• Journal of Korean Society on Water Environment
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• v.31 no.2
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• pp.134-141
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• 2015

The focus of this study was to observe the growth of Chlorella vulgaris and Botryococcus braunii under mixotrophic conditions (i.e., added acorn) with the aim of increasing biomass and triacylglycerols (TAGs) content. The result of investigation indicated that the acorn contains a lot of carbonate (87.29%) and glucose (97.99 mg%). A significant growth of biomass was obtained when grown in acorn rich environment comparing to autotrophic conditions. 3 g/L acorn yielded the highest biomass concentration for these strains. Thus, the biomass productivity with 3 g/L acorn was obtained 2.31 times and 2.10 times higher than that of authotrophic conditions for Chlorella vulgaris and Botryococcus braunii, respectively. The maximum amount of TAGs was reached 14.35% and 18.41% for Chlorella vulgaris and Botryococcus braunii, respectively, in the growth medium with 5 g/L acorn. The effect of acorn could enhance the investigated microalgae growth, biomass productivity and TAGs content. This provides a feasible way to reduce the cost of bioenergy production from microalgae.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.373-383
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• 2018

Fouling by solids and microorganisms is the major obstacle limiting the efficient use of membrane wastewater treatment. In our previous study, two stages microalgae/membrane filtration system was proposed to treat anaerobic digested palm oil mill effluent (AnPOME). This two stages microalgae/membrane filtration system had showed great potential for the treatment of AnPOME with high removal of COD, $NH_3-N$, $PO_4{^{3-}}$, TSS, turbidity, and colour. However, fouling behavior of the membrane in this two stages microalgae/membrane filtration system was still unknown. In this study, empirical models that describe permeate flux decline for dead-end filtration (pore blocking - complete, intermediate, and standard; and cake layer formation) presented by Hermia were used to fit the experimental results in identifying the fouling mechanism under different experimental conditions. Both centrifuged and non-centrifuged samples were taken from the medium with 3 days RT intervals, from day 0 to day 12 to study their influence on fouling mechanisms described by Hermia for ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) filtration mode. Besides, a more detailed study on the use of resistance-in-series model for deadend filtration was done to investigate the fouling mechanisms involved in membrane filtration of AnPOME collected after microalgae treatment. The results showed that fouling of UF and NF membrane was mainly caused by cake layer formation and it was also supported by the analysis for resistance-in-series model. Whereas, fouling of RO membrane was dominated by concentration polarization.

• Journal of Marine Bioscience and Biotechnology
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• v.11 no.2
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• pp.81-88
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• 2019

In this study, effects of nitrogen (N) and phosphorus (P) starvation on the cell growth and fatty acid (FA) production of newly isolated freshwater microalgae were investigated. The microalgae were identified as Chlorella sp. and Parachlorella sp. through 18S rRNA sequencing. Optimal culture temperature and light intensity were investigated using a high-throughput photobioreator, and the result was validated in 0.5 L bubble column photobioreactors using BG-11 without NaNO₃ and/or K₂HPO₄. Under nutrient starvation conditions, total FA contents of the microalgae were significantly changed rather than FA composition. Starvation of both N and P was most effective for increasing FA contents in Parachlorella sp (24.4±0.1%) whereas highest FA contents (42.6±1.8%) was achieved when only P was starved in Chlorella sp. among tested conditions. These results suggest an effective strategy for increasing FA production from microalgae using appropriate nutrient starvation.

• Microbiology and Biotechnology Letters
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• v.46 no.3
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• pp.225-233
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• 2018

In this exploratory study, eight types of microalgae from different phyla (Chlamydomonas reinhardtii, Chlorella species, Haematococcus pluvialis, Porphyridium purpureum, Porphyridium cruentum, Isochrysis species, Isochrysis galbana, and Pavlova lutheri) were tested for their antibacterial activities against eight target pathogenic bacterial strains. The agar well diffusion method and broth micro dilution assay were conducted to estimate the antibacterial activity. Microalgae cell-free supernatants, exopolysaccharides (EPS), water, and organic solvent extracts were used for inhibition analysis. EPS extracted from P. lutheri showed activity against Bacillus subtilis and Pseudomonas aeruginosa. Inhibition zone diameters of 14-20 mm were recorded on agar plates, while the minimum inhibitory concentrations in the broth micro dilution assay were $0.39-25mg\;ml^{-1}$. During this study, haptophyte microalgae, Isochrysis species, and P. lutheri extracts showed the highest activity against most of the tested pathogenic bacterial strains, while most of the extracts were active against the important foodborne pathogen P. aeruginosa. This study showed promising results regarding important microalgae phyla, which will further aid research related to extracts and exploitation of bioactive metabolic compounds in the food and pharmaceutical industries.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.643-649
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• 2015

Although microalgae are considered as a promising feedstock for biofuels, cost-efficient harvesting of microalgae needs to be significantly improved. In this study, the use of electro coagulation as a more rapid flocculation method for harvesting a freshwater (Scenedesmus dimorphus) microalgae species was evaluated. The results showed that, electro coagulation was shown to be more efficient using an aluminum anode than using an iron anode. And optimum conditions of electro coagulation for harvesting Scenedesmus dimorphus were found. The optimum stirring speed was 100 rpm and optimum pH was 5. Furthermore, the current density which the fastest and highest recovery efficiency is achieved at $30A/m^2$, while the highest energy efficiency was achieved at $10A/m^2$. A the rapid and high recovery efficiency indicate that electro coagulation is a particularly attractive technology for harvesting microalgae.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.8-16
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• 2014

Microalgae have been considered as a promising microorganism in the field of bio-industry due to their abilities to fix carbon dioxide as well as biosynthesize valuable secondary metabolites. Of many lighting sources for microalgal cultivation, LED (Lighting Emitting Diode) has been emerged as the appropriate choice with multiple advantages over the conventional bulbs. However, it is only in recent years that we have witnessed the possibility of application of LED into microalgae cultivation system. LED will serve as an evolutionary lighting source for microalgae cultivation system and open the frontier for integrative bio-industries. In this paper, we present the comprehensive review on the recent trends of LED applications into microalgal biotechnology.

• Journal of Korean Society on Water Environment
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• v.39 no.2
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• pp.181-193
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• 2023

Distribution changes in microalgae communities were studied in the Nakdonggang River at two sampling stations (St.1 Gyeongcheongyo Bridge (GB) and St.2 Daedong Wharf (DW)) at monthly intervals from January 2021 to November 2021. A total of 83 taxa included 82 species, 1 forma, belonging to 49 genera, 32 families, 21 orders, and 8 classes. The most important groups were Bacillariophyta and Chlorophyta. The number of species ranged from 5 to 24 in GB, and from 9 to 21 taxa in DW. The contribution of Bacillariophyta to the total species richness was the highest during all survey periods, and Chlorophyta yielded the next highest value in the study area. The dominant taxa were Aulacoseira ambigua, A. ambigua f. japonica, and Ulnaria acus in this study. Cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on Bray- Curtis similarity identified 4 major groups, which corresponded to microalgae assemblages and their characteristic species. Correlation was analyzed through the CCA analysis. It was found that there was a correlation between the microalgae and environmental factors. It was revealed that the divided groups were distinguished because of the differences by the survey period. Therefore, seasonal change was judged as a major factor affecting the distribution of microalgae communities.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.7
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• pp.973-978
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• 2017

Objective: The aim of this study was to investigate the effects of simultaneous supplementation of laying hens with alpha-linolenic acid (ALA) resources (flax, perilla, and Eucommia ulmoides [E. ulmoides] seeds) and eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) resources (Schizochytrium sp.) on egg quality and n-3 polyunsaturated fatty acids (PUFA) profile. Methods: Dietary treatments were as follows: i) diet C (control diet); ii) diet F (diet C+10% flaxseeds); iii) diet P, (diet C+10% perilla seeds); iv) diet E (diet C+10% E. ulmoides seeds); v) diet A (diet C+1.5% microalage); vi) diet AF (diet C+10% flaxseeds+1.5% microalage); vii) diet AP (diet C+10% perilla seeds+1.5% microalgae); viii) diet AE (diet C+10% E. ulmoides seeds+ 1.5% microalage). Results: Egg weight, yolk weight and production ratio were not significantly affected by either algae or in combination with seeds (p>0.05). No significant difference was observed in ALA and DHA concentration in eggs between flaxseed, perila, and E. ulmodies seeds supplementation alone (p>0.05). N-3 PUFA in eggs was slightly improved by microalgae supplementation. The best supplementation, a combination of microalgae and perilla seeds, elevated (p<0.05) ALA from 19.7 to 202.5 mg/egg and EPA+DHA from 27.5 to 159.7 mg/egg. Highest n-3 PUFA enrichment (379.6 mg/yolk) was observed with supplementation of a combination of perilla seed and microalgae (362.2 mg/yolk), followed by a combination of flaxseed and microalgae (348.4 mg/yolk). The ALA, EPA, and DHA content obtained with a combination of microalgae and seeds surpassed the total sum of that obtained with microalgae or ALA-seeds alone. Conclusion: It is feasible to enrich eggs with n-3 PUFAs by perilla or E. ulmodies seeds instead of flaxseeds. Simultaneous supplementation of microalgae and seeds helped improve the transfer from EPA and docosapentaenoic acid into DHA.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.937-938
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.945-946
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• 2012