• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.1
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• pp.30-37
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• 2016

Microalgae are functional foods because they contain special anti-aging inhibitors and other functional components, such as ecosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and omega-3 polyunsaturated fatty acids. Many of these functional dietary components are absent in animals and terrestrial plants. Thus, microalgae are widely utilized in human functional foods and in the feed provided to farmed fish and terrestrial livestock. Many marine organisms consume microalgae, often because they are in an appropriate portion of the cell size spectrum, but also because of their nutritional content. The nutritional requirements of marine organisms differ from those of terrestrial animals. After hatching, marine animals need small live forage species that have high omega-3 polyunsaturated fatty acid contents, including EPA and DHA. Euglena cells have both plant and animal characteristics; they are motile, elliptical in shape, 15-500 μm in diameter, and have a valuable nutritional content. Mixotrophic cell cultivation provided the best growth rates and nutritional content. Diverse carbon (fructose, lactose, glucose, maltose and sucrose) and nitrogen (tryptone, peptone, yeast extract, urea and sodium glutamate) supported the growth of microalgae with high lipid contents. We found that the best carbon and nitrogen sources for the production of high quality Euglena cells were glucose (10 g L^–1) and sodium glutamate (1.0 g L^–1), respectively.

• Korean Journal of Plant Tissue Culture
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• v.28 no.2
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• pp.91-95
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• 2001

Propagules grown at different in vitro culture conditions such as heterotrophic, mixotrophic and photoautotrophic conditions were investigated for growth, total photosynthesis ratio and flowering. Survival rate of propagules after transplanting was higher in photoautotrophic propagules than in the heterotrophic and mixotrophic ones. Total photosynthesis was higher plantlets growth in photoautotrophic (154 mg$CO_2$.mgDW$^{-1}$ h$^{-2}$ ) those grown than in mixotrphpic (148 mg$CO_2$.mgDW$^{-1}$ h$^{-2}$ ) and heterotrophic (102 mg$CO_2$.mgDW$^{-1}$ h$^{-2}$ ) 30 days after transplanting into fields. Day to flowering of the plant cultured in photoautotrophic condition was shortened by 7~10 days than those of heterotrophic and mixotrophic ones. Length of the petiole, number of leaves, leaf area and chlorophyll content were also increased.

• KSBB Journal
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• v.24 no.4
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• pp.377-382
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• 2009

The culture condition of growing Chlorella minutissima was optimized to produce biodiesel for fed-batch cultivation. First, under heterotrophic cultivation, the optimum level of glucose was determined to be 10 g/L for 20 days. After, three cultivation conditions were operated: autotrophic, heterotrophic, and mixotrophic growth. The lipid level and the maximum cell concentration from the fed-batch heterotrophic process were 32.0 (%, v/v) and 15.0 (g-dry wt./L) in 20 L flask, respectively. In addition, since the relatively constant specific lipid production rate was observed as 0.040 (% lipid/g-dry wt./day) at the latter period of cultivation time, the fed-batch process could maintain continuous lipid production. Fed-batch process is higher than those values from the batch process. The lipids from the fed-batch process contained over 38% of $C_{18}$, known as the suitable composition for the biodiesel application. For mixotrophic and heterotrophic growth under fed-batch condition, glucose was proved to be an appropriate carbon source for a large scale outdoor cultivation. For fed-batch cultivation, the feeding rate of seawater medium containing glucose was decided to be 0.5 L/day. The mixotrophic cultivation maintained maximum cell concentration of 24 (g-dry wt./L) and the lipid level of 43 (%, w/w). The lipid composition from this process was also proved to be suitable for the biodiesel production. The fatty acids from the mixotrophic growth contains 18% of $C_{17}$ and 49% of $C_{18}$, implying It also tells that C. minutissima is a suitable resource of biodiesel. Especially, the mixotrophic cultivation with fed-batch process might be useful for the large scale cultivation for the biodiesel production.

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.180.4-180
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• 2003

No Abstract, See Full Text

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.73-78
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• 2018

The main objective of this study was to evaluate the effects of acetate on the cultivation of anabena under mixotrophic condition. Four different types of acetates were used for the anebena cultivation. Among them, ethyl acetate was found to be the most effective and the growth rates linearly increased as the amount of ethyl acetate increased. When 40 mM of ethyl acetate was used, the highest values of specific growth rate of $0.979day^{-1}$ and maximum biomass productivity of $0.293g\;L^{-1}\;d^{-1}$ were obtained. On the contrary, input of acetic acid and butyl acetate inhibited the growth of anabena. For aeration tests, 0.54 vvm was optimum for anabena cultivation. For a semi-continuous cultivation test, ethyl acetate was used after 0.54 vvm test was finished. Then, test continued under 0.54 vvm and 40 mM of ethyl acetate. Lower specific growth rate and maximum biomass productivity were obtained compared to those from batch cultivation tests. However, the greatest maximum concentration of 5.91 g/L was obtained during the semi-continuous cultivation test.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.1
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• pp.38-44
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• 2016

The quality and quantity of live food sources strongly influence the success of fish production in farming operations. Thus, critical studies of live forage species are a crucial element for progress in fish aquaculture. The fat content of food is an especially important determinant of growth in marine fish. Omega-3 highly unsaturated fatty acids (HUFA) are essential components of diet that determine the nutritional value of larval fish. Euglena is a protist that has potential as a forage species. These single-celled organisms have plant and animal characteristics they are motile, elliptical in shape and 15–500 μm in diameter. Their nutritional content is excellent, but most studies have focused on cells raised in autotrophic culture. We therefore examined differences in the lipid and fatty acid contents, and the growth of Euglena cells grown under autotrophic, heterotrophic, and mixotrophic conditions. Biomass production reached 15.03 g/L, 12.28 g/L, and 3.66 g/L under mixotrophy, heterotrophy, and autotrophy, respectively. The proportional n-3 HUFA content differed among culture methods: 10.04%, 5.80% and 10.01% in mixotrophic, heterotrophic and autotrophic cultures, respectively. Mixotrophy was to be the best form of cultivation for improving the growth and nutritional content of Euglena.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.69-76
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• 2013

Specific growth rate and removal rate of nitrogen and phosphorus of Chlorella sorokiniana, Chlorella vulgaris, Senedesmus dimorphus those are able to metabolite mixotrophically and have high nitrogen and phosphorus removal capacity were examined. Based on the results, one microalgae was selected and conducted experiments to identify the operating factors such as pH and aeration rate. The specific growth rate and phosphorus removal rate of C. sorokiniana significantly presented as $0.29day^{-1}$ and 1.65 mg-P/L/day, while the nitrogen removal rate was high as 12.7 mg-N/L with C. vulgaris. C. sorokiniana was chosen for appropriate microalgae to applying for wastewater treatment system and was cultured in pH ranged 3 to 11. High specific growth rate and removal rate of nitrogen and phosphorus were shown at pH 7 as $0.71day^{-1}$, 7.61 mg-N/L/day, and 1.24 mg-P/L/day, respectively. The specific growth rate examined with aeration rate between 0 and 2 vvm (vol/vol-min) highly presented as $1.2day^{-1}$ with 1.5 ~ 2 vvm, while the nitrogen removal rate was elevated with 0.5 vvm as 9.43 mg-N/L/day.

• Environmental Engineering Research
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• v.24 no.2
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• pp.271-278
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• 2019

Mass cultivation of microalgae is necessary to achieve economically feasible production of microalgal biodiesel. However, the high cost of nutrients is a major limitation. In this study, corncob extract (CCE) was used as an inorganic and organic nutrient source for the mass cultivation of Chlorella vulgaris (C. vulgaris). Chemical composition analysis of CCE revealed that it contained sufficient nutrients for mixotrophic cultivation of C. vulgaris. The highest specific grow rate of C. vulgaris was obtained at pH of 7-8, temperature of $25-30^{\circ}C$, and CCE amount of 5 g/L. In the analysis using various growth models, Luong model was found to be the most suitable empirical formula for mass cultivation of C. vulgaris using CCE. Analysis of biomass and production of triacyglycerol showed that microalgae grown in CCE medium produced more than 17.23% and 3% more unsaturated fatty acids than cells cultured in Jaworski's Medium. These results suggest that growing microalgae in CCE-supplemented medium can increase lipid production. Therefore, CCE, agricultural byproduct, has potential use for mass cultivation of microalgae.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.337-343
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• 2020

In this study, the medium optimization for cell growth and metabolite formation of Haematococcus sp. under mixotrophic cultivation was investigated. As a result, modified MS medium was selected as the basal medium; glucose was selected as the carbon source, with an optimum concentration of 10 g/l, and potassium nitrate was chosen as the nitrogen source, with an optimum concentration of 1.9 g/l. Under optimum conditions, Haematococcus sp. demonstrated an increase in biomass concentration from 0.18 gDW/l to 5.58 gDW/l in 14 days, after which there was a 31-fold increase in its growth. At the same time, the concentrations of chlorophyll and carotenoids were 172.16 mg/l and 42.33 mg/l, respectively. This work will contribute to the basic data for mass cultivation of microalgae.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.539-544
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• 2008

A mutant of Arthrospira platensis PCC 9108, strain M9108, obtained by mutagenesis with UV treatment, was able to mixotrophically grow in an SOT medium containing 40 g of glucose/l. The biomass and specific growth rate of strain M9108 (4.10 g/l and 0.70/d) were 1.9-fold and 1.4-fold higher, respectively, than those of the wild type (2.21 g/l and 0.58/d) under mixotrophic culture condition. In addition, when compared with the wild type, the content of ${\gamma}$-linolenic acid (GLA) in the mutant was increased when glucose concentration was increased. Compared with the wild type, the GLA content of the mutant was 2-fold higher in autotrophic culture and about 3-fold higher in mixotrophic culture. Thus, the mutant appears to possess more efficient facility to assimilate and metabolize glucose and to produce more GLA than its wild-type strain.