. However there was not found any relationship among the pH gradient cultures. CA molecular mass of C. acidophila was 29 kBa, and concentration of that was identical in all cultures. The proteins of 41 kDa and 63 were not or very　faintly expressed in low pH cultures, in contrast that of 17 kDa more expressed. In this work, we found that C. acidophila could live optimally within a wide range of acidic pH, and 17 kDa of unidentified protein might be concerned with tolerating in low acid environment.

• Journal of Life Science
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• v.20 no.4
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• pp.487-495
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• 2010

A microorganism hydrolyzing carboxymethylcellulose (CMC) was isolated from seawater, identified as Psychrobacter aquimaris by analysis of 16S rDNA sequences, and named P. aquimari LBH-10. This strain produced an acidic carboxymethylcellulase (CMCase), which hydrolyzed carboxymethylcellulose (CMC), cellobiose, curdlan, filter paper, p-nitrophenyl-$\beta$-D-glucopyranoside (pNPG), pullulan, and xylan, but there was no detectable activity on avicel and cellulose. The optimal temperature for CMCase produced by P. aquimari LBH-10 was $50^{\circ}C$ and more than 90% of its original activity was maintained at broad temperatures ranging from 20 to $50^{\circ}C$ after 24 hr. The optimal pH of the CMCase was 3.5, and more than 70% of its original activity was maintained under acidic conditions between pH 2.5 and 7.0 at $50^{\circ}C$ after 24 hr. The optimal pH of CMCase produced by P. aquimaris LBH-10 seems to be lower than those produced by any other bacterial and fungal strain. $CoCl_2$, EDTA, and $PbCl_2$ at a concentration of 0.1 M enhanced CMCase-produced P. aquimaris LBH-10, whereas $HgCl_2$, KCl, $MnCl_2$, $NiCl_2$, and $SrCl_2$ inhibited it.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.1
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• pp.124-130
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• 2002

The present study was carried out to investigate the pretreatment of effects of water extract obtained from Eucommia ulmoides leaf (ELE) on hepatotoxicity of carbon tetrachloride ($CCl_4$) -treated rats. Thirty two healthy male Sprague-Dawley rats were divided into four groups, i.e. normal group (N), $CCl_4$-treated group (T), ELE-treated group (E), and ELE-treated group after injection of $CCl_4$(TE). The administration of $CCl_4$increased the activities of aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase in serum, but their activities were significantly decreased by the addition of ELE. Alkaline phosphatase activity in serum was significantly decreased in $CCl_4$-treated group, while the activity was not decreased by the extracts. Higher levels of HDL cholesterol was found in E and TE group which showed lower levels of total and LDL-cholesterol. Histopathologic findings by light microscopic examination showed fatty change, ballooning degeneration, acidophilic degeneration, spotty necrosis and zonal necrosis in $CCl_4$treated liver tissue. But the degree of liver damage was not identified in liver tissue of the TE group. These results indicated that Eucommia ulmoides leaf water extracts led migtigation of liver demage induced with $CCl_4$.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.4
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• pp.674-679
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• 2002

The toxicity and bioaccumulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) continues to be a focus of research in human and various species. The main human exposure is via the dietary route. This study was carried out to investigate the protective effect of Cornu Cervi Parvum extract on clinical parameters and hepatotoxicity in Sprague-Dawley rat (SD rat) accutely exposured to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Male SD rats received single intraperitoneal (ip) injection of TCDD (40 ㎍/kg), and administered 10 or 20 mg/kg/day of the ethanol extract oral injection for 4 weeks from 1 week before TCDD treatment. The gain in body weight was less in group treated with TCDD than in CON group, while that of C/H+ TCDD group (Cornu Cervi Parvum extract 20 mg/kg/day) increased. The decrease in spleen and testis weight caused by TCDD was prevented by Cornu Cervi Parvum extract 20 mg/kg/day. The fluctuation in BUN content, WBC and platelet count by TCDD intoxication were significantly attenuated by the ethanol extract treatment (20 mg/kg/day for 4 weeks). Treatments of rats with the extract (10 or 20 mg/kg/day) were significantly reduced AST and ALT levels compared with TCDD-treated group. Moderate swelling of hepatocytes, hyperchromatism, acidophilic cytoplasm and cytoplasmic vacuolation were observed in TCDD-treated animals (TCDD group). The administration of EtOH extract 10 or 20 mg/kg along with TCDD significantly alleviated the liver histopathological alteration induced by TCDD. These results suggest that Cornu Cervi Parvum extract can be useful as a protective agent against TCDD, an endocrine disruptor.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.209-220
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• 2015

The aim of this study was leaching valuable metal ions from mine waste rocks which were abandoned mine site using indigenous aerobic bacteria. In order to tolerate the the indigenous aerobic bacteria to the heavy metal ions they were repeatedly adapted in $CuSO_4{\cdot}5H_2O$ environment. As the repeated generation-adaptation progressed, the pH values of the growth-medium were gradually decreased. During bio-leaching experiments with indigenous aerobic bacteria raised in a heavy metal ion environment for 42 days, the pH of the leaching solution was decreased while increasing the adaptation period. The indigeous bacteria were much more active on the surface of Younhwa waste rocks which contained relatively few the chalcopyrite and Cu content than the Goseong mine waste rocks, and also the amount of Cu and Fe ions were leached more in the Younhwa sample(leaching rate of 92.79% and 55.88%, respectively) than the Goseong sample(leaching rate of 66.77% and 21.83%, respectively). Accordingly, it is confirmed that valuable metal ions can be leached from the mine waste rocks, if any indigenous bacteria which inhabits a mine environment site for a long time with heavy metal ions can be used, and these bacteria can be progressively adapted in the growth-solutions containing the target heavy metals.

• Applied Microscopy
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• v.33 no.1
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• pp.41-48
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• 2003

The hemopoiesis in human fetal spleen was studied with transmission electron microscope. There were undifferentiated proerythroblast, basophilic erythroblast, polychromatophilic erythroblast, and acidophilic erythroblast. Besides, enucleated nuclei and mitoses were present. Groups of erythroblastic cells were surrounded by certain cell. The structure was identical to erythropoietic island found in fetal liver. So, erythropoisis in spleen was developing in a pattern similar to fetal liver. Megakaryobalst were found in spleen, but there was no mature cells, cells in mitosis nor platelet formation. It was not clear whether megakaryoblast in circulation was trapped in spleen or participated in megakaryopoiesis. In summary, erythropoiesis took place in fetal spleen in a pattern similar to fetal liver and bone marrow. But it was not certain whether megakaryopoiesis took place in fetal spleen.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.97-104
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• 2007

Present study aims to investigate the effect of muddy water on gill and kidney tissues and blood components of Opsariichthys uncirostris amurensis in Imha reservoir. As a result of observing the gill tissues in muddy water with light and scanning electron microscopes, the edema, the exfoliation of epithelial cells and fusion of the secondary lamellae were observed. The space between gill lamellae was irregular, and a lots of muddy debris around the secondary lamellae were observed. In case of kidney tissues, the size of glomerulus was smaller and thickness of basal membrane was broader and the empty space in Bowman's capsule was wider than those of the control. The blood cells of O. uncirostris amurensis in muddy water were increased in number. Of the white blood cells, acidophilic granulocytes were highly distributed, and the shapes were irregular. Among the plasma components, the concentration of TP, ALB, A/G ratio, TG, CHOL, and AST were low, whereas that of the inorganic materials was high. Based on the above results, it is considered that muddy water possibly involves in the decrease of respiratory and excretory rates, giving rise to secondary lesion of tissues.

• Applied Microscopy
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• v.29 no.1
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• pp.43-56
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• 1999

The relationship between intravascular erythroblasts and Kupffer cells in the human fetal liver from 11 to 20 week gestation was studied ultrastructurally. The walls of the developing sinusoids consisted of two cell types devoid of basal lamina, the nonfenestrasted endothelial cells and Kupffer cells. Kupffer cells examined were easily identified by their content of phagosmes and their morphological features, and partially proliferated by mitotic division which was different way of proliferation from adult. Some extruded nuclei of acidophilic erythroblasts were trapped within Kupffer cells which exhibited various stages of intracellular digestion of the nuclei. During high activity of human fetal hepatic erythropoiesis, Kupffer cells were found in association with developing erythrob-lasts, which was similar with erythroblastic islands. The developing erythroblasts were partially surrounded by multilaminated membrane system of the Kupffer cell consisting erythroblastic island, or in contact with Kupffer cell via cytoptasmic processes in the sinu-soidal lumen. The presence of these islands was confirmed by transmission and scanning electron microscopic study. The results demonstrate that Kupffer cells in fetal heaptic erythropoiesis phagocytized expelled nuclei and contributed to erythropoiesis mechanically and physiologically by the hypertrophy and the formation of erythroblastic islands.