• Korean Journal of Microbiology
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• v.41 no.4
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• pp.287-292
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• 2005

The cyanobacterial diversity was analyzed by restriction fragment length polymorphism (RFLP) of PCR-amplified rpcBA-Intergenic Spacer (IGS) genes and cpcBA-IGS gene sequencing with a sample collected at Chuso-ri in Daechung Reservoir on March 15, 2005, The Shannon-Weiner diversity index was 0.65, indicating that the cyanobacterial community structure was simple. PCR-RFLP profiles obtained were Phormidium spp. (58 clones), Anabaena spp. (14 clones), Microcystis spp. (4 clones), Spirulina sp. (1 clone) and uncultured cyanobacteria (2 clones). The PCR-RFLP of cpcBA-IGS revealed that Phormidium spp. and Anabaena spp. dominated in the invested sample. As a consequence, it seems that the analysis of functional genes such as cpcBA-IGS can be used for the species identification and community analysis of cyanobacteria.

• Journal of the Korean Society of Food Culture
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• v.36 no.1
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• pp.66-75
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• 2021

Microalgae are unicellular microorganisms inhabiting various ecosystems of the world, including marine and freshwater systems and extreme environments. Only a few species have been actively used as food. Microalgae are attracting attention as a means of biological CO2 reduction because they play an important role in absorbing atmospheric CO2 through their rapid growth by photosynthesis in water. Besides, microalgae are considered to be an eco-friendly energy source because they can rapidly produce biomass containing a large quantum of lipids that can be converted into biodiesel. Several microalgae, such as Chlorella spp., Spirulina spp. and Haematococcus spp. have already been commercialized as functional health supplements because they contain diverse nutrients including proteins, vitamins, minerals, and functional substances such as docosahexaenoic acid (DHA), β-glucan, phycocyanin, astaxanthin, etc. Moreover, they have the potential to be used as food materials that can address the protein-energy malnutrition (PEM) which may occur in the future due to population growth. They can be added to various foods in the form of powder or liquid extract for enhancing the quality characteristics of the foods. In this review, we analyzed several microalgae which can be used as food additives and summarized their characteristics and functions that suggest the possibility of a role for microalgae as future food.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.168-168
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• 2023

The frequent occurrence of cyanobacterial harmful algal blooms (CHABs) in inland waters under climate change seriously damages the ecosystem and human health and is becoming a big problem in South Korea. Satellite remote sensing is suggested for effective monitoring CHABs at a larger scale of water bodies since the traditional method based on sparse in-situ networks is limited in space. However, utilizing a standalone variable of satellite reflectances in common CHABs dual-models, which relies on both chlorophyll-a (Chl-a) and phycocyanin or cyanobacteria cells (Cyano-cell), is not fully beneficial because their seasonal variation is highly impacted by surrounding meteorological and bio-environmental factors. Along with the development of Artificial Intelligence (AI), monitoring CHABs from space with analyzing the effects of environmental factors is accessible. This study aimed to investigate the potential application of AI in the dual-model strategy (Chl-a and Cyano-cell are output parameters) for monitoring seasonal dynamics of CHABs from satellites over Korean inland waters. The Sentinel-3 satellite was selected in this study due to the variety of spectral bands and its unique band (620 nm), which is sensitive to cyanobacteria. Via the AI-based feature selection, we analyzed the relationships between two output parameters and major parameters (satellite water-leaving reflectances at different spectral bands), together with auxiliary (meteorological and bio-environmental) parameters, to select the most important ones. Several AI models were then employed for modelling Chl-a and Cyano-cell concentration from those selected important parameters. Performance evaluation of the AI models and their comparison to traditional semi-analytical models were conducted to demonstrate whether AI models (using water-leaving reflectances and environmental variables) outperform traditional models (using water-leaving reflectances only) and which AI models are superior for monitoring CHABs from Sentinel-3 satellite over a Korean inland water body.

• Journal of Life Science
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• v.26 no.4
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• pp.460-467
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• 2016

A filamentous cyanobacterium, Limnothrix sp. KNUA012, was axenically isolated from a freshwater bloom sample in Lake Hapcheon, Hapcheon-gun, Gyeongsangnam-do, Korea. Its morphological and molecular characteristics led to identification of the isolate as a member of the genus Limnothrix. Maximal growth was attained when the culture was incubated at 25℃. Analysis of its lipid composition revealed that strain KNUA012 could autotrophically synthesize alkanes, such as pentadecane (C₁₅H₃₂) and heptadecane (C₁₇H₃₆), which can be directly used as fuel without requiring a transesterification step. Two genes involved in alkane biosynthesis－an acyl-acyl carrier protein reductase and an aldehyde decarbonylase－were present in this cyanobacterium. Some common algal biodiesel constituents－myristoleic acid (C_14:1), palmitic acid (C_16:0), and palmitoleic acid (C_16:1)－were produced by strain KNUA012 as its major fatty acids. A proximate analysis showed that the volatile matter content was 86.0% and an ultimate analysis indicated that the higher heating value was 19.8 MJ kg⁻¹. The isolate also autotrophically produced 21.4 mg g⁻¹ phycocyanin－a high-value antioxidant compound. Therefore, Limnothrix sp. KNUA012 appears to show promise for application in cost-effective production of microalga-based biofuels and biomass feedstock over crop plants.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.153-161
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• 2020

Arthrospira platensis is the oldest marine microalgae on the planet, is said to contain most of the nutrients needed by the human body. It's components are reported to contain a large amount of various substances such as phycocyanin, chlorophyll and β-carotene, and are known to have an aging and whitening effect. In this study, UVB-induced reactive oxygen species reduction efficacy and antioxidant activity of spirulina purified water extract were investigated. effect was confirmed by measuring DPPH radical scavenging activity, FRAP reducing power and ABTS⁺ radical scavenging activity of 0.05, 0.10, 0.50 1.0 mg/mL of spirulina purified water extract. The coagulation rate, hatching rate and heart rate toxicity were measured by treating spirulina purified water extract with 0.05, 0.10, 0.50 mg/mL concentration using Zebrafish, an alternative experimental animal model. UVB-induced ROS measurement was treated with spirulina extract at 0.05, 0.10, 0.50 mg/mL concentration, and then stained with DCFH-DA to confirm the inhibitory effect of ROS. As a result of measuring antioxidant effect, DPPH, FRAP and ABTS⁺ showed concentration-dependent antioxidant effects in comparison with ascorbic acid. and measuring the coagulation rate, hatching rate, and heart rate using Zebrafish, an alternative experimental animal, it was confirmed that there was no toxicity in 0.05 and 0.10 mg/mL except 0.5 mg/mL compared to the control group. The ROS scavenging activity of UVB-induced zebrafish showed higher ROS reduction than the positive control. The results of this study suggest that spirulina and purified water extracts are valuable for UV and skin protection cosmetics.

• Food Science and Preservation
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• v.18 no.1
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• pp.111-118
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• 2011

The purpose of this study was to develop functional breads added with spirulina, improvement of Quality Characteristics and for long-term storage of spirulina bread. Three different levels of spirulina (0.4, 0.8, 1.2 %) were added to the total amount of ingredient. The weight of spirulina containing bread decreased with spirulina level. During storage, moisture content was higher in spirulina containing breads compared with control bread. During storage, contents of phycocyanin increased with increasing spirulina powder. There was Hunter color value($L^*$, $a^*$ and $b^*$ value) lightness of the crumb of bread with increasing spirulina powder was decreased during storage. Textural properties by TPA showed that hardness was increased during storage, but the hardness of spirulina bread decreased as spirulina addition amount increased. Also, springiness was decreased during storage. The antioxidant activities was decreased with increasing spirulina powder content. Sensory results showed that the scores of over-all preference buy in the bread with spirulina 0.8 % higher than the control and the other groups.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.495-502
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• 2010

Pure lines were isolated from young gametophytic blades of pigmentation and morphological mutants in Porphyra tenera. Growth, blade-shape and photosynthetic pigment content of pure lines were compared with the wild type. Growth of blade length in the wild type (W, R-B), with round shape and brown color, was fastest at $5{\sim}10^{\circ}C$ and became slower as temperature increased. The blade-shape of the wild type changed from linear to round as temperature increased. The green type (R-G), with round shape and green color, showed slower growth, and the red type (R-R) 'with round shape and red color' showed faster growth than the wild type. The blade-shapes of the green and red types changed from elliptical or linear to round as temperature increased. The phycoerythrin (PE) / phycocyanin (PC) ratio of the green type was markedly lower and the PE/PC ratio of the red type was markedly higher than that of the wild type. The linear type (L-B), with liner shape and brown color, showed faster growth in blade length than the wild type at $10{\sim}20^{\circ}C$ and maintained its linear shape at $5{\sim}15^{\circ}C$. The content of photosynthetic pigments of the linear type was similar to that of the wild type. Each of the pure lines of pigmentation and morphological mutants that were isolated in the present study showed particular patterns in growth, blade-shape and photosynthetic pigment composition. Therefore, they are expected to be useful as new varieties by themselves and to be available for breeding and biotechnological studies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.131-140
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• 2015

To set up unicellular cyanobacterial strains with photo-biological $H_2$ production potential, live samples were repeatedly collected from 68 stations in the coastal zone of Korea for the four years since 2005. Among 77 cyanobacterial strains established six (KNU strains, CB-MAL002, 026, 031, 054, 055 and 058) were finally chosen as the excellent strains for $H_2$ production with $H_2$ accumulation over 0.15 mL $H_2\;mL^{-1}$ under general basic $H_2$ production conditions as well as positive $H_2$ production for more than 60 hr. To explore optimum procedures for higher $H_2$ production efficiency of the six cyanobacterial strains, the inter-strain differences in the growth rate under the gradients of water temperature and salinity were investigated. The maximum daily growth rates of the six strains ranged from 1.78 to 2.08, and all of them exhibited $N_2-fixation$ ability. Based on the similarity of the 16S rRNA sequences, all the test strains were quite close to Cyanothece sp. ATCC51142 (99%). The six strains, however, were grouped into separate clades from strain ATCC51142 in the molecular phylogeny diagram. Chlorophyll- a content was 3.4~7.8% of the total dried weight, and the phycoerythrin and phycocyanin contents were half of those in the Atlantic strain, Synechococcus sp. Miami BG03511. The growth of the six strains was significantly suppressed at temperatures above the optimal range, $30{\sim}35^{\circ}C$, to be nearly stopped at $40^{\circ}C$. The growth was not inhibited by high salinities of 30 psu salinity in all the strains while strain CB055 maintained its high growth rate at low salinities down to 15 psu. The euryhaline strains like CB055 might support massive biotechnological cultivation systems using natural basal seawater in temperate latitudes. base seawater. The biological and ecophysiological characteristics of the test strains may contribute to designing the optimal procedures for photo-biological $H_2$ production by unicellular cyanobacteria.

• Journal of the Korean Applied Science and Technology
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• v.35 no.2
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• pp.423-432
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• 2018

Arthrospira platensis is one of the oldest algae in the world and has been reported to have anti-aging properties, including phycocyanin, tocopherol and beta-carotene. In this study, we tried to search protective activities against UVB-induced reactive oxygen species(ROS) of Arthrospira platensis under indoor cultivation ethanol extracts(ICAE) and outdoor cultivation ethanol extracts(OCAE). The anti-oxidative capacities were evaluated by DPPH radical scavenging activity and SOD-like activities at various concentrations(0.1, 0.5, $1mg/m{\ell}$) of ICAE and OCAE. Zebrafish embryos and HaCaT cells were exposed to UVB radiation and treated with various concentrations(0, 0.01, 0.05, 0.1, 0.5, $1mg/m{\ell}$) of ICAE and OCAE. ROS levels of zebrafish and HaCaT cells were generated by UVB radiation. ROS levels were detected using a fluorescent microscope after DCFH-DA staining. The DPPH radical scavenging activity of ascorbic acid was 73% and SOD-like activity was 86% in the positive control group. ICAE and OCAE at $1mg/m{\ell}$ concentration showed 43, 57% DPPH radical scavenging activity and 20, 19% SOD-like activity. Anti-oxidative of ICAE and OCAE had lower effects than the positive control ascorbic acid but significant results. ROS of UVB-induced zebrafish embryos and HaCaT cells were higher than negative control. ICAE and OCAE treated group decreased ROS concentration dependently than UVB-induced positive control group. These results suggest that Arthrospira platensis ethanol extract may have usability value as a cosmetic material for skin protection.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.280-288
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• 1990

Quality stability of dried lavers during roasting and storage was investigated by measuring the changes of pigment contents including chlorophyll a, carotenoids and biliproteins, the content of trypsin indigestible substrates(TIS), in vitro apparent protein digestibility, and dietary fiber. In heat treatment or roasting of dried laver, carotenoids and chlorophyll a were found to be more stable than biliproteins. Chlorophyll a and carotenoids were retained more than $85\%$ during roasting for 1 hour at $120^{\circ}C$ while biliproteins were retained only $10\%$ at the same temperature. The in vitro digestility of dried layers tended to increase with raising the roasting temperature. The in vitro digestibility of $85\%$ for the roasted laver at $100^{\circ}C$ was higher than that observed in the control of $80\%$. There was a correlation between the decrease in TIS and biliproteins as the laver was roasted. The soulble dietary fiber(SDF) content was substantially increased by heat treatment. The extent of protein digestiblility appeared to be related to the increase of SDF content. In the storage of roasted lavers under both water activities 0.1 and 0.65, the loss of the pigments and TlS were markedly retarded at Aw 0.1. Chlorophyll a was retained about $20\%$ at aw 0.65 and $75\%$ at aw 0.1 after 20 week sto-rage. At worst, more than $90\%$ of the carotenoids were lost at aw 0.65 after 20 week, while biliproteins were comparatively stable at the same water activity. TIS decreased about $15\%$ and in vitro apparent protein digestibility increased up to $92\%$ at aw 0.65 during storage.