• Journal of Ecology and Environment
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• v.38 no.1
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• pp.67-74
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• 2015

Three strains of the green microalga Botryococcus braunii (JJS, KCM, and KJD) were isolated from different water bodies in Korea and grown as batch cultures in the laboratory. The effects of different growth media and temperatures on the growth rate were investigated, as well as the effect of temperature on the total lipid content and lipid profile. All three strains had the highest growth rates in BG-11 medium and at $25^{\circ}C$. Maximal lipid production ($gL^{-1}$) was at $30^{\circ}C$ in the JJS strain and at $25^{\circ}C$ in the KCM and KJD strains. However, all the three strains produced the greatest percent dry weight of total lipids at $15^{\circ}C$ and had the lowest percent dry weight of total lipids at $25^{\circ}C$. In general, oleic acid, linolenic acid, and behenic acid were the most common fatty acids in all three strains. However, the three strains varied considerably in their fatty acid profiles at different culture temperatures.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1250-1256
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• 2023

Herein, different extracts of Scenedesmus deserticola JD052, a green microalga, were evaluated in vitro as a potential anti-aging bioagent. Although post-treatment of microalgal culture with either UV irradiation or high light illumination did not lead to a substantial difference in the effectiveness of microalgal extracts as a potential anti-UV agent, the results indicated the presence of a highly potent compound in ethyl acetate extract with more than 20% increase in the cellular viability of normal human dermal fibroblasts (nHDFs) compared with the negative control amended with DMSO. The subsequent fractionation of the ethyl acetate extract led to two bioactive fractions with high anti-UV property; one of the fractions was further separated down to a single compound. While electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy analysis identified this single compound as loliolide, its identification has been rarely reported in microalgae previously, prompting thorough systematic investigations into this novel compound for the nascent microalgal industry.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.328-336
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• 2020

Parachlorella sp. is an efficient fatty acid producer that can be used in the production of biofuels, feeds, and fertilizers. Microalgae show varying responses to culture conditions, even those within the same species. In this study, growth and fatty acid composition of a newly isolated Parachlorella sp. from the Nakdong river of Korea in different culture media were investigated. The microalga was cultivated in 400 ml bubble column photobioreactors using BG-11, BBM, TAP, and modified TAP (MTAP) media. It was shown that using BBM led to greater fatty acid accumulation (34%), while using TAP medium led to greater biomass productivity (0.34 g/l/day). Composition of the TAP medium was modified to have the N:P ratio of BBM while also varying concentrations of N and P to improve fatty acid productivity. One of the modified TAP media, MTAP-1 (104.8 mgN/l, 135.2 mgP/l, N:P ratio = 0.77), showed the highest fatty acid concentration of 0.69 ± 0.04 g/l, while those from TAP and BBM were 0.48 ± 0.06 g/l and 0.40 ± 0.02 g/l, respectively. The results showed that microalgal fatty acid productivity could be enhanced by changing the N:P ratio and concentrations.

• Korean Journal of Poultry Science
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• v.47 no.1
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• pp.49-59
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• 2020

The present study determined the effect of dietary cultivated microalgae (Parachlorella sp.) on the growth and immune responses of pre-starter broilers. A total of 320 one-day-old birds (Ross 308) were allocated to 4 treatments with 8 blocks in a randomized complete block design. The four experimental diets consisted of a corn-soybean meal-based control diet, and three diets contained 0.5%, 1.0%, and 1.5% microalgae powder at the expense of cornstarch in the control diet. After feeding the experimental diets for 7 days, the body weight and feed intake of all birds were measured, and 8 birds were randomly selected from each treatment. Peripheral blood mononuclear cells (PBMCs) and serum were harvested for immune profile assessment, including cytokines and cell migration receptors. No differences in growth performance were observed among the treatments. The birds that were fed diets containing graded levels of microalga showed a linear increase in the mRNA expression of cytokine genes in PBMCs, including that of IL2, IL1β, and IL18 (P<0.05). With respect to the chemokine receptor genes in PBMCs, mRNA expression of CCR2, CCR9, and ITGA4 changed quadratically (P<0.05), but that of CCR7 increased linearly (P<0.01). Cytokine protein secretion in blood, including that of IL-1β and IL-6, increased linearly (P<0.01) with an increase in the microalgal content. Overall, the present results show that the indigenous microalgae powder used in this study could stimulate immunity with no detrimental effects on the growth performance of pre-starter broiler chickens.

• Journal of Marine Bioscience and Biotechnology
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• v.15 no.2
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• pp.41-48
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• 2023

The objective of the present study was to improve the biomass productivity of newly isolated freshwater green microalga Parachlorella sp. This was accomplished by culture conditions optimization, including CO₂ concentration, superficial gas velocity, and light intensity, in 0.5 L bubble column photobioreactors. The supplied CO₂ concentration and gas velocity varied from 0.032% (air) to 10% and 0.02 m/s - 0.11 m/s, respectively, to evaluate their effects on growth kinetics. Next, to maximize the production rate of Parachlorella sp., a lumostatic operation based on a specific light uptake rate (q_e) was applied. From these results, the optimal CO₂ concentration in the supplied gas and the gas velocity were determined to be 5% and 0.064 m/s, respectively. For the lumostatic operation at 10.2 µmol/g/s, biomass productivity and photon yield showed significant increases of 83% and 66%, respectively, relative to cultures under constant light intensity. These results indicate that the biomass productivity of Parachlorella sp. can be improved by optimizing gas properties and light control as cell concentrations vary over time.

• KSBB Journal
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• v.14 no.3
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• pp.328-336
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• 1999

A green microalga, Chlorella vulgaris UTX 259, was cultivated in a bench-scale raceway pond. During the culture, 15%(v/v) $CO_2$ was supplied and industrial wastewater discharged from a steel-making plant was used as a culture medium. In a small scale culture bottle, the microalga grew up to 1.8 g $dm^{-3}$ of cell concentration and ammonia was completely removed from the wastewater with an yield coefficient of 25.7 g dry cell weight $g^{-1}\;NH_3-N$. During the bottle-culture, microalga was dominant over heterotrophic microorganisms in the culture medium. Therefore, the amount of carbon dioxide fixation could be estimated from the change of dry cell weight. In a semi-continuous operation of raceway pond with intermittent lighting (12 h light and 12 h dark), increase of dilution rate resulted in increase of the ammonia removal rate as well as the $CO_2$ fixation rate but the ammonia removal efficiency decreased. Ammonia was not completely removed from the medium (wastewater) of raceway pond which was operated in a batch mode under a light intensity up to 20 klux. The incomplete removal of ammonia was believed due to insufficient light supply. A mathematical model, capable of predicting experimental data, was developed in order to simulate the performance of the raceway pond under the light intensity of sun during a bright daytime. Simulation results showed that the rates of $CO_2$ fixation and ammonia removal could be enhanced by increasing light intensity. According to the simulation, 80 mg $dm^{-3}$ of ammonia in the medium could be completely removed if the light intensity was over 60 klux with a continuous lighting. Under the optimal operating condition determined by the simulation, the rates of carbon dioxide fixation and ammonia removal in the outdoor operation of raceway pond were estimated as high as $24.7 g m^{-2} day^{-1}$ and $0.52 g NH_3-N m^{-2} day^{-1}$, respectively.

• Journal of Life Science
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• v.27 no.10
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• pp.1152-1160
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• 2017

A unicellular green alga was axenically isolated from a tidal pool on Ulleung-do, Korea. Morphological, molecular, and biochemical analyses revealed that the isolate belonged to Auxenochlorella protothecoides. The current study is the first record of this species in Korea. The microalgal strain was named as A. protothecoides MM0011 and its growth, lipid and pigment compositions, and biomass properties were investigated. The strain is able to thrive in a wide range of temperatures ($5{\sim}35^{\circ}C$) and to withstand up to 1.5 M NaCl. The results of GC/MS analysis showed that the isolate was rich in nutritionally important polyunsaturated fatty acids (PUFAs). Its major fatty acids were linoleic acid (27.6%) and ${\alpha}-linolenic$ acid (39.6%). Thus, this indigenous microalga has potential as an alternative source of ${\omega}3$ and ${\omega}6$ PUFAs, which currently come from fish and plant oils. Also, the HPLC analysis revealed that the value-added antioxidant, lutein, was biosynthesized as the accessory pigments by the microalga. A proximate analysis showed that the volatile matter content was 85.6% and an ultimate analysis indicated that the gross calorific value was $20.3MJ\;kg^{-1}$. Since 40.5% of total nitrogen and 27.9% of total phosphorus were removed from the medium, respectively, it also has potential as a feedstock for biofuel applications which could be coupled to wastewater treatment. In addition, the biomass may also serve as an excellent animal feed because of its high protein content (51.4%). Therefore, A. protothecoides MM0011 shows promise for application in production of microalgae-based biochemicals and as a biomass feedstock.

• 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.

• ALGAE
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• v.27 no.4
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• pp.295-301
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• 2012

Carbon concentrating mechanisms play a vital role in photosynthesis in microalgae and cyanobacteria especially in the proper functioning of Rubisco and assimilation of carbon via the Calvin cycle. This study evaluates the role of carbon dioxide on carbon concentrating mechanism (CCM) in a cynaobacteria, Spirulina platensis and a microalga, Chlorella sp. 786. The study organisms were grown in both atmospheric (control sample, 0.035%) and high (exposed sample, 10%) $CO_2$ concentrations. Second dimension (2D) electrophoresis revealed a huge difference in the protein profiles of both organisms suggesting the induction of CCM related proteins in the sample maintained at atmospheric $CO_2$ concentration and the repression of CCM related proteins in the sample maintained at 10% $CO_2$. Liquid chromatography-mass spectroscopy analysis revealed the presence of two important $C_i$ transporter proteins in the control sample of S. platensis, namely ferredoxin-$NADP^+$ reductase and ATP binding cassette (ABC) transport system protein. These proteins were only expressed in the control sample and were downregulated or not expressed at all in the exposed sample. Consequently, this study conclusively proves that CCMs are only inducted at low $CO_2$ concentrations and are not functional at high $CO_2$ concentration.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1060-1066
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• 2005

Under environmental stress, such as strong irradiance or nitrogen deficiency, unicellular green algae of the genus Haematococcus accumulate secondary carotenoids, i.e. astaxanthin, in the cytosol. The induction and regulation of astaxanthin biosynthesis in microalgae has recently received considerable attention owing to the increasing use of secondary carotenoids as a source of pigmentation for fish aquacultures, and as a potential drug in cancer prevention as a free-radical quencher. Accordingly, this study generated expressed sequence tags (ESTs) from a library constructed from astaxanthin-induced Haematococcus pluvialis. Partial sequences were obtained from the 5' ends of 1,858 individual cDNAs, and then grouped into 1,025 non-overlapping sequences, among which 708 sequences were singletons, while the remainder fell into 317 clusters. Approximately $63\%$ of the EST sequences showed similarity to previously described sequences in public databases. H. pluvialis was found to consist of a relatively high percentage of genes involved in genetic information processing ($15\%$) and metabolism ($11\%$), whereas a relatively low percentage of sequences was involved in the signal transduction ($3\%$), structure ($2\%$), and environmental information process ($3\%$). In addition, a relatively large fraction of H. pluvialis sequences was classified as genes involved in photosynthesis ($9\%$) and cellular process ($9\%$). Based on this EST analysis, the full-length cDNA sequence for superoxide dismutase (SOD) of H. pluvialis was cloned, and the expression of this gene was investigated. The abundance of SOD changed substantially in response to different culture conditions, indicating the possible regulation of this gene in H. pluvialis.