• ALGAE
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• 제35권3호
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• pp.253-262
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• 2020

Haematococcus pluvialis is a commercial microalga that can produce high quantities of astaxanthin. Under induced conditions, some important changes in the subcellular structures related to astaxanthin accumulation were observable. For example, a large number of astaxanthin granules, oil structures and starch granules appeared in the thick-walled cells; Astaxanthin granules gradually dissolved into the oil structures and spread throughout the entire cell with the fusion and diffusion process of oil structures during the middle and late stages of induction; The plastoglobules were closed to the newly formed structures, and some plastoglobules would abnormally increase in size under stress. Based on observations of cell damage, the degradation of membrane structures, such as chloroplasts, was found to be the primary form of damage during the early stage of induction. During the middle stage of induction, some transparent holes were exposed in the dissolving astaxanthin granules in the cytoplasm. In thick-walled cells, these transparent holes were covered by oil substances dissolving astaxanthin, thereby avoiding further damage to cells. Given the relatively few oil structures, in non-thick-walled cells, the transparent holes expanded to form multiple transparent areas, eventually resulting in the rupture and death of cells. These results suggested that the high level of synthesis and the wide range diffusion of oil explained the expansion of astaxanthin in H. pluvialis.

• 한국미생물·생명공학회지
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• 제34권2호
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• pp.136-142
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• 2006

Haematococcus pluvialis는 astaxanthin을 많이 생산하는 미세조류로써 astaxanthin은 항산화제로 면역반응을 강화시켜주며 항암효과 등을 가지고 있다. 그런데 야생종의 낮은 생장속도와 astaxanthin의 생산에는 한계가 있기 때문에 이를 극복하기위해 돌연변이 방법을 사용하였다. 돌연변이 방법으로는 자외선 조사와 EMS와 colchicines 처리를 사용하여 야생종보다 colony가 크고 더 붉은 것은 선택하였다. 선별된 돌연변이들은 carotenoid 생합성과정을 억제하는 nicotine 과 diphenylamine을 이용하여 다시 선별하였다. 그때 생존율은 40-50%이었고 여기서 선별된 균주들을 다시 규모를 키워 배양한 결과 자외선 처리한 돌연변이인 U15-5가 야생종보다 세포당 total carotenold 생산량이 1.68배 증가하였고, colchicine 처리한 DS와 M4-3은 생장속도가 $20\sim30%$ 증가하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.298-300
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• 2001

본 실험의 결과, H. pluvialis의 배양에 있어서 고농도의 $CO_2$를 공급함으로서 세포의 성장속도가 의미 있게 증가함을 알았고, 더불어 $CO_2$가 공급되는 경우, acatate 와 같은 유기탄소원이 오히려 세포의 성장을 저해함을 알 수 있었다.

• KSBB Journal
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• 제24권6호
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• pp.570-578
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• 2009

헤마토코커스로부터 아스타잔틴의 추출과 제형화의 유효성을 확인하고 적용성을 검토하고자 헤마토코커스 추출물과 아스타잔틴 포접화합물의 생리활성을 측정하였다. 그 결과, 헤마토코커스 추출물은 DPPH 라디칼 소거능, xanthine oxidase 저해 활성 및 hydroxyl 라디칼 소거능에 대해 in vitro 실험에서 활성을 나타냈다. 또한 헤마토코커스 추출물은 대조군인 kojic acid에 비해 동일한 농도에서 2배 이상의 미백활성을 나타냈고, 자궁암 세포주 (HeLa)에 대해 대조항암물질인 5-fluorouracil (5-FU)과 비슷한 항암활성을 나타냈다. 아스타잔틴은 또한 숙취해소 효과를 갖고 있는 것으로 확인되었는데, 대조군인 지구자 추출물에 비해 1.5배 높음을 알 수 있었다. 또한, 아스타잔틴과 싸이클로덱스트린의 포접화합물 As-$\beta$-CD와 헤마토코커스 추출물과 싸이클로 덱스트린의 포접화합물인 H.p.-$\beta$-CD의 생리활성을 조사한 결과, As-$\beta$-CD는 대조군인 지구자추출물보다 높은 숙취해소 효과를 나타냈고, H.p.-$\beta$-CD는 대조군인 kojic acid와 비슷한 수준의 미백효과를 나타냈다.

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.1922-1929
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• 2007

A simple whole-cell-based sensing system is proposed for determining the cell mass of H. pluvialis using ultraviolet fluorescence spectroscopy. An emission signal at 368 nm was used to detect the various kinds of green, green-brown, brown-red, and red H. pluvialis cells. The fluorescence emission intensities of the cells were highest at 368 nm with an excitation wavelength of 227 nm. An excitation wavelength of 227 nm was then selected for cell-mass sensing, as the emission fluorescence intensities of the cell suspensions were highest at this wavelength after subtracting the background interference. The emission fluorescence intensities of HPLC-grade water, filtered water, and HPLC-grade water containing a modified Bold's basal medium (MBBM) were measured and the difference was less than 1.6 for the selected wavelengths. Moreover, there was no difference in the emission intensity at 368 nm among suspensions of the various morphological states of the cells. A calibration curve of the fluorescence emission intensities. and cell mass was obtained with a high correlation ($R^2=0.9938$) for the various morphological forms of H. pluvialis. Accordingly, the proposed method showed no significant dependency on the various morphological cell forms, making it applicable for cell-mass measurement. A high correlation was found between the fluorescence emission intensities and the dry cell weight with a mixture of green, green-brown, brown-red, and red cells. In conclusion, the proposed model can be directly used for cell-mass sensing without any pretreatment and has potential use as a noninvasive method for the online determination of algal biomass.

• Journal of Microbiology and Biotechnology
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• 제25권5호
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• pp.637-647
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• 2015

In this study, we attempted to understand signaling pathways behind lipid biosynthesis by employing a chemical genetics approach based on small molecule inhibitors. Specific signaling inhibitors of MAP kinase or modulators of cAMP signaling were selected to evaluate the functional roles of each of the key signaling pathways in three different microalgal species: Chlamydomonas reinhardtii, Chlorella vulgaris, and Haematococcus pluvialis. Our results clearly indicate that cAMP signaling pathways are indeed positively associated with microalgal lipid biosynthesis. In contrast, MAP kinase pathways in three microalgal species are all negatively implicated in both lipid and carotenoid biosynthesis.

• 한국미생물·생명공학회지
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• 제46권3호
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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 Microbiology and Biotechnology
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• 제15권4호
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• pp.880-886
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• 2005

Using carotenoid genes of Erwinia herbicola, metabolic engineering was carried out for lycopene production with the pAC-LYCO4 plasmid, which was composed of a chromosomal DNA fragment of E. herbicola containing the crtE, crtB, and crtI genes under the control of the tetracycline promoter and the ipi gene of Haematococcus pluvialis with the trc promoter. Plasmid pAC-LYCm4 was constructed for efficient expression of the four exogenous genes using a strong RBS sequence and the same tetracycline promoter. The optimized expression construct of pAC-LYCm4 increased Iycopene production three times as compared with pAC-LYCO4. pAC-LYCm5 containing ispA behind the four exogenous genes was constructed. There was no significant difference in Iycopene production and cell growth between pAC-LYCm4 and pAC-LYCm5. FPP synthase encoded by ispA was not rate-limiting for Iycopene production. Each gene of crtE, crtB, crtI, and ipi was overexpressed, using pBAD-crtE, pBAD-crtIB, and pBAD-ipiHPI, in addition to their expression from pAC-LYCm4. However, there was no increase oflycopene production with the additional overexpression of each exogenous gene. The four exogenous genes appeared to be not rate-limiting in cells harboring pAC-LYCm4. When pDdxs, pBAD24 containing dxs, was introduced into cells harboring lycopene synthetic plasmids, lycopene production of pAC-LYCO4, pAC-LYCm4, and pAC-LYCm5 was increased by 4.7-, 2.2-, and 2.2-fold, respectively. Lycopene production of pBAD-DXm4 containing crtE, crtB, crtI, ipi, and dxs was 5.2 mg/g dry cell weight with $0.2\%$ arabinose, which was 8.7-fold higher than that of the initial strain with pAC-LYC04. Therefore, the present study showed that proper regulation of a metabolically engineered pathway is important for Iycopene production.