• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.4
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• pp.59-67
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• 1988

Anaerobic digestion at the temperature of $35-55^{\circ}C$ was conducted using an artificial sludge of uniform composition. The hydraulic retention time of 5 days was chosen because the temperature effect was effectively shown at a high loading. Inhibition of the methane fermentation decreased as the temperature increased. Acid fermentation was prevalent at the mesophilic and intermediate temperatures, while active methane fermentation took place at $55^{\circ}C$. Temperature not only affects activity of the microorganisms, but also affects physical and chemical properties of the sludge, Digestion inhibition was much reduced when the feed sludge was diluted, and active methane fermentation was possible at all temperatures. The digestion efficiency was governed by the organic loading rate as well as the hydraulic 10ading rate. No reduction of the digestion efficiency at $40-45^{\circ}C$, which had been referred to a critical temperature range, was observed. The digestion efficiency increased monotonically from mesophilic to thermophilic range. Improved settling properties of digested sludge was also recorded at higher temperatures.

• Journal of Life Science
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• v.25 no.12
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• pp.1450-1457
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• 2015

To overcome the depletion of fossil fuels and environmental problems in future, the research and production of biofuels have attracted attention largely. Thermophilic microorganisms produce effective and robust enzymes which can hydrolyze plant biomass and survive under harsh bioprocessing conditions. Caldicellulosiruptor bescii, which can degrade unpretreated plants and grow on them, is the one of the best candidates for consolidated bioprocessing (CBP). C. bescii can hydrolyze pectin efficiently as well as the major plant cell wall components, cellulose and hemicelluloses. Many glycosyl hydrolases and carbohydrate lyases with multidomain structure play an important role in plant biomass decomposition. Recently genetic tools for metabolic engineering of C. bescii have developed and bioethanol production from unpretreated biomass is achieved in C. bescii. Here, we review the recent studies for biomass degradation by C. bescii and bioethanol production in C. bescii in order to provide information about metabolic engineering of themophilic bacteria and biofuel development.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.77-83
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• 1999

The populations of microorganisms adhered on rice straws which had been ricked in the fields around Chungchong areas during the winter season from February to March in 1998 were investigated. The number of mesophilic bacteria including bacilli was generally high in the middle part of straw. And it appeared to be higher in the samples from rural areas than those from suburb. Thermophilic bacteria and actinomycetes were rarely to be detected in most samples. Coliform bacteria were detected in a few samples which collected from Kwanpyong-dong of Taejon-city, Jangpyong-meun and Jungsan-meun of Chongyang-koon, indicating that these areas were contaminated by sewage and livestock wastes. Following the fermentation of Chungkukgang employed the middle parts of straws from Mok-meun of Chongyang-koon as a source of microbial inoculum, qualities of the fermented products such as amino-nitrogen content, viscosity and protease activity, were examined: the application of rice straws resulted in better qualities of the fermented products when compared to the control, however the methods of application appeared to have little or no effect on the quality.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.57-65
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• 1999

Generation of gaseous ammonia has been a major problem in composting facilities. Microbial inocula. KMT-199(brand name: CompoBac$^{TM}$). was developed in INBI0NET CORPORATION and tested in the field for its ammonia reducing capability. When KMT-199 was applied. a ten-fold increase of mesophilic and thermophilic microorganisms was observed during the early stage of composting process. Also. the temperature and pH of early stage compost increased at a higher rate when compared to control. KMT-199 treated compost reached highest temperature of $75^{\circ}C$at day 9, indicating treatment could shift the maximum composting temperature to 3 days earlier The highest temperature also reached $3^{\circ}C$ higher than the control. The pH of compost gradually increased during composting. KMT-199 treated compost reached a plateau of pH 9.32 at day 15 after treatment, and then slowly decreased thereafter. On the other hand. pH of the control steadily increased until day 38 of composting. 29% reduction of gaseous ammonia generation during composting was observed compared to that of the control. KMT-199 amended compost resulted in a higher germination rate of radish seeds than the control. These results indicate that application of microbial inocula facilitates degradation of organic materials, including ammonia during the composting process.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.165-170
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• 2004

This study was conducted to investigate the effect of different surface soil management practices on soil microflora in volcanic ash soils of citrus orchard. Soil samples were collected from citrus orchards of clean cultivation, grass sod, and grass mulch system in May and September 1997. Soil chemical properties, populations of various microorganisms, enzyme activities, microbial biomass C were analyzed. Average soil pH were 4.7, and average nitrogen and organic matter contents were 6 and $140.2g\;kg^{-1}$, respectively. Aerobic bacteria were distributed at $26,2-47.3{\times}10^6cfu\;g^{-1}$ level. Among the aerobic bacteria Pseudomonas spp., Rhizobium spp., and thermophilic Bacillus spp. were dominant in most of the investigated orchard soils. Density of actinomycetes were low at $1.8-84.6{\times}10^5cfu\;g^{-1}$ level. Fungi were distributed at $26.4-182.1{\times}10^5cfu\;g^{-1}$ level and the density was higher in grass mulch and sward sites. In september, phosphomonoesterase activity was high at $239.6{\mu}g\;PNP\;g\;soil^{-1}\;h^{-1}$ in clean cultivated citrus orchards. Soil cellulase activity were higher at $602.6{\mu}g\;GE\;g\;soil^{-1}$\;24\;h^{-1}$ in grass sward cultivation than any other soil management practices. Soil microbial biomass C was higher in grass mulch cultivated orchards.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.675-681
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• 1994

[ $F_0$ ]-values of the canned tuna in cottonseed oil (CTCO) were investigated under different sterilizing conditions to optimize the energy consumption and microbiological safety. The $F_0$-values were measured using a microcomputer based technique. The exact cold point was not the volumetric center of the cans, and it was located in the center of meat mass in can which had ca. $6\%$ of head space. Location of the test cans in retort showed no remarkable influence on the $F_0$-values when the cans were jumble loaded. The process time before sterilization should be shortened as much as possible to prevent the contamination of microorganisms. Thermophilic spore forming bacteria found from raw and precooked tuna were Bacillus subtilis, Bacillus cereus and Bacillus pasteurii, and the most heat resistant was Bacillus subtilis. The rational $F_0$-value for the CTCO obtained from the preservation test was regarded as 6min.

• Journal of Mushroom
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• v.18 no.3
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• pp.274-279
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• 2020

This study was conducted to investigate the characteristics of the medium used on the composting step, comparing the excavator agitator with the self-propelled turner. The temperature of the outdoor composting medium tended to increase rapidly after flipping in the turner. The late composting medium temperature was maintained at the excavator treatment area (farm practice), and the late composting effect progressed. During the field composting stage, various microorganisms such as Bacillus spp., Actinomycetes, fluorescent Pseudomonas spp., and filamentous fungi were distributed in the medium, and the density of aerobic bacteria involved in the decomposition of the medium was increased. Under high-temperature composting conditions, blue fungi, and mesophilic actinomycetes were inhibited or killed. Thermophilic actinomycetes, which play an important role in decomposing organic matter, showed higher densities than those observed in farm practices in the self-propelled turner process. The length of rice straw was slightly shorter when the self-propelled turner was used, and the water content did not show any significant difference between treatments. The a and b values tended to increase as the inverter was turned over. The CN ratio of the composting broth was lowered from 23.1 to 16.2 for the 5th turnover in the context of farming practices, and from 23.3 to 16.9 in the context of the self-propelled turner. The yield of each treatment was increased by 20% in 1 period, 28% in 2 periods, and 26% in 3 periods; the overall yield was 23%.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.197-203
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• 1998

Although biological metabolism in soil is very important for evaluating the soil properties, most of researches have concerned mainly about physical and chemical sides. In this study, biological characteristics were examined to demonstrate the biota in the plastic film house soils. Contents of organic matter and phosphate in soil were increased with cultivation period. ECs of soil cultivated spinach and melon were $3.59dS\;m^{-1}$ and $3.46dS\;m^{-1}$ respectively: these values were higher than that of rose and flower, which were $1.23dS\;m^{-1}$ and $1.32dS\;m^{-1}$ respectively. The population of fluorescent Pseudomonas strains of the soil cultivated flowers: $113.8{\times}10^4{\sim}129.7{\times}10^4cfu\;g^{-1}$ was higher than that of leafy vegetables: $40.7{\times}10^4{\sim}97.9{\times}10^4cfu\;g^{-1}$ and fruiting vegetables: $25.0{\times}10^4{\sim}91.7{\times}10^4cfu\;g^{-1}$. However the number of Fusarium strains of the soil cultivated with flowers: $3.8{\times}10^2{\sim}4.0{\times}10^2cfu\;g^{-1}$ was lower than that of leafy vegetables: $4.3{\times}10^2{\sim}16.3{\times}10^2cfu\;g^{-1}$ and fruiting vegetables: $7.6{\times}10^2{\sim}30.0{\times}10^2cfu\;g^{-1}$. In relation to the cultivation period, the habitation density of aerobic bacteria, mesophilic Bacillus, thermophilic Bacillus, and fluorescent Pseudomonas strains was the highest in the soil cultivated over 11 years, but diversity index showed negative correlation with cultivation period. Microbial biomass C in these soils had positive correlation with each number of microorganisms including aerobic bacteria, actinomycetes, and strains of mesophilic Bacillus as well as the total number of these microorganisms.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.79-89
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• 1995

Changes of microbial activity and physicochemical environment during composting of papermill sludge(PMS) in the pilot plant equipped with an agitated bed reactor were monitored for establishing the efficient composting system. Microbial activity determined as the evolution of $CO_2$ increased for the first 10 days after introduction of PMS to the reactor and decreased thereafter. Population changes of microorganisms in the reactor-PMS were not typical as in windrow system. The ratio of thermophilic bacteria to mesophilic bacteria, however, increased slowly even 23 days after introduction. Temperature of PMS increased rapidly from the first day and reached $62^{\circ}C$ at 7 days after introduction and decreased slowly thereafter. The acidity of PMS was pH 6.8 initially, increased to pH 8.0 after 7 days and decreased to pH 7.4 after 23 days. Redox potential(Eh) of PMS was -320mV at the beginning of composting, but it was increased with time to reach -15mV after 23 days composting. However, Eh of PMS pre-sterilized before measurement was average 50mV, regardless of composting periods indicating the major role of microorganisms during composting process. Water content of PMS was 67% initially and decreased to about 50% after 23 days composting in the reactor. Less than 13 days-old compost inhibited growth of radish in the container mixture with bed soil. Based on statistical analysis of microbial and physicochemical parameters of PMS during composting, an equation was developed for determining compost maturity. A number of experiments using various organic wastes are required before application of the formular to the practical use.

• Journal of Food Hygiene and Safety
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• v.4 no.2
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• pp.119-132
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• 1989

Gamma irradiation as a new physical treatment was applied to comparative investigates with a conventional ethylene oxide fumigant on the microbiological and physicochemical qualities of selected spices and dry vegetables such as powdered red pepper, black pepper, welsh onion, onion, garlic, carrot, korean cabbage and instant ramyon soup. The microorganisms contaminated in the sample, including total viable count, thermophilic bacteria, aerobic spore and fungi counts between the $10^4\;to\;10^6/g$ range. Coliforms were found only in black pepper and welsh onion powder as the $10^2\;to\;10^3/g$ level. A radiation dose of 7 to 10 KGy were sterilized completely to the contaminated microorganisms, while ehthylene oxide (E.O.) fumigation reduced of them to the $10^3/g$ level. An optimum dose of irradiation was less detrimental than E.O. fumigation to the physicochemical properties of the sample. Sensory evaluation after three months of storage at room temperatures showed that the overall acceptability of irradiated sample was higher than that of the non treated control as well as E.O. fumigated samples. Comparison gamma irradiation with E.O. gas treatment showed that E.O. treatment was less effective than radiation in cotrolling microbial contamination of spices and vegetables.