• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.92-98
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• 2013

Microalgal cultivation using wastewater is now regarded as essential for biodiesel production, as two goals can be achieved simultaneously; that is, nutrient removal efficiency and biomass production. Therefore, this study examined the effects of carbon sources, the N:P ratio, and the hydraulic retention time (HRT) to identify the optimal conditions for nutrient removal efficiency and biomass production. The effluent from a 2nd lagoon was used to cultivate microalgae. Whereas the algal species diversity and lipid content increased with a longer HRT, the algal biomass productivity decreased. Different carbon sources also affected the algal species composition. Diatoms were dominant with an increased pH when bicarbonate was supplied. However, 2% $CO_2$ gas led to a lower pH and the dominance of filamentous green algae with a much lower biomass productivity. Among the experiments, the highest chlorophyll-a concentration and lipid productivity were obtained with the addition of phosphate up to 0.5 mg/l P, since phosphorus was in short supply compared with nitrogen. The N and P removal efficiencies were also higher with a balanced N:P ratio, based on the addition of phosphate. Thus, optimizing the N:P ratio for the dominant algae could be critical in attaining higher algal growth, lipid productivity, and nutrient removal efficiency.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.447-458
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• 2012

This study was carried out to evaluation of biomass generation mechanisms and to propose the estimation method of biomass generation. Agricultural by-product biomass is generated during crops cultivation and after harvest. However these are not uniformly generated yearly and these depending on the seasons. For planning of biomass utilization, accurate information of the biomass resources is needed, especially characteristic and productivity of biomass are necessary. Agricultural by-product biomass are generated in a wide area being scattered and it is one of the major reason why agricultural biomass utilization is not activated compared with other waste biomass. In this study, estimation and evaluation biomass generation is achieved in specific spatial and temporal boundary, A-city in Gyeongi-do and september to November respectively. Quantity and quality of by-product biomass show big difference depending on the crop species and cultivation periods and these difference bring up that accurate biomass estimation should be considered during planning of biomass utilization and technology selecting for biomass converting to energy and other forms.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.234-242
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• 2011

BACKGROUND: Cultivation of winter cover crops is strongly recommended to increase land utilization efficiency, animal feeding material self-production, and to improve soil and environmental quality. METHODS AND RESULTS: Four major winter crops (barley, Chinese milk vetch, hairy vetch, and rye) having different C/N ratio were seeded in silt loam paddy soil in the November 2007 and the aboveground biomass was harvested on the late May 2008 to evaluate its effectiveness as green manure, and root biomass distribution was characterized at the different depth (0-60 cm) to study its effect on physical properties and carbon sequestration in soil. During this experiment, the naturally growing weed in the rice paddy soil in Korea, short awn foxtail (Alopecurus aequalis Sobol), was considered as control treatment. Above-ground biomass of all cover crops selected was significantly higher than that of the control treatment (2.8 Mg/ha). Comparatively higher above-ground biomass productivity of rye and barley (15.8 and 13.5 Mg/ha, respectively) suggested that these cover crops possibly had the highest potential as a green manure and animal feeding material. Root biomass production of different cover crops followed the same trend as that for their above ground biomass. Rye (Secale cereal) might have the highest potential for soil C accumulation (7893 C kg/ha) by root biomass development, and then followed by barley (6985 C kg/ha), hairy vetch (6467 C kg/ha), Chinese milk vetch (6671 C kg/ha), and control (5791 C kg/ha). CONCLUSION(s): Cover crops like rye and barley having high biomass productivity might be the most effective winter cover crops to increase organic carbon distribution in different soil aggregates which might be beneficial to improve soil structure, aeration etc. and C sequestration.

• Microbiology and Biotechnology Letters
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• v.23 no.4
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• pp.479-484
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• 1995

The effect of initial cell concentration on the characteristics of ethanol fermentation was investigated in the batch fermentation of Saccharomyces cerevisiae ATCC 24858. The characteristics were investigated in the range of 60 to 230 g/l of the initial sugar concentrations and 0.5 to 85 g/l of the initial cell concentrations. When the initial cell concentrations were 27 g/l for 60 g/l of the initial sugar and 85 g/l for 230 g/l, the fermentation time required for the complete consumption of the initial sugar was one hour, respectively. The ethanol productivity increased with the initial cell concentration so that, in the case of 100 g/l of initial sugar, the productivity rose up to 55 g/l/hr at 55 g/l of the initial cell concentration. The specific growth rate decreased according to the increase in the initial biomass concentration and finally became zero at around 25 g/l of the cell concentration regardless of the initial sugar concentration. The specific ethanol production rate was constant as 1.02 g/l/hr up to 150 g/l of the initial sugar. However, the rates decreased sharply with the augmentation of concentration of the initial sugar above 160 g/l. The overall ethanol yield represented a constant value, 0.475 g/g irrespective of the initial cell and sugar concentrations. The overall biomass yietd showed a trend to diminish in values with the biomass and ultimately to reach zero more than 25 g/l of the initial cell concentration.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.24-29
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• 2016

Microalgae are considered as superior biodiesel producers, because they could effectively produce high amount of lipid with fast growth rate. In this study, Chlorella vulgaris was exposed to various light wavelengths (${\lambda}_{max}$ 470 nm, ${\lambda}_{max}$ 525 nm, and ${\lambda}_{max}$ 660 nm) using light emitting diodes (LEDs) to examine effect of light quality on their growth and fatty acid production in 0.4-L bubble column photobioreactors. Fluorescent lamps were also used as polychromatic light sources (control). From the results, biomass productivity was varied by light wavelength from 0.05 g/L/day to 0.30 g/L/day. Maximum biomass productivity was obtained from red LED among tested ones. We also observed that contents of oleic acid and linolenic acid, which affect biodiesel properties, were significantly changed depending on supplied wavelength. These results indicated that production of algal biomass, and fatty acid content and productivity could be improved or controlled by supplying specific light wavelength.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1434-1443
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• 2019

Although chemical oxygen demand (COD) is an important issue for wastewater treatment, COD reduction with microalgae has been less studied compared to nitrogen or phosphorus removal. COD removal is not efficient in conventional wastewater treatment using microalgae, because the algae release organic compounds, thereby finally increasing the COD level. This study focused on enhancing COD removal and meeting the effluent standard for discharge by optimizing sludge inoculation timing, which was an important factor in forming a desirable algae/bacteria consortium for more efficient COD removal and higher biomass productivity. Activated sludge has been added to reduce COD in many studies, but its inoculation was done at the start of cultivation. However, when the sludge was added after 3 days of cultivation, at which point the COD concentration started to increase again, the algal growth and biomass productivity were higher than those of the initial sludge inoculation and control (without sludge). Algal and bacterial cell numbers measured by qPCR were also higher with sludge inoculation at 3 days later. In a semi-continuous cultivation system, a hydraulic retention time of 5 days with sludge inoculation resulted in the highest biomass productivity and N/P removal. This study achieved a further improved COD removal than the conventional microalgal wastewater treatment, by introducing bacteria in activated sludge at optimized timing.

• Journal of Korean Society of Forest Science
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• v.106 no.1
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• pp.54-62
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• 2017

This study was carried to develop the chip-harvester and to analysis the operation productivity and cost for effective collection and forwarding of forest biomass. Main target specification of chip-harvester is speed of 8km/h, maximum climbing capacity of $30^{\circ}$ and maximum load capability of 2000 kg. Body structure is articulate type to reduce turning radius. Driving equipment is six-wheel drive, and a rear wheel is tandem bogie type to increase grip force. As a result of the driving test about developed chip-harvester, driving speed was 6.9 km/hr and 8.1 km/hr in ${\pm}10%$ slope with loaded and 7.3 km/hr and 7.9 km/hr in ${\pm}10%$ slope without load. As a result of the operation productivity and cost, operation productivity of grinding and forwarding was approximately $10m^3$ per day, and operation cost was 393,126 won per day.

• Mycobiology
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• v.30 no.3
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• pp.166-169
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• 2002

Protein productivity by the cellulolytic fungi, Trichoderma viride(MTCC 800), Chaetomium globosum and Aspergillus terreus was compared in co-culture and mixed culture fermentations of cashewnut bran. Co-cultures were more effective in substrate saccharification, which ranged between $85{\sim}88%$ compared to the $62{\sim}67%$ saccharification shown by the monocultures. Maximum saccharification was induced by T. viride and C. globosum co-culture resulting in the highest 34% release of reducing sugars. The maximum 16.4% biomass protein and the highest protein productivity(0.58%) were shown by T. viride and A. terreus co-culture. A. terreus performed better in co-culture in the presence of T. viride rather than with C. globosum. Among the cellulolytic enzymes, FPase(Filter Paper Cellulase) activity was significantly higher in all the co-cultures and in the mixed culture than in their respective monocultures. Mixed culture fermentation involving all the three fungi was not effective in increasing the per cent saccharification or the biomass protein content over the co-cultures.

• Journal of Plant Biology
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• v.18 no.3
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• pp.122-128
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• 1975

With the cultivated mulberry plant which feeds silkworm on its leaves in sericulture, the measuring methods of biomass of terrestrial organs were compared and the annual net productivity was estimated. The measurement of the standing crops by means of allometric method on basis of relation between the parameter D230H, square of the diameter of the branch on 30cm high above ground($D{\frac}{2}{30}$) multiplied by its height(H), and the amount of leaves(WL) or of branch (Ws) was more accurate than other methods on basis of correlation between a character of the branch such as H, D30 or D230 and WL or Ws. The estimate of value of the net productivity of terrestrial parts of mulberry was 9.06-12.54 ton/ha.year, which was similar to that obtained from secondary forests in cool temperate zone.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2019-2028
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• 2018

Natural astaxanthin mainly derives from a microalgae producer, Haematococcus pluvialis. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production. However, the different responses to light intensity and nitrogen starvation needed to be analyzed for biomass growth and astaxanthin accumulation. The results showed that the highest level of astaxanthin production was achieved in nitrogen starvation, and was 1.64 times higher than the control group at 11 days. With regard to the optimization of light intensity utilization, it was at $200{\mu}mo/m^2/s$ under nitrogen starvation that the highest astaxanthin productivity per light intensity was achieved. In addition, both high light intensity and a nitrogen source had significant effects on multiple indicators. For example, high light intensity had a greater significant effect than a nitrogen source on biomass dry weight, astaxanthin yield and astaxanthin productivity; in contrast, nitrogen starvation was more beneficial for enhancing astaxanthin content per dry weight biomass. The data indicate that high light intensity synergizes with nitrogen starvation to stimulate the biosynthesis of astaxanthin.