• Journal of agriculture & life science
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• v.46 no.1
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• pp.163-176
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• 2012

TTo increase productivity of a strong extracellular alkaline protease (BCAP), stable strains of Bacillus clausii I-52 carrying another copy of BCAP gene in the chromosome were developed. Integrative vector, pHPS9-fuBCAP carrying BCAP promoter, ribosome binding site, signal sequence and active protease gene was constructed and transferred into B. clausii I-52, and integration of the constructed plasmid into chromosome was identified by PCR. An investigation was carried out on BCAP production by B. clausii I-52 and transformant C5 showing the highest relative activity of alkaline protease using submerged fermentation. Maximum enzyme activity was produced when cells were grown under the submerged fermentation conditions at $37^{\circ}C$ for 48 h with an aeration rate of 1 vvm and agitation rate of 650 rpm in a optimized medium (soybean meal 2%, wheat flour 1%, sodium citrate 0.5%, $K_2HPO_4$ 0.4%, $Na_2HPO_4$ 0.1%, NaCl 0.4%, $MgSO_47H_2O$ 0.01%, $FeSO_47H_2O$ 0.05%, liquid maltose 2.5%, $Na_2CO_3$ 0.6%). A protease yield of approximately 134,670U/ml was achieved using an optimized media, which show an increase of approximately 1.6-fold compared to that of non-transformant (83,960 U/ml). When the stability of transformant C5 was examined, the integrated plasmid pHPS9-fuBCAP was detected in the transformant after cultivation for 8 days, suggesting that it maintained stably in the chromosomal DNA of transformant C5.

• Journal of Practical Agriculture & Fisheries Research
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• v.26 no.1
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• pp.16-21
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• 2024

Green manure crops have a variety of benefits, including improving soil fertility, removing soil salinity, enhancing soil aeration and moisture regulation, reducing the use of chemical fertilizers, reducing nitrous oxide emissions, reducing herbicide use through weed-suppressive effects, promoting agricultural ecosystem protection and carbon dioxide absorption capacity. To find ways to increase the germination rate of legumes and green manure crop seeds, which are imported in large quantities every year. It was carried out that two seed priming methods, osmotic priming and heat treatment, and compared their effects. Heat treatment was treated for 10 minutes at 40℃ or 60℃, followed by rinsing with water. Osmotic priming was applied for 30 seconds in a saline solution with a specific gravity of 1.13. Overall, there was no significant difference in the final germination rate, but it was found that osmotic priming and heat treatment affected the germination speed. However, applying heat treatment and osmotic priming simultaneously did not affect the germination characteristics. Therefore, it is suggested that heat treatment and osmotic priming can increase the germination speed of soybean and green manure crops.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.59-67
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• 2017

The aim of this experiment was to investigate the effect of air suction rate (SR) during the composting process of swine manure mixed with sawdust used as a bulking agent. In the 25 L composting reactors, the suction rate (SR) was at four different treatment levels (100%, 200%, 300%, 400%), and were fixed on the based on constant aeration rate into the composting mixtures. The temperature reached to thermophilic phase within 2 days and it was maintained up to the $5^{th}$ day of the composting process in all reactors and then gradually decreased to room temperature at the end of the composting process. The moisture content (MC, %) of the initial mixtures was 64.27%, and it was reduced to 38.4, 33.08, 14.59 and 11.93 in the different suction rate of 100%, 200%, 300%, 400%, respectively in the end process. During the composting, the level of pH was increased from 6.83 to 8.67 and it gradually decreased to 7.56 in 100% and 200%(SR). At the same time, the pH values were reduced only up to 8.19 at 300%, and 8.08 at 400%(SR), showing that suction strengths of 100% and 200% were the better option for composting than those of 300% and 400%. The total Kjeldahl nitrogen (TKN) of initial composts mixtures was 2.3% and were changed in 3.3, 3.1, 2.5, and 2.3% at the end of the composting period from the 100%-400% (SR) variations respectively. These results also indicated that 100% and 200% (SR) were more affected by the dry mass loss as $CO_2$ and water evaporation. The initial value of C/N ratio was 25.17 and were significantly reduced to 11.88, 11.97, 14.31, and 14.72 at the end of the experiment, respectively from the 100%-400% (SR) variations. These results suggest that the suction rate (SR) of 100% and 200% relative to constant air supply would be the optimal conditions to produce high-quality compost.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.11
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• pp.599-606
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• 2017

The effects of microbubble-oxygen physicochemical method for the removal of organic pollutants, nitrogen, and phosphorus contained in animal manure were investigated using a laboratory scale single reactor. The characteristics of used livestock manure were $36,894{\pm}5,024mg\;TCOD/L$, $22,031{\pm}2,018mg\;SCOD/L$, $4,150{\pm}35mg\;NH_4-N/L$, and $659{\pm}113mg\;PO_4-P/L$. It was confirmed that the amount of organic pollutants, nitrogen, and phosphorus removal was increased by the use of oxygen rather than air as the gas supplied with the microbubble, and by input of larger oxygen amount. When the oxygen was fed with 600 mL flow rate per minute, TCOD and phosphorus removal were 2.5 times and 5.6 times higher than those of air supplied. As the microbubble-oxygen reaction time was longer, the removal rate of nutrients increased gradually. The removal rates of ammonium and phosphorus reach to $41.03{\pm}0.20%$ and $65.49{\pm}1.39%$, respectively, after 24 hours. When the coagulation treatment method was applied to increase phosphorus removal rate from the effluent of microbubble-oxygen treatment, the phosphorus was removed up to 92.7%. However, the removal rate of organic pollutants (TCOD) was as small as $28.7{\pm}0.2%$ within the first 6 hours, and then the negligible removal of TCOD was recorded. This study suggests that microbubble-oxygen can be applied not only livestock manure but also aeration tank of various wastewater treatment plant, which can reduce the load on the associated unit process and produce stable high-quality effluent.

• Korean Journal of Microbiology
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• v.34 no.1_2
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• pp.20-25
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• 1998

To obtain higher yield of 2,3-dihydroxybiphenyl(2,3-DHBP) dioxygenase by recombinant E. coli CK1092 carrying pcbC gene of Pseudomonas sp. P20, the environmental and physiological factors were investigated and the cultural conditions using jar fermentor were studied. E. coli CKl092 was grown in LB medium supplemented with 2% sucrose, as a basal medium. The effect of various metal ions on the enzyme production was investigated. In particular, the enzyme production increased in the presence of $Fe^{3+}$ and $Fe^{2+}$, and showed the maxium at the concentration of $10^{-5}M$. The enzyme production was increased by 55% in the medium containing $Fe^{3+}$ ($10^{-5}M$) ion. The optimal temperature and initial pH for cell growth were $37^{\circ}C$ and 7.0, respectively. In the culture using a fermentor at $37^{\circ}C$, the optimal conditions for the enzyme production were obtained at the initial pH 7.0, 1 v/v/m of aeration rate, 200 rpm of agitation speed. It was found that enzyme activity was higher when cultivated without pH control than with pH control.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.316-325
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• 2009

Adequate conditions of water content and aeration of container media are major environmental factors in the production of pot plant. This experiment was carried out to find optimum physical property of media for the production of small potted Ardisia in capillary mat irrigation system. The plant materials used in this experiment were Ardisia pusilla and Ardisia japonica. Seven substrates were formulated by blending perlite or fresh rice hulls at 20%, 40%, 60% (v/v) with sphagnum peat. Total pore space (TPS) increased by blending sphagnum peat with fresh rice hulls, but decreased by blending sphagnum peat with perlite. As fresh rice hull (FRH) and perlite content increased, air filled pore space (AFP) of substrate increased but container capacity (CC) decreased. Substrate blended with fresh rice hull was higher AFP than blended with perlite and the rate of increase was higher for FRH-containing substrate. As AFP increased, the $CO_2$ concentration in the pot decreased and the $CO_2$ concentration of substrate blended with FRH was higher than blended with perlite. The fresh and dry weight of Ardisia pusilla and A. japonica was the highest in the substrate contained 60% FRH, but the ratio of shoot dry weight to root dry weight was the lowest. The optimum total pore space, air-filled pore space, water holding capacity of substrate for the growth of Ardisia pusilla and A. japonica in the capillary mat irrigation system were 82.8%, 25.6%, and 57.2% respectively.

• Journal of the Korean GEO-environmental Society
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• v.5 no.4
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• pp.13-24
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• 2004

This study was carried out to plan the prevention of the generation and discharge of Acid Rock Drainage (ARD). The Acid Base Accounting(ABA) test was performed for geological materials such as pit wall, waste rock and stream sediments near the Imgi abandoned pyrophyllite mine in Busan, Korea. In addition, hydraulic characteristics were tested with the disk tension infiltrometer around the waste rock dump. Maximum Potential Acidity(MPA) of geological materials near the Imgi mine was 246.942kg $H_2SO_4/t$, and maximum Acid Neutralising Capacity(ANC) was 8.7kg $H_2SO_4/t$. These results indicate the pit wall and waste rock, except most of stream sediments are acid generating geological materials. These have salt and free hydrogen ion which resulted from oxidation of sulfides. Hence they could be convert rain water to acid rock drainage. Although the waste rock dump of the Imgi mine have very low infiltration rate, slopes of the waste rock dump have many "V" type erosion gullies and multi-layers. These gullies and multi-layers have coarse clastic particle layers which have very large hydraulic conductivity. Through this coarse clastic particle layer a large part of rain flow into ground. And also this layer could function as aeration path which induced oxidation of sulfide minerals and generation of ARD continuously.

• Korean Journal of Food Science and Technology
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• v.17 no.1
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• pp.25-32
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• 1985

Low-temperature in-bin paddy drying has been examined to study the limitations of this drying method under Korean weather conditions, the initial moisture content of the paddy, the bulk depth and the airflow rate. The results are reported and discussed with regard to drying time, energy requirements and costs, uniformity in the moisture content of the dried kernels and, finally, the quality of the paddy. The tests carried out during the paddy-drying period in 1981 and 1982 have shown that under Korean weather conditions paddy can be dried to safe storage conditions by continuous aeration with ambient air. Depending upon the initial moisture content of the kernels(19.2%-25.5% w.b.), the bulk depth(1.1-3.5m) and the airflow $(3.0-6.9m^3\;air/m^3\;paddy/min)$ the paddy could be dried within 5 to 17 days. The energy requirements and energy costs are shown to be considerably lower than for conventional high-temperature drying. No significant changes in the quality in terms of milling yield, cracking ratio, acid value and germination were observed.

• The Korean Journal of Mycology
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• v.32 no.2
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• pp.95-100
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• 2004

The main objectives of the study were to investigate cultural characteristics of Phellinus linteus. The optimum culture media for mycelial growth of P. linteus were MYA (malt yeast agar) and SMS (soybean powder malt Sucrose). Similarly, optimum temperature and pH were $30^{\circ}C$ and 6.0, respectively. Malt extract (2%, v/v) and yeast extract (0.2%, v/v) were optimum carbon and nitrogen sources. Similarly, 0.1% $KH_2PO_4$ was optimum mineral salt. Highest mycelial growth was observed when C/N ratio was 10 : 1. Optimum inoculum amount for flask culture was $5{\sim}6$ mycelial discs (6 mm diameter) per 100 ml of liquid medium, Highest mycelial dry weight was obtained when cultured in 100 ml liquid medium in 300 ml shaking flask after 20 days of shaking culture, For mass liquid culture (8 l), flask culture was homogenized and used as an inoculum. Optimum culture period and aeration rate for 8l fermentation culture were 12 days and 2.0 vvm, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.922-929
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• 2007

The complete oxidation of ammonia to nitrate is a distinctive two-step process divided into the oxidation of ammonia to nitrite(nitritation) by Nitrosomonas and the oxidation of nitrite to nitrate(nitratation) by Nitrobacter. The nitrogen removal via nitrite accumulation offers several advantages such as saving costs for aeration, saving carbon source and finally reduction of sludge discharge. In this work a suspended bioreactor coupled with membrane filtration(MBR) was used to find the process conditions of nitrite build-up. The MBR enables to reach sufficient nitrifying bacteria in the bioreactor, although the autotrophic bacteria can be easily washed out due to their lower growth rate. The dissolved oxygen concentration $c'_{O2}$ and ammonia concentration $c_{NH3}$ in the reactor were varied and investigated as parameters for nitrite accumulation. As a result the higher ammonia concentration in the reactor is very effective for starting nitrite build-up and the effect was strengthened in combination with lower dissolved oxygen concentration. With lower $c'_{O2}<0.3$ $mgL^{-1}$ $O_2$ and high $c_{NH3}=6.3\sim14.9$ $mgL^{-1}$ $NH_3N$ the 74% of the nitrite accumulation was achieved. Specially, it was found that the nitrite accumulation could occur not only in biofilm reactor as many references showed but also in the membrane bioreactor carried out in this study.