• Environmental and Resource Economics Review
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• v.19 no.3
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• pp.597-632
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• 2010

There is general agreement that global warming is occurring and that the main contributor to this probably is the buildup of green house gasses, GHG, in the atmosphere. Two main contributors are the utilization of fossil fuels and the deforestation of many regions of the world. The burning of fossil fuels increases atmospheric carbon while the burning of fuel-wood reducing fossil fuel consumption along with its forest source maintain an atmospheric carbon level. The standing timber in the forests is a carbon sink, as are wood buildings and structures, and fossil fuel in the ground. This paper is designed to examine a number of current issues related to mitigating the global warming problem through forestry. For this purpose, we develop a modeling approach by integrating timber market, fossil fuel market and carbon cycling model. We use discrete time optimal control theory to identify optimal time paths, the laws of motion, and stationary stats solutions of endogenous variables in the model. On the basis of these results, we identify the optimal amounts of subsidies to be provided or taxes to be imposed by the regulatory agency to mitigate atmospheric carbon accumulation. We also present a numerical example to help illustrate the characteristics of variables in the model when the social cost for atmospheric carbon incrementally shifts upward. A surprising result is that the social cost function for atmospheric carbon has a very smaller impact on the optimal rotation period than previous literature suggested.

• Journal of Soil and Groundwater Environment
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• v.12 no.2
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• pp.20-26
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• 2007

The microbial community properties of groundwater samples contaminated with landfill leachates were examined using Ecoplate including 31 sole carbon sources. The samples were KSG1-12 (leachate), KSG1-16 (treated leachate), KSG1-07 (contaminated groundwater), KSG1-08 (contaminated groundwater), and KSG1-13 (uncontaminated groundwater). Among the carbon sources used as substrates, 2-hydroxy benzoic acid, D,L-$\alpha$-glycerol phosphate, and D-malic acid were not utilized in any sample, while D-xylose, D-galacturonic acid, L-aspargine, tween 80, and L-serine were utilized in all 5 samples. The rest of substrates showed very different patterns among the samples. Average well color development (AWCD) analysis demonstrated that the potential activity on 31 substrates was in the order of KSG1-16 > KSG1-12 > KSG1-07 > KSG-08 > KSG1-13, which generally agrees with the degree of pollution, except KSG1-16. Principal component analysis (PCA) on similarity between samples showed two groups (KSG1-12, -07 and -08 vs KSG1-16 and -13), coinciding with contaminated and uncontaminated groups. Shannon index showed that the microbial diversities were similar among the samples.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.30-35
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• 1992

Two strains J2W and J2Y which were isolated from soil can utilize polyvinyl alcohol(PVA) as a sole carbon source. PVA was utilized symbiotically by the mixed culture of these two strains which could not utilize PVA in each respective pure culture. Effect of degree of PVA polymerization on the its utilization was examed, and there was remarkable difference among three kind of PVA(PVA 500, 1500 and 2000). The reconstruction of there two strains was carried out with other symbionts Pseudomonas sp. PW and Pseudomonas sp. G5Y which were able to utilize PVA. PVA utilization occured in each remixed culture of J2Y strain with Pseudomonas sp. PW J2W strain with Pseudomonas sp. G5Y, respectively. Identification of bacteria was based on morphological and biological chatacteristics, J2W and J2Y strain were similar to a strain of Pseudomonas pseudimallei and Xanthomonas campestris, respectively.

• Mycobiology
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• v.51 no.1
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• pp.36-48
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• 2023

Xanthoria elegans is a lichen symbiosis, that inhabits extreme environments and can absorb UV-B. We reported the de novo sequencing and assembly of X. elegans genome. The whole genome was approximately 44.63 Mb, with a GC content of 40.69%. Genome assembly generated 207 scaffolds with an N50 length of 563,100 bp, N90 length of 122,672 bp. The genome comprised 9,581 genes, some encoded enzymes involved in the secondary metabolism such as terpene, polyketides. To further understand the UV-B absorbing and adaptability to extreme environments mechanisms of X. elegans, we searched the secondary metabolites genes and gene-cluster from the genome using genome-mining and bioinformatics analysis. The results revealed that 7 NR-PKSs, 12 HR-PKSs and 2 hybrid PKS-PKSs from X. elegans were isolated, they belong to Type I PKS (T1PKS) according to the domain architecture; phylogenetic analysis and BGCs comparison linked the putative products to two NR-PKSs and three HR-PKSs, the putative products of two NR-PKSs were emodin xanthrone (most likely parietin) and mycophelonic acid, the putative products of three HR-PKSs were soppilines, (+)-asperlin and macrolactone brefeldin A, respectively. 5 PKSs from X. elegans build a correlation between the SMs carbon skeleton and PKS genes based on the domain architecture, phylogenetic and BGC comparison. Although the function of 16 PKSs remains unclear, the findings emphasize that the genes from X. elegans represent an unexploited source of novel polyketide and utilization of lichen gene resources.

• Journal of Korea Foresty Energy
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• v.23 no.1
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• pp.45-68
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• 2004

The word of lignin is derived from the Latin word 'ligum' meaning wood. Lignin is complex polymer consisting of coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol unit and has an amorphous, three dimensional network structure which is hard to be hydrolyzed by acid. Lignin is found in the cell wall of plants lignified. The mode of polymerization of these alcohols in the cell wall lead to a heterogeneous branched and cross-linked polymer in which phenyl propane units are linked by carbon-carbon and carbon-oxygen bonds. This polymerization of precursors, p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol to lignin is formed by enzymic dehydrolyzation. The reaction is initiated by an electron transfer which results in the formation of resonance-stabilized phenoxy radical. The combination of these radicals produces a variety of dimers, trimers and oligomers and so on. Lignin research has been divided into basic and practical application field. The basic studies contains biosynthesis, chemical structure, distribution in the cell wall and reactivity by reductants, oxidants and organic solvents. The application research will be approached the reaction of lignin in various pulp making involving pulp bleaching and its effect on pulp qualities. Lignin also will be studied for the production of fine chemicals, polymer products and the conservation into an energy source like petroleum oil because the amount of lignin produced in pulp making process is more than 51,000,000 tons per year in the world. Both basic and application research must lay emphasis on the development for the utilization of lignin and the pulping process. But these researches can not be completed without understanding lignin structure containing functional groups. Therefore, this paper was focused on the review of lignin formulation which has been studied since 1948 in chronological order. This review was based on monomers, dimers, trimers and tetramers of phenyl propane unit structures which were isolated and identified by different methods from various wood.ious wood.

• Microbiology and Biotechnology Letters
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• v.51 no.3
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• pp.257-267
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• 2023

The potential polyhydroxyalkanoates (PHA)-producing bacteria, Bacillus megaterium PP-10, was successfully isolated and studied its feasibility for utilization of pineapple peel waste (PPW) as a cheap carbon substrate. The PPW was pretreated with 1% (v/v) H₂SO₄ under steam sterilization and about 26.4 g/l of total reducing sugar (TRS) in pineapple peel hydrolysate (PPH) was generated and main fermentable sugars were glucose and fructose. A maximum cell growth and PHA concentration of 3.63 ± 0.07 g/l and 1.98 ± 0.09 g/l (about 54.58 ± 2.39%DCW) were received in only 12 h when grown in PPH. Interestingly, PHA productivity and biomass yield (Y_x/s) in PPH was about 4 times and 1.5 times higher than in glucose. To achieve the highest DCW and PHA production, the optimal culture conditions e.g. carbon to nitrogen ratios of 40 mole/mole, incubation temperature at 35℃ and shaking speed of 200 rpm were performed and a maximum DCW up to 4.24 ± 0.04 g/l and PHA concentration of 2.68 ± 0.02 g/l (61% DCW) were obtained. The produced PHA was further examined its monomer composition and found to contain only 3-hydroxybutyrate (3HB). This finding corresponded with the presence of class IV PHA synthase gene. Finally, certain thermal properties of the produced PHA i.e. the melting temperature (T_m) and the glass transition temperature (T_g) were about 176℃ and -4℃, respectively whereas the M_w was about 1.07 KDa ; therefore, the newly isolated B. megaterium PP-10 is a promising bacterial candidate for the efficient conversion of low-cost PPH to PHA.

• Clean Technology
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• v.30 no.2
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• pp.71-93
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• 2024

Recently, the establishment of a hydrogen-based economy and the utilization of low-carbon energy sources, particularly for shipping and power generation, have been in high demand in order to achieve carbon neutrality by 2050. In particular, ammonia is gaining renewed attention because it is capable of serving as a key facilitator for high-efficiency green hydrogen storage and transportation and it is also capable of serving as a low-carbon energy source. Although ammonia can be synthesized through the Haber-Bosch process, the high energy consumption and carbon emissions associated with this process result in minimal carbon reduction. To address the critical drawbacks of the traditional Haber-Bosch process, various thermochemical synthesis methods have been developed recently, allowing for the synthesis of ammonia with lower carbon emissions and a higher energy efficiency. Research is also progressing in the development of high-performance catalyst materials that are capable of demonstrating sufficient ammonia synthesis performance under milder process conditions compared to conventional methods. Additionally, a variety of different processes such as chemical-looping ammonia synthesis, plasma synthesis, and mechanochemical synthesis are being applied diversely. This review aims to provide a detailed overview of the emerging ammonia synthesis technologies that have been developed to effectively store green hydrogen for future applications.

• Applied Biological Chemistry
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• v.16 no.1
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• pp.1-11
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• 1973

In order to obtain the basic informations on the production of single cell protein from ethanol, 145 yeast strains utilizing ethanol as a sole carbon source were isolated from 32 soil samples in Korea. A yeast strain showing the highest cell yield among the isolated strains was selected and identified. The optimum culture condition, utilization of other carbon sources and the cultural characteristics for the selected yeast, and the chemical analysis of the yeast cell composition, and utilization of ethanol by the selected yeast were investigated. All the culture was carried out in the shaking flasks. The results obtained were as follows: 1. The selected yeast strain was identified as Debaryomyces nicotianae-SNU 72. 2. The optimum composition of the medium for the selected yeast is : Ethanol 40 ml, Urea 0.5 g, Potassium phosphate (dibasic) 0.5 g, Ammoium phosphate (monobasic) 0.15 g, Magnesium sulfate 0.05 g, Calcium chloride 0.01g, Yeast extract 0.005 g, Tap water 1000 ml. 3. The optimum pH was 5.0-5.5, the optimum temperature $30-33^{\circ}C$ and the aerobic state was unimportant. 4. Utilization of methanol, n-propanol, iso-propanol, n-butanol, iso-butanol, tert-amyl alcohol and acetic acid by the selected yeast was very weak. So substitution of the subtrate was thought to be impossible. 5. Studies on the propagation of the yeast cells showed that the lag phase of the yeast cells lasted 16 hours, and the logarithmic growth phase extended 16 to 28 hours. The specific growth rate was about $0.19\;hr^{-1}$ and the doubling time was 3.6 hours during the logarithmic growth phase. 6. As the result of the chemical analysis of the dry yeast cells, the content rate of the crude protein was 55.19 %, the content of others was similar to the average content of the yeast component. 7. After 34 hours cultivation, under the optimum culture condition investigated, the dry cell yield against the amount of the added ethanol was 53.4 % (W/V%), the dry cell yield against the amount of the utilized ethanol was 73.6 % (W/V%), the evaporation rate of ethanol was about 19.1 %.

• Microbiology and Biotechnology Letters
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• v.14 no.6
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• pp.461-466
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• 1986

A highly cyclodextrin glucanotransferase producing strain of Bacillus sp. was isolated from soil, and basic studies on the characteristics of the strain and its enzyme, conditions for the enzyme production, and the enzyme utilization were carried out. The isolated strain was aerobic, motile, endospore-forming and rod-shaped bacterium. Optimum pH and temperature for the enzyme action were 6.0 and 45$^{\circ}C$, and the enzyme was stable within 5$0^{\circ}C$, and between pH 6.0 and 10.0. The highest yield of the enzyme was obtained using the medium containing 2% corn starch as a carbon source, and 5% corn steep liquor, 0.1% urea and 0.25% ammonium sulfate as nitrogen sources. The fermentation conditions for the enzyme production in a jar fermentor were cetermined to be 3$0^{\circ}C$, 200rpm, 0.6vvm and 60hr cultural period. Stevioside transglycosylation catalyzed by this enzyme was identified by high performance liquid chromatography.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.909-915
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• 2002

The biodegradation of BTEX components (benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene) individually and in mixtures was investigated using the o-xylene-degrading thermo-tolerant bacterium Ralsronia sp. strain PHS1 , which utilizes benzene, toluene, ethylbenzene, or o-xylene as its sole carbon source. The results showed that as a single substrate for growth, benzene was superior to both toluene and ethylbenzene. While growth inhibition was severe at higher o-xylene concentrations, no inhibition was observed (up to 100 mg $l^-1$) with ethylbenzene. In mixtures of BTEX compounds, the PHS1 culture was shown to degrade all six BTEX components and the degradation rates were in the order of benzene, toluene, o-xylene, ethylbenzene, and m- and p-xylene. m-Xylene and p-xylene were found to be co-metabolized by this microorganism in the presence of the growth-supporting BTEX compounds. In binary mixtures containing the growth substrates (benzene, toluene, ethylbenzene. and o-xylene), PHS1 degraded each BTEX compound faster when it was alone than when it was a component of a BTEX mixture, although the degree of inhibition varied according to the substrates in the mixtures. p-Xylene was shown to be the most potent inhibitor of BTEX biodegradation in binary mixtures. On the other hand, the degradation rates of the non-growth substrates (m-xylene and p-xylene) were significantly enhanced by the addition of growth substrates. The substrate utilization patterns between PHS1 and other microorganisms were also examined.