• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.723-731
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• 2015

Microalgae hold promise as producers of sustainable biomass for the production of biofuels and other biomaterials. However, the selection of strains with efficient and robust production of desirable resources remains challenging. In this study, we isolated a green microalga from Korea and analyzed its morphological, molecular, and biochemical characteristics. Microscopic and phylogenetic analyses demonstrated that the isolate could be classified into the genus Chlamydomonas, and we designated the isolate Chlamydomonas sp. KIOST -1. Compositions of protein, lipid, and carbohydrate in the microalgal cells were estimated to be 58.8 ± 0.2%, 22.7 ± 1.2%, and 18.5 ± 1.0%, respectively. Similar to other microalgae belonging to Chlorophyceae, the dominant amino acid and monosaccharide in Chlamydomonas sp. KIOST-1 were glutamic acid and glucose. On the other hand, the proportions of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids clearly differed from other species in the genus Chlamydomonas, and monounsaturated fatty acids accounted for a large portion (41.3%) of the total fatty acids in the isolate. Based on these results, Chlamydomonas sp. KIOST-1 has advantageous characteristics for biomass production.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1235-1243
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• 2020

The use of microalgal biomass as feedstock for biofuels has been discussed for decades as it provides a sustainable approach to producing fuels for the future. Nonetheless, its feasibility has not been established yet and various aspects of biomass applications such as CO₂ biofixation should also be explored. Therefore, in this study, the CO₂ biofixation and lipid/carbohydrate production potential of Chlorella sp. ABC-001 were examined under various nitrogen concentrations. The highest biomass productivity and CO₂ biofixation rate of 0.422 g/l/d and 0.683 g/l/d, respectively, were achieved under a nitrogen-rich condition (15 mM nitrate). Carbohydrate content was generally proportional to initial nitrate concentration and showed the highest value of 41.5% with 15 mM. However, lipid content showed an inverse relationship with nitrogen supplementation and showed the highest value of 47.4% with 2.5 mM. In consideration as feedstock for biofuels (bioethanol, biodiesel, and biogas), the sum of carbohydrate and lipid contents were examined and the highest value of 79.6% was achieved under low nitrogen condition (2.5 mM). For lipid-based biofuel production, low nitrogen supplementation should be pursued. However, considering the lower feasibility of biodiesel, pursuing CO₂ biofixation and the production of carbohydrate-based fuels under nitrogen-rich condition might be more rational. Thus, nitrogen status as a cultivation strategy must be optimized according to the objective, and this was confirmed with the promising alga Chlorella sp. ABC-001.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1403-1412
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• 2013

Ethanol fuel production from lignocellulosic biomass is emerging as one of the most important technologies for sustainable development. To use this biomass, it is necessary to circumvent the physical and chemical barriers presented by the cohesive combination of the main biomass components, which hinders the hydrolysis of cellulose and hemicellulose into fermentable sugars. This study evaluated the hydrolytic capacity of enzymes produced by yeasts, isolated from the soils of the Brazilian Cerrado biome (savannah) and the Amazon region, on sugarcane bagasse pre-treated with $H_2SO_4$. Among the 103 and 214 yeast isolates from the Minas Gerais Cerrado and the Amazon regions, 18 (17.47%) and 11 (5.14%) isolates, respectively, were cellulase-producing. Cryptococcus laurentii was prevalent and produced significant ${\beta}$-glucosidase levels, which were higher than the endo- and exoglucanase activities. In natura sugarcane bagasse was pre-treated with 2% $H_2SO_4$ for 30 min at $150^{\circ}C$. Subsequently, the obtained fibrous residue was subjected to hydrolysis using the Cryptococcus laurentii yeast enzyme extract for 72 h. This enzyme extract promoted the conversion of approximately 32% of the cellulose, of which 2.4% was glucose, after the enzymatic hydrolysis reaction, suggesting that C. laurentii is a good ${\beta}$-glucosidase producer. The results presented in this study highlight the importance of isolating microbial strains that produce enzymes of biotechnological interest, given their extensive application in biofuel production.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.126-132
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• 2012

In recent years, serious environmental problems occur in coastal area due to high pollution loads from human activity in land. Marine biomass utilization system therefore has been proposed to prompt material circulation between land and sea. Comprehensive assessment is necessary to determine that the proposed system is suitable and sustainable. This study introduces thermodynamic concept exergy, which expresses energy quality, to describe material and energy flowing in the material circulation system. This study presents material, energy and exergy flows in the material circulation system at Sakai city located in the middle of Osaka in Japan. It is found that exergy helps a better understanding of what is a key role is in exergy-efficient material circulation system.

• Mycobiology
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• v.51 no.4
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• pp.230-238
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• 2023

Glabridin is a well-known active isoflavone found in the root of licorice (Glycyrrhiza glabra L.) that possess a wide range of biological activity. Plant cells, hairy roots, and fungal endophytes cultures are the most important alternative methods for plant resources conservation and sustainable production of natural compounds, which has received much attention in recent decades. In the present study, an efficient culture condition was optimized for the biomass accumulation and glabridin production from fungal endophyte Aspergillus eucalypticola SBU-11AE isolated from licorice root. Type of culture medium, range of pH, and licorice root extract (as an elicitor) were tested. The results showed that the highest and lowest biomass production was observed on PCB medium (6.43 ± 0.32 g/l) and peptone malt (5.85 + 0.11 g/l), respectively. The medium culture PCB was produced the highest level of glabridin (7.26 ± 0.44 mg/l), while the lowest level (4.47 ± 0.02 mg/l) was obtained from the medium peptone malt. The highest biomass (8.51 ± 0.43 g/l) and glabridin (8.30 ± 0.51 mg/l) production were observed from the PCB medium adjusted with pH = 6, while the lowest value of both traits was obtained from the same medium with pH = 7. The highest production of total glabridin (10.85 ± 0.84 mg/l) was also obtained from the culture medium treated with 100 mg/l of the plant root extract. This information can be interestingly used for the commercialization of glabridin production for further industrial applications.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.231-243
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• 2014

In this study, the potential of biomass, which is generated from oil palm cultivation and crude palm oil (CPO) production of Indonesia was assessed in the aspect of energy content. The types of oil palm biomass were classified on the basis of the cultivation stage and the CPO production stage. In the cultivation stage, biomass is considered to be produced from its' root, trunk and frond. Other possible biomass resources such as empty fruit bunch (EFB), palm kernel shell (PKS) and fiber were included in the CPO production stage. As results, total biomass from damaged plantation area of Indonesia was estimated to be annually from 3 million to 16 million tons in 2011. From CPO mills, approximately 49 million tons/yr of biomass residues were estimated to be annually occurred. Their total energy content from each biomass source in cultivation stage was analyzed to be from 593,000 to 3,197,000 TOEs in terms of gross calorific value. In the case of CPO mills, around 22.7 million TOEs was estimated to be potential energy producible by biomass based on gross calorific value of dry basis. If moisture content considered, net calorific value was analyzed to be decreased to 16.3 million TOEs. Based on the results, the total energy contents of all oil palm biomass were estimated to be up to 25,919,000 TOE in terms of gross calorific value. CPO : Crude Palm Oil, EFB : Empty Fruit Bunch, FFB: Fresh Fruit Bunch, PKS : Palm Kernel Shell, OPF : Oil Palm Frond, PKOC : Palm Kernel Oil Cake, ISPO : Indonesia Sustainable Palm Oil Commission, TOE : Tone of Oil Equivalent.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1286-1294
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• 2011

This paper reviews the future directions and perspectives on the soil environmental researches in the 21 century. Previously, the principal emphasis of soil environmental researches had put on the enhancement of food and fiber productions. Beside the basic function of soil, however, the societal needs on soil resources in the 21st century have demands for several environmental and social challenges, occurring regionally or globally. Typical global issues with which soil science should deal include food security with increasing agronomic production to meet the exploding world population growth, adaptation and mitigation of climate change, increase of the carbon sequestration, supply of the biomass and bioenergy, securing the water resource and quality, protection of environmental pollution, enhancing the biodiversity and ecosystem health, and developing the sustainable farming/cropping system that improve the use efficiency of water and agricultural resources. These challenges can be solved through the sustainable crop production intensification (SCPI) or plant welfare concept in which soil plays a key role in solving the abovementioned global issues. Through implementation of either concept, soil science can fulfill the goal of the modern agriculture which is the sustainable production of crops while maintaining or enhancing the ecosystem function, quality and health. Therefore, directions of the future soil environmental researches should lie on valuing soil as an ecosystem services, translating research across both temporal and spatial scales, sharing and using data already available for other purposes, incorporating existing and new technologies from other disciplines, collaborating across discipline, and translating soil research into information for stakeholders and end users. Through the outcomes of these approaches, soil can enhance the productivity from the same confined land, increase profitability, conserve natural resource, reduce the negative impact on environment, enhance human nutrition and health, and enhance natural capital and the flow of ecosystem services. Soil is the central dogma, final frontier and new engine for the era of sustainability development in the $21^{st}$ century and thus soil environmental researches should be carried according to this main theme.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.340-360
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• 2010

The depletion of fossil fuels, ecological problems associated with $CO_2$ emissions climate change, growing world population, and future energy supplies are forcing the development of alternative resources for energy (heat and electricity), transport fuels and chemicals: the replacement of fossil resources with $CO_2$ neutral biomass. Several options exist to cover energy supplies of the future, including solar, wind, and water power; however, chemical carbon source can get from biomass only. When used in combination with environmental friend production and processing technology, the use of biomass can be seen as a sustainable alternative to conventional chemical feedstocks. The biorefinery concept is analogous to today's petroleum refinery, which produce multiple fuels and chemical products from petroleum. A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, and value-added chemicals from biomass. Biorefinery is the co-production of a spectrum of bio-based products (food, feed, materials, and chemicals) and energy (fuels, power, and heat) from biomass [definition IEA Bioenergy Task 42]. By producing multiple products, a biorefinery takes advantage of the various components in biomass and their intermediates therefore maximizing the value derived from the biomass feedstocks. A biorefinery could, for example, produce one or several low-volume, but high-value, chemical or nutraceutical products and a low-value, but high-volume liquid transportation fuel such as biodiesel or bioethanol. Future biorefinery may play a major role in producing chemicals and materials as a bridge between agriculture and chemistry that are traditionally produced from petroleum. Industrial biotechnology is expected to significantly complement or replace the current petroleum-based industry and to play an important role.

• The Journal of Fisheries Business Administration
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• v.23 no.2
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• pp.53-67
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• 1992

It has been recognized, virtually from the time of its inception, that fisheries economics, like other aspects of resource economics, should ideally be cast in capital-theoretic terms. The fish population or biomass can be viewed as a capital stock in that, like conventional or man-made capital, it is capable of yielding a sustainable consumption flow through time. This study is to introduce the optimal control theory which was extended from the theory of calculus of variations into the study of former static theory of fisheries economics started by Gordon (1954). The optimal control theory eliminated the inadequacies of the classical techniques to a large extent. From this point of view, this study, on the base of Schaefer model, summerizes most of major results achieved so far, but does so in a manner such that the links with capital theory are made transparent. This study explores two sets of problems. The first concerns the optimal approach to the equilibrium stock, i.e. the optimal investment policy. The second set of problems arises from the relaxation of the highly restrictive assumption of autonomy (i.e. the assumption that the parameters are independent of time), then concludes the relaxation of linearity assumption together with the complexities caused by that.

• Environmental Engineering Research
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• v.21 no.3
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• pp.265-275
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• 2016

In this study, the microalga Neochloris oleoabundans was cultivated in a sustainable manner using diluted anaerobic digestate to produce biomass as a potential biofuel feedstock. Prior to microalgae cultivation, the anaerobic digestate was characterized and several pretreatment methods including hydrogen peroxide treatment, filtration, and supernatant extraction were investigated and their impact on the removal of suspended solids as well as other organic and inorganic matter was evaluated. It was found that the supernatant extraction was the most convenient pretreatment method and was used afterwards to prepare the nutrient media for microalgae cultivation. A bench-scale experiment was conducted using multiple dilutions of the supernatant and filtered anaerobic digestate in 16 mm round glass vials. The results indicated that the highest growth of the microalga N. oleoabundans was achieved with a total nitrogen concentration of 100 mg N/L in the 2.29% diluted supernatant in comparison to the filtered digestate and other dilutions.