• ALGAE
• /
• v.24 no.2
• /
• pp.121-127
• /
• 2009

The unicellular green alga, Haematococcus pluvialis, accumulates the highest level of astaxanthin among knownastaxanthi.n-producing organisms. Light is the most important factor to induce astaxanthin by H. pluvialis. BIue andred LEDs, whose ${\lambda}_{max}$'s are 470 and 665 nm, respectively, were used for internally illuminated light sources.Fluorescent lamps were also used for both internal and external illumination sources. The astaxanthin levels in thesevarious lighting systems were analyzed and compared each other. The cultures under internally illuminated LEDsaccumulaled 20% more astaxanthin than those under fluorescent lamp. Furthermore, LEDs generated much lessheat than the fluorescent lamps, which gives one more reason for the LEDs being a suitable internal Light source forastaxanthin induction. The results reported here would lead novel designs of photobioreactors with improvementsof illumination methods for high level of astaxanthm production. The maximum astaxanthin concentrations as wellas the astaxanthin yield per supplied photon were increased by at least 20% when blue or red LEDs were supplied.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.478-481
• /
• 2006

Energy is vital to global prosperity, yet dependence on fossil fuels as our primary energy source contributes to global climate change environmental degradation, and health problems. Hydrogen $(H_2)$ offers tremendous potential as a clean renewable energy currency. Hydrogen has the highest gravimetric energy density of any known fuel and is compatible with electrochemical and combustion processes for energy conversion without producing carbon-based emission that contribute to environmental pollution and climate change. Numerous methodologies have been developed for effective hydrogen production. Among them, the biological hydrogen production has gained attention, because hydrogen can be produced by cellular metabolismunder the presence of water and sunlight. The green alga Chlamydomonas reinhardtii is capable of sustained $H_2$ photoproduction when grown under sulfur deprived condition. Under sulfur deprived conditions, PSII and photosynthetic $O_2$ evolution are inactivated, resulting in shift from aerobic to anaerobic condition in the culture. After anaerobiosis, sulfur deprived algal cells induce a reversible hydrogenase and start to evolve $H_2$ gas in the light. According to above principle, we investigated the effect of induction parameters such as cell age, cell density. light intensity, and sulfate concentration under sulfur deprived condition We also developed continuous hydrogen production system by sulfate re-addition under sulfur deprived condition.

• Journal of Aquaculture
• /
• v.13 no.3
• /
• pp.253-258
• /
• 2000

Monthly samplings were made at Yongho-dong, Pusan, on the south eastern coast of Korea from May 1998 to April 1999 to investigate population growth and regeneration pattern of C. okanurae. The growth of erect branches was dependent mainly on the habitat water temperature. Maximum length of an erect branch was 13.4 cm in July and the minimum was 5.1 cm in March; during the corresponding months maximum and minimum weights of the alga were 2.2 and 0.7 g, respectively. During this investigation, gametangia did not occur. Regeneration of excised ramuli was dependent on irradiance. Regeneration rate was the highest under 50 ${\mu}$molm$^{-2}$s$^{-1}$ at 2$0^{\circ}C$. Under the conditions of different combinations of temperature (18, 22, 25, 28 and 1$^{\circ}C$) and irradiance (10, 20, 40, 60 and 100 ${\mu}$molm$^{-2}s$ $^{-1}$) regimes, regeneration of excised erect branch was highly affected by temperature and irradiance. The highest regeneration occurred at 25 $^{\circ}C$ and 20 ${\mu}$molm$^{-2}s$$^{-1}$, whereas the highest growth in length (4.5${\pm}$1.0 cm) and fresh weight (1.2${\pm}$0.7 g) was attained after 15 days of culture.

• The Korean Journal of Pesticide Science
• /
• v.8 no.2
• /
• pp.117-128
• /
• 2004

The influence of different feeding rates of three green algae on growth and reproduction in four Korean cladocera, Daphnia sp., Daphnia obtusa, Moina macrocopa, and Simocephalus vetulus was investigated. The growth and reproduction rates of Daphnia sp. fed Chlorella vulgaris cells were significantly increased than those of daphnid fed Senedesmus subspicatus and Selenastrum carpricornutum. The total offsprings of Daphnia sp. fed $25\times10^4$ and $50\times10^4$ cells Chlorella vulgaris for 21days were $124{\pm}2.8$ and $168{\pm}22.1$, respectively. The Daphnia obtusa fed $25\times10^4$ and $50\times10^4$ cells Selenastrum carpricornutum was shown good reproduction rates, $72.2{\pm}7.9$ and $79.6{\pm}22.9$, respectively. The Moina macrocopa fed $25\times10^4$ and $50\times10^4$ cells Senedesmus subspicatus as well as Simocephalus vetulus and $25\times10^4$ and $50\times10^4$ cells Chlorella vulgaris were shown good reproduction rates. All of algae tested were sufficient as a good diet for Korean Cladocerans in this study. However, the preferred alga was Chlorella vulgaris and the optimal feeding concentrations were $2.5\times10^5\sim5\times10^5$ cells/mL, because the alga was shown most stable and generally high production rates in all cladocerans tested.

• Korean Journal of Environmental Biology
• /
• v.17 no.1
• /
• pp.1-9
• /
• 1999

Numerous observations revealed strong evidence of increased middle ultraviolet radiation or UV-B (280 ~ 320 nm) at the earth's surface resulting from stratospheric ozone depletion. UV is the waveband of electromagnetic radiation which is strongly absorbed by nucleic acids and proteins, thus causing damage to living systems. It has been recorded in the East Sea, Korea that solar UV-B impinging on the ocean surface penetrates seawater to significant depths. Recent researches showed that exposure to UV-B for as short as 2h at the ambient level (2.0 Wm$^{-2}$) decreased macroalgal growth and photosynthesis and destroyed photosynthetic pigments. These may suggest that UV-B could be an important environmental factor to determine algal survival and distribution. Some adaptive mechanisms to protect macroalgae from UV-damage have been found, which include photoreactivation and formation of UV-absorbing pigments. Post-illumination of visible light mitigated UV-induced damage in laminarian young sporophytes with blue the most effective waveband. The existence of UV-B absorbing pigments has been recognized in the green alga, Ulva pertusa and the red alga, Pachymeniopsis sp., which is likely to exert protective function for photosynthetic pigments inside the thalli from UV-damage. Further studies are however needed to confirm that these mechanisms are of general occurrence in seaweeds. Macroalgae together with phytoplankton are the primary producers to incorporate about 100 Gt of carbons per year, and provide half of the total biomass on the earth. UV-driven reduction in macroalgal biomass, if any, would therefore cause deleterious effects on marine ecosystem. The ultimate impacts of increasing UV-B flux due to ozone destruction are still unknown, but the impression from UV studies made so far seems to highlight the importance of setting up long-term monitoring system for us to be able to predict and detect the onset of large -scale deterioration in aquatic ecosystem.

• The Korean Journal of Pesticide Science
• /
• v.12 no.3
• /
• pp.222-228
• /
• 2008

Algal Growth-inhibition tests were conducted with 6 pesticides butachlor GR (5%), butachlor EW (33%), isoprothiolane GR (12%), isoprothiolane EC (40%), diazinon GR (3%) and diazinon EC (34%) to determine their comparative toxicity to three species of freshwater green algae Selenastrum capricornutum, Scenedesmus subspicatus, Chlorella vulgris and one species diatom Nitzschia palea. The test species were exposed to the test pesticide for 72 hours and the toxicity represented $EC_{50}$ value calculated by the reduction in growth rate at 72 hours. The toxicity of EC or EW formulation to green algae and diatom was higher than the toxicity of GR formulation at all test in this study. Also, the toxicity of EC formulation was higher than the toxicity technical pesticide. These results indicate that the types of pesticide formulation may affect on their toxicity on algae and the green alga, S. capricornutum and S. subspicatus were more sensitive than C. vulgris. Also, the sensitivity of the diatom, N. palea showed equal or lower than S. capricornutum, S. subspicatus but more sensitive than C. vulgris.

• KSBB Journal
• /
• v.25 no.4
• /
• pp.357-362
• /
• 2010

Green alga, Ulva pertusa kjelmann has been known to be one of the largest pollutants in Korea. Therefore, the efficient pretreatment processes have been required to improve the yields of fermentable sugar. The optimal pretreatment conditions were determined to be $195^{\circ}C$ for 15 min. The sugar yield of glucose and xylose were estimated as 20.5%, and 5.0% respectively, based on theoretical yields. However solid residues were estimated enzymatic digestibility of 90-95% with cellulase loading of 15 FPU/g glucan. This process was proved to generate the low concentration of Hydroxy-Methyl-Furfural (51 ppm), which resulted in ethanol production with 95% of the maximum conversion yield from glucose in the culture of Saccharomyces cerevisiae (ATCC, 24858). This study showed that Ulva pertusa kjellmann can be used as a bioetahnol resource using the high temperature liquefaction process.

• Korean Journal of Pharmacognosy
• /
• v.41 no.1
• /
• pp.43-47
• /
• 2010

In order to screen new receptor tyrosine kinase inhibitor which is expected to be anticancer drug lead, we have investigated receptor tyrosine kinase inhibitory activity on the marine alga-derived symbiotic microorganisms (500 strains). The significant activities (over 70% inhibition at $10\;{\mu}g/ml$) were observed in the extracts of ten strains (Strain No.: MFA018, 019, 206, 242, 325, 335, 343, 344, 354, 356), isolated from marine red algae, five strains (Strain No.: MFA030, 126, 213, 324, 339), isolated from the brown algae, and one strain (Strain No.: MFA272), isolated from the marine green algae, respectively. Among the active strains, MFA019 and 356 showed strong receptor tyrosine kinase inhibitory activity with $IC_{50}$ values of 0.6 and $0.9\;{\mu}g/ml$, respectively.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.2
• /
• pp.71-76
• /
• 2000

The biological carbon dioxide fixation using microalgae has been known as an effective carbon dioxide reduction technology. With many environmental factors influencing microalgal productivity, the desirable cultivation factors were investigated using a green alga, Euglena gracilis. It has the high protein and vitamin E to be used as fodder. In batch culture with a photobioreactor, initial pH, temperature, carbon dioxide concentration and light intensity in the optimum cultivation condition were 3.5, $27^{\circ}C$,5-10% and $520{\mu}mol/m^2/s$, respectively. After that, the optimum hydraulic retention time (HRT for the continuous cultivation was 4 days at carbon dioxide concentration of 10%. In this condition, the final dry cell weight was 1.2g/l.

• Journal of Microbiology and Biotechnology
• /
• v.11 no.2
• /
• pp.211-216
• /
• 2001

The growth of Selenastrum capricornutum in culture was investigated as a function of ionic copper concentrations to verify the toxicity and physiological variation. In a $Cu^{++}$ excess culture (E: $Cu^{++}$ of $130{\mu}g/l$), the growth rate (K)(0.32) was lower than that of the control culture (C: $Cu^{++}$ of $0.065{\mu}g/l$) (0.61) after 8 days and the exponential growth rate ($R_E$) was also found to be lower in culture E (1.1) than culture C (2.9). On the contrary, the K of S. capricornutum in trace $Cu^{++}$ culture ($T_1$ and $T_2$, 0.72) after 6 days tended to be more increased than culture C (0.68). From 8 to 14 days of culture, the amounts of chlorophyllls a and b were increased in culture C (chlorophyll a, $106->126{\mu}g/g$ dry wt; chlorophyll b, $158->208{\mu}g/g$ dry wt; chlorophyll b were decreased in culture E (chlorophyll a, $309->235{\mu}g/g$ dry wt; chlorophyll b, $405->352{\mu}g/g$ dry wt). The amounts of chlorophylls in ionic copper trace culture ($T_1$ and $T_2$) [(chl a/b) of $T_1$: $384/620\;{\mu}g/g$ dry wt; (chl a/b) of $T^2$:$320/467{\mu}g/g$ dry wt] were increased more than the culture C($260/387{\mu}g/g$ dry wt). Howeveer, when photosynthetic rates were normalized to the dry weight of algae, the control culture continued to showed higher values than the treated culture ($T_1$). An appropriate amount of ionic copper ($T_1:\;26\;{\mu}g/l$) stimulated the grwoth of S. capricornutum than the ionic copper content of $13\;{\mu}g/l$ ($T_2$), while the excess amount of ionic copper ($130\;{\mu}g/l$) resulted in the highest toxicity to the growth of S. capricornutum.