• Economic and Environmental Geology
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• v.43 no.6
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• pp.573-587
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• 2010

Bioleaching experiments were effectively carried out at $42^{\circ}C$, $52^{\circ}C$ and $62^{\circ}C$ to leach the more valuable metal ions from sphalerite using bacteria. The pH values of the bioleaching solution were constantly maintained for 10 days in the range of 2.40 to 2.55. In these bioleaching experiments, rod-shaped bacteria attached to the sphalerite surface were continuously observed in the sample. Along with the increase in the leaching temperatures, the concentration of Zn and Pb increased in the control sample of leachates, whereas the concentration of Fe increased in the sample containing bacteria. At $42^{\circ}C$, $52^{\circ}C$ and $62^{\circ}C$ the biological leaching content of Zn was found to be 9.5, 2.8 and 2.9 times higher than that in the chemical leaching content, respectively. At these temperatures, the content of Pb in the bacterial sample of the leachate was detected to be 14.8, 7.4 and 3.8 times higher than that of the control sample of the leachate, respectively.

• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.346-351
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• 1987

A cellulase gene of Clostridium themocellum was transferred to Escherichia coli by molecular cloning with pBR322. The gene was carried in a Hind III digested DNA sequence of about 1.8 kb. This Rind III fragment expressed activities on carboxymethyl cellulose (CMC) and on filter gaper in E. coli. The expression of clostridial cellulase gene in E. coli was studied and compared with the pro-ducts of cellulase genes in C. themocellum.

• Microbiology and Biotechnology Letters
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• v.23 no.5
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• pp.624-631
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• 1995

The fermentation characteristics of Saccharomyces cerevisiae F38-1, a newly isolated thermotolerant yeast strain from a high temperature environment have been studied using a fermentation medium containing 20% glucose, 0.2% yeast extract, 0.2% polypeptone, 0.3% (NH$_{4}$)$_{2}$SO$_{4}$, 0.1% KH$_{2}$PO$_{4}$, and 0.2% MgSO$_{4}$ without shaking at 30$\circ$C to 43$\circ$C for 5 days. The fermentability was over 90% at 30$\circ$C, 88% at 37$\circ$C, 77% at 40$\circ$C and 30% at 43$\circ$C. A similar fermentation result was obtained at pH between 4 and 6 at 30$\circ$C and 40$\circ$C. Aeration stimulated the growth of the strain at the beginning of the fermentation, but it reduced alcohol production at the end of alcohol fermentation. Optimal glucose concentration was determined to be between 18 and 22% at 40$\circ$C as well as 30$\circ$C, but the growth was inhibited at the glucose concentration of over 30%. A fermentability of over 90% was observed at 40$\circ$C in 2 days when the medium was supplemented by 2% yeast extract. A higher inoculum size increased the initial fermentation rate, but not the fermentation. A fermentability of over 90% was achieved in 2 days at 40$\circ$C in a fermentor experiment using an optimized medium containing 20% glucose and 1% yeast extract.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.517.1-517
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• 1986

고온 호알카리성 Bacillus K-17의 Protease gene의 구조해명과 성질을 알기 위해서, E. coli HB101에 pER 322를 Vector로 하여 Protease gene을 Cloning하여 형질전환 된 균주를 선정하였다. 선정균주의 pretense activity를 Bacillus K-17의 상대활성도와 매우 유사하였으며 균체외에 보다 많은 효소 활성도를 지니고 있었다. 제한효소 Hind III로 절단하면 약 1.8kb와 0.4kb의 2개의 fragments 가 생성되었으며 Southern hybridization 결과 Cloning 된 gene이 Bacillus K-17에서 유래된 것임이 확인되었다.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.313-318
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• 2006

A thermophilic bacterium producing the extracellular cellulase was isolated from soybean paste, and the isolate WL-12 has been identified as Bacillus licheniformis on the basis on its 16S rRNA sequence, morphology and biochemical properties. A gene encoding the cellulase of B. licheniformis WL-12 was cloned and its nucleotide sequence was determined. This cellulase gene, designated celA, consisted of 1,551 nucleotides, encoding a polypeptide of 517 amino acid residues. The gene product contained catalytic domain and cellulose binding domain. The deduced amino acid sequence was highly homologous to those of cellulases of B. licheniformis, B. subtilis and B. amytoliquefaciens belonging to the glycosyl hydrolase family 5. When the celA gene was highly expressed using a strong B. subtilis promoter, the extracellular cellulase was produced up to 7.0 units/ml in B. subtilis WB700.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.4
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• pp.86-95
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• 2002

Anaerobic digestion of municipal solid waste(MSW) is recently getting attention due to energy generation and abatement of global warming. MSW has high solid content and low nitrogen content. Its major component is cellulose and hemicellulose. The conversion rate of organic portion of MSW to methane is approximately 50%, representing $0.2m^3/kg$ VS. Long hydraulic retention time is required for high solid content and inoculum should be mixed with the feed. When MSW is digested anaerobically, maximum limit of C/N ratio is 25 and the optimum concentration of $NH_3-N$ is 700mg/L. lime and sodium bicarbonate are used to adjust pH. Excess addition of sodium bicarbonate above 3,500mg/L will cause sodium toxicity. Thermophilic anaerobic digestion is effective in the control of pathogen although its operation and maintenance is difficult. To optimize the anaerobic digestion of MSW, it is necessary to understand the mechanism of microorganims involved in anaerobic digestion.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.345-350
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• 1995

Another two different small composters with the double layer walls(Type 3 and Type 4) were made for dwelling house. One was insulated(Type 4) but the other uninsulated(Type 3). The change in microbial flora has been investigated through laboratory composting using these composters. The results were summarized as follows. 1. While the number of mesophilic bacteria decreased, that of thermophilic bacteria increased in winter. But thermophillic bacteria and mesophillic bacteria showed a tendency to increased in winter. But thermophilic bacteria and mesophillic bacteria showed a tendency to increase and decreas simultaneously in spring and summer at the early stage of composting. 2. The number of mesophilic actinomycetes ans thermophilic actinomycetes were decreased after I week in winter, while thermophilic actinomycetes rapidly increased in spring and mildly increased in summer. 3. The number of mesophilic fungi and thermophilic fungi had a tendency to increase and decrease simultaneously at an early stage of composting except after I week in winter. 4. Mesophilic bacteria, actinomycetes and fungi showed no difference in the number of microbes, but the number of fungi in spring was smaller than in other sensons. 5. At the late stage of composting process, the number of mesophilic fungi was decreased in winter and summer but increased in spring.

• Microbiology and Biotechnology Letters
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• v.34 no.4
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• pp.363-367
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• 2006

Food wastes were decomposed into the Mugri (Isung Engineering, Korea), a food waste reduction machine, with adding sawdust of cryptomeria. Degradation effects were better when the machine worked at over 45$^{\circ}C$ than those at the lower temperature. Thermophilic bacteria were isolated from cryptomeria sawdust and the food waste products degraded by the machine. The isolates from cryptomeria sawdust were classified into 3 genera (Acinetobacter baumannii, Enterobacter sp. and Erwinia cypripedii) and almost all the isolates from the degraded products were partially identified as Bacillus sp. by 16S rDNA sequence analysis. The isolated thermophilic bacteria showed degradative enzyme activities. In the case of addition of the 30 thermophilic bacteria into the machine, degradation rate of food wastes was almost twice as high with increasing process temperature up to 6$^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.31-38
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• 2008

Animal carcasses have always been and continue to be a major burden in animal production. The main aim of this study is to evaluate the feasibility of thermophilic anaerobic digestion for animal carcasses. A batch test using ground meat and organ as the model substrate showed that animal carcasses arehighly biodegradable at thermophilic anaerobic condition. The volatile solids (VS) destruction and $CH_4$ yieldranged from 52.7 to 58.5% and from 220 to 243 mL/g VS, respectively, at initial substrate VS in the range of 1.5~7.7%. However, high ammonia concentration inhibited continuous operation at substrate VS above 2.5%. As ammonia is formed during the degradation of proteineous organic materials, the major constituent of animal carcasses, the only way to reduce the ammonia concentration would be dilution. Co-digestion with other waste stream without high nitrogen content is recommended as an economically feasible approach for thermophilic digestion of animal carcass.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.243-252
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• 2002

To develop indicators for soil health evaluation, biological characteristics of native soils from the different parent materials were studied. Survival rate of fluorescent Pseudomonas in soils was the lowest as 0.1% while those of thermophilic Bacillus and alkaliphilic bacteria were over the 90% by the soil drying stress. There was positive relationship between soil microbial biomass and organic carbon exudated from the microbial biomass by the treatment. The average air-drying effect of soils was 39.7% with ranges of 9.7~95.0%. The propagules of mesophilic Bacillus and Gram negative bacteria were increased by the re-wetting of dried soils. Soil pH affected positively to the recovering rate of microbial number. Average recovering rate of microbes was 65.3%, and there was positive relationship between microbial biomass recovery and fluorescent Pseudomonas population.