• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.381-389
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• 2019

Chlorella vulgaris was isolated from the Nile River, Qalubia Governorate, Egypt, for possible use in biodiesel production. BG-II nutrient growth media was used for isolation and laboratory growth. Identification was performed via 18S rRNA gene amplification, followed by sequencing. The alga was exposed to UV-C (254 nm) for 15, 30, and 45 s to improve dry weight accumulation and to increase the oil production. Daily measurements of dry weight ($g{\cdot}l^{-1}$) were performed; oil content and volumetric lipid productivity were also determined. UV-C exposure led to an increase in the volumetric lipid productivity by 27, 27.3, and $32.4mg{\cdot}l^{-1}{\cdot}d^{-1}$ with 15, 30, and 45 s, respectively, as compared with the control, which resulted in $18mg{\cdot}l^{-1}{\cdot}d^{-1}$. Of the examined mutants, the one with the highest productivity was re-irradiated by UV-C (254 nm) for 15, 30, 45, and 60 s. For 15 s of exposure time, the oil content increased to 34%, while it was 31% at 30 s; further, it decreased to 22% at 45 and 60 s exposures. The fatty acid methyl ester profile was 82.22% in the first mutant at 45 s, compared with the wild strain that contained a total of 66.01% of FAs. Furthermore, the highest levels of polyunsaturated fatty acid methyl ester were observed in the mutant exposed for 45 s, and it reached 11.41%, which reduced the cetane number to 71.3.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.522-528
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• 2016

In this study, we investigated the possibility of using hydrolysates of lignocellulosics (rapeseed straw, barley straw, rice straw) and marine macro-algae (Undaria pinnatifida, Laminaria japonica, Enteromorpha intestinalis, and Gracilaria verrucosa) to cultivate Chlorella saccharophila. The growth of C. saccharophila was inhibited by 7 hydrolysates without active carbon treatment. In contrast, hydrolysates treated with active carbon increased the cell growth and product (oil and chlorophyll) formation by C. saccharophila. The oil contents of C. saccharophila treated with each hydrolysate were $41.26{\pm}0.69%$ (glucose), $22.06{\pm}1.21%$ (rapeseed straw), $28.65{\pm}1.08%$ (barley straw), $31.15{\pm}0.76%$ (rice straw), $31.50{\pm}2.12%$ (U. pinnatifida), $31.49{\pm}4.53%$ (L. japonica), $29.63{\pm}3.93%$ (E. intestinalis), and $26.15{\pm}1.99%$ (G. verrucosa), respectively. Lignocellulosics and marine macro-algae may be useful resources for improving the mass cultivation of C. saccharophila.

• Molecular & Cellular Toxicology
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• v.5 no.1
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• pp.88-92
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• 2009

The effect of Chlorella vulgaris (CV) on the urinary excretion of di-ortho PCB congeners (PCB-138, -153) was investigated. Sprague-Dawley rats (6-weeks-old, n=10 rats/group) were randomly divided into one control (0CV) or 2% CV (2CV) or 5% CV (5CV) or 10% CV (10CV) groups, respectively. Composition of normal and chlorella meal-based diet were made up of 30% casein, 15% cornstarch, 50% sucrose, 5% cellulose, 5% coconut oil, 3.5% mineral mixture, 1 % vitamin mixture. All rats had free access to water and diet for 4 weeks. A significant increase in both PCB 138 and 153 in urinary level was detected in CV fed groups, 540% and 167% for 2CV, 155% and 89% for 5CV, 114% and 144% for 10CV group, respectively, when compared with their controls. These findings suggest that CV may have potential to eliminate body burden levels of dioxin-like PCB compounds.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.513-513
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• 2009

최근 바이오디젤의 원료로 미세조류가 많은 관심을 끌고 있다. 미세조류는 물, 이산화탄소와 태양광을 이용해 광합성 성장이 가능하며, 지질(오일) 성분이 풍부하여 바이오디젤의 원료로 이용할 수 있다. 미세조류는 단위 면적당 오일 생산량이 곡물류의 50-100배 이상이며, 이산화탄소를 기질로 이용하므로 온실가스 직접 저감이 가능하다. 또한 배양시 비경작지나 황무지를 사용할 수 있으므로 기존 식용작물과 경쟁하지 않으며, 하수, 해수, 폐수 등 다양한 물자원을 이용할 수 있다. 본 연구에서는 고농도 $CO_2$에 내성을 지닌 Chlorella sp. KR-1을 대상으로 1 L 규모 기포탑 광생물반응기에서 균체 성장 및 지질(바이오오일) 합성에 대한 $CO_2$ 농도, 가스 공급속도, 질산염 농도 등 환경 및 영향 조건의 영향을 조사하였다. 가스 공급속도 0.4 L/min에서 $CO_2$ 농도를 0.03-20% 범위에서 조사하였을 때 최대 균체성장은 $CO_2$ 10%에서 관찰되었다. 균체내 지방산 함량은 $CO_2$ 농도 0.03%에서 가장 낮았고, 5-20% 범위에서는 $CO_2$ 농도 증가에 따라 감소하는 경향이 관찰되었다. 가스 공급속도를 0.2 L/min에서 0.8 L/min으로 증가시켰을 때 최대 균체농도는 0.6-0.8 L/min의 범위에서 관찰되었고, 생체내 최대 지방산 함량은 0.4 L/min에서 관찰되었다. Nitrate 농도 1-20 mM 범위에서 최종 균체농도는 nitrate 농도 증가에 따라 10mM까지 증가하였으나 그 이상에서는 증가하지 않았다. 반면 지방산 함량은 nitrate 농도 증가에 따라 감소하는 경향이 관찰되었다. 본 실험에서 얻은 최대 지방산 생산량은 1,100 mg/L이었으며, 주요 지방산은 C10:0(1.7%), C16:0(28.5%), C18:0(11%), C18:1n9c(25.9%), C18:2n6c(26.3%), C18:3n3(6.6%)이었다. 현재 100 L 규모 광생물반응기에서 석탄발전소 배가스($CO_2$ 12-15%, SOx 50ppm, NOx 100ppm)를 이용한 바이오오일 생산 실험이 진행 중이다.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.672-677
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• 2012

Lipids in microalgal biomass were recovered by using pyrolysis method. The pyrolysis experiments of two Chlorella sp. KR-1 samples, which have triglyceride contents of 10.8% and 36.5%, respectively were carried out at $600^{\circ}C$ to investigate the effects of lipid contents in the cells on the reaction characteristics. The conversion and liquid yield of the lipid-rich sample were higher than those of the lipid-lean sample since its carbon to hydrogen ratio was low. There were low molecular weight organic acids, ketones, aldehydes and alcohols in the liquid products from both KR-1 samples, but the pyrolysis oil of the lipid-rich sample was abundant in free fatty acids, particularly palmitic acid, oleic acid and stearic acid while the content of nitrogen containing organic compounds was low. The microalgal pyrolysis oil had two layers composed of the light hydrophobic fraction and the heavy hydrophilic fraction. The light fraction might be originated from triglycerides and the heavy fraction might be from carbohydrates and proteins. In the light fraction of the liquid products, there were considerable linear alkanes such as pentadecane and heptadecane as well as free fatty acids, implying that deoxygenation reaction including decarboxylation was occurred during the pyrolysis. The yield of the liquid products from the pyrolysis of the KR-1 sample having triglyceride content of 36.5% was 56.9% and the light fraction in the liquid products was 68.2%. Also more than 80% of the light fraction was free fatty acids and pure hydrocarbons, thus showing that most triglycerides could be extracted in the form of suitable raw materials for biofuels.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.288-289
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• 2000

양식산업에서 널리 이용되는 rotifer와 같은 먹이생물의 고도 불포화지방산 (n-3 HUFA)함량은 양식 초기의 치자어의 정상적인 생존 및 성장을 위해서 필수적이다. 그러나 담수산 농축 Chlorella를 이용하여 대량 배양한 rotifer들은 고도 불포화 지방산 함량이 낮아 해산 어류 자어에 먹이로 공급시 문제점으로 보고되고 있다 (Yoshimatu et al., 1997). 따라서 영양강화를 위한 여러 가지 2차 배양법이 실시되고 있다. 이들 2차 배양은 고도 불포화 지방산 함량이 높은 emulsified oil이 주로 사용되고 있으나, Park et al.(1999)에 의하면 emulsified oil은 rotifer들의 흡착을 유발하여 개체수 감소 등의 문제점을 유발한다고 보고하였다. (중략)

• ALGAE
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• v.31 no.3
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• pp.267-276
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• 2016

Microalgae are currently a very promising source of biomass and triacylglycerol (TAG) for biofuels. In a previous study, we identified Chlorella saccharophila as a suitable source of oil for biodiesel production because it showed high biomass and lipid content with an appropriate fatty acid methyl esters profile. To improve the TAG accumulation in C. saccharophila, in this study we evaluated the effect of abscisic acid (ABA) addition on cell concentration, lipid content and TAG production in this microalga. First, we evaluated the effects of four ABA concentrations (1, 4, 10, and 20 μM) added at the beginning of a single-stage cultivation strategy, and found that all concentrations tested significantly increased cell concentration and TAG content in C. saccharophila. We then evaluated the addition of 1 μM ABA during the second stage of a two-stage cultivation strategy and compared it with a nitrogen deficiency treatment (ND) and a combination of ND and ABA (ND + ABA). Although ABA alone significantly increased lipid and TAG contents compared with the control, ND showed significantly higher TAG content, and ND + ABA showed the highest TAG content. When comparing the results of both strategies, we found a superior response in terms of TAG accumulation with the addition of 1 μM ABA at the beginning of a single-stage cultivation system. This strategy is a simple and effective way to improve the TAG content in C. saccharophila and probably other microalgae as a feedstock for biodiesel production.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.2
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• pp.203-209
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• 2012

We investigated the effect on dietary EPA (eicosapentaenoic acid) source (EP) into formulated diets for growth of brackish flea, Diaphanosoma celebensis. The highest density and specific growth rate (SGR) of brackish fleas were observed on Tetraselmis suecica (TE) trial, but these of trial were not significantly differed with that of Chlorella (CH) + Crypthecodinium sp. (CR) + EP trial, contained EPA oil (P>0.05). Contrastively, CH trial showed the lowest SGR. And in the RNA/DNA ratio, 0.08 of TE trial was the highest ratio out of whole trials, but the trial not significantly differed with that of CH + CR + EP trial (P>0.05). But, the ratio of CH trial was the lowest ratio at 0.05 out of whole trials (P<0.05). Through out results, the EPA source for flea culture was showed a positive effect through their growth and SGR. Therefore, we suggested that a usage of the source with CH could replace T. suecica as good diet for culture of the brackish flea.

• Weed & Turfgrass Science
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• v.5 no.3
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• pp.136-143
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• 2016

This study was conducted to investigate the algicidal characteristics of cashew nut oil (CNO) and to develop CNO mixtures with other compounds having synergistic effects on the growth inhibition against a blue-green alga, Microcystis aeruginosa. Among tested CNOs, CNO with higher anacardic acid contents (Ana-A) exhibited the best algicidal activity against M. aeruginosa. Ana-A showed broad algicidal spectrum with particular greater activity against blue-green algae than green algae. Ana-A showed the greatest activity against to Oscillatoria tenuis ($IC_{50}=0.19{\mu}g\;mL^{-1}$) among the tested blue-green algae and to Chlorella vulgaris ($IC_{50}=4.54{\mu}g\;mL^{-1}$) among the tested green algae, respectively. In a mixture experiment to evaluate a chemical interaction in M. aeruginosa control, Ana-A showed a strong synergistic effect with MSB and menadione, mild synergistic effect with citric acid, and additive effect with chryspophanol, copper sulfate and quinoclamine. Taken together, our results suggest that CNO containing higher anacardic acid can be used as an eco-friendly natural algicide for selective control of blue-green algae such as M. aeruginosa and O. tenuis through an optimization of application rate and in combination with synergists such as MSB and menadione.

• Journal of Korean Society on Water Environment
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• v.32 no.2
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• pp.197-204
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• 2016

The growth of the algae strain Chlorella vulgaris under mixotrophic conditions in the presence of saccharified acorn-starch (acorn-glucose) was evaluated with the objective of increasing biomass growth and triacylglycerols (TAGs) content. The results indicated that 81.3% of starch was converted to glucose in acorns. C.vulgaris algal strains grown with acorn-glucose produced higher biomass and TAGs content than with autotrophic growth. The highest biomass production and TAGs content with 3 g/L acorn-glucose were 12.44 g/L and 32.9%, respectively. Biomass production with 3 g/L acorn-glucose was 16.4 fold higher than under autotrophic growth condition. These findings suggested that 3 g/L acorn-glucose is economic and efficient for biomass production/productivity and TAGs content of microalgae. This study provides a feasible way to reduce the cost of bioenergy production from microalgae.