• ALGAE
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• 제28권2호
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• pp.131-147
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• 2013

Major progress has been made in the past decade towards understanding of the biosynthesis of red carotenoid astaxanthin and its roles in stress response while exploiting microalgae-based astaxanthin as a potent antioxidant for human health and as a coloring agent for aquaculture applications. In this review, astaxanthin-producing green microalgae are briefly summarized with Haematococcus pluvialis and Chlorella zofingiensis recognized to be the most popular astaxanthin-producers. Two distinct pathways for astaxanthin synthesis along with associated cellular, physiological, and biochemical changes are elucidated using H. pluvialis and C. zofingiensis as the model systems. Interactions between astaxanthin biosynthesis and photosynthesis, fatty acid biosynthesis and enzymatic defense systems are described in the context of multiple lines of defense mechanisms working in concert against photooxidative stress. Major pros and cons of mass cultivation of H. pluvialis and C. zofingiensis in phototrophic, heterotrophic, and mixotrophic culture modes are analyzed. Recent progress in genetic engineering of plants and microalgae for astaxanthin production is presented. Future advancement in microalgal astaxanthin research will depend largely on genome sequencing of H. pluvialis and C. zofingiensis and genetic toolbox development. Continuous effort along the heterotrophic-phototrophic culture mode could lead to major expansion of the microalgal astaxanthin industry.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권6호
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• pp.322-330
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• 2003

The unicellular green alga Haematococcus pluvialis has recently attracted great inter-est due to its large amounts of ketocarotenoid astaxanthin, 3,3'-dihydroxy-${\beta}$,${\beta}$-carotene-4,4'-dione, widely used commercially as a source of pigment for aquaculture. In the life cycle of H. pluvialis, astaxanthin biosynthesis is associated with a remarkable morphological change from green motile vegetative cells into red immotile cyst cells as the resting stage. In recent years we have studied this morphological process from two aspects: defining conditions governing astaxanthin biosynthesis and questioning the possible function of astaxanthin in protecting algal cells against environmental stress. Astaxanthin accumulation in cysts was induced by a variety of environmental conditions of oxidative stress caused by reactive oxygen species, intense light, drought, high salinity, and high temperature. In the adaptation to stress, abscisic acid induced by reactive oxygen species, would function as a hormone in algal morphogenesis from veget ative to cyst cells. Furthermore, measurements of both in vitro and in vivo antioxidative activities of astaxanthin clearly demonstrated that tolerance to excessive reactive oxygen species is greater in astaxanthin-rich cysts than in astaxanthin-poor cysts or astaxanthin-less vegetative cells. Therefore, reactive oxygen species are involved in the regulation of both algal morph O-genesis and carotenogenesis, and the accumulated astaxanthin in cysts can function as a protective agent against oxidative stress damage. In this study, the physiological roles of astaxanthin in stress response and cell protection are reviewed.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.821-831
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• 2006

Unicellular green algae of the genus Haematococcus have been studied extensively as model organisms for secondary carotenoid accumulation. Upon environmental stress, such as strong irradiance or nitrogen deficiency, unicellular green algae of the genus Haematococcus accumulate secondary carotenoids in vesicles in the cytosol. Because secondary carotenoid accumulation occurs only upon specific environmental stimuli, there is speculation about the regulation of the biosynthetic pathway specific for secondary carotenogenesis. Because the carotenoid biosynthesis pathway is located both in the chloroplast and the cytosol, communication between both cellular compartments must be considered. Recently, the induction and regulation of astaxanthin biosynthesis in microalgae received considerable attention because of the increasing use of this secondary carotenoid as a source of pigmentation for fish aquaculture, as a component in cancer prevention, and as a free-radical quencher. This review summarizes the biosynthesis and regulation of the pathway, as well as the biotechnology of astaxanthin production in Haematococcus.

• 한국미생물·생명공학회지
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• 제46권2호
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• pp.114-119
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• 2018

Astaxanthin is one of the major carotenoids used in pigment has a great economical value in pharmaceutical markets, feeding, nutraceutical and food industries. This study was to increase the production of astaxanthin by co-expression with transformed Escherichia coli using six genes involved in the non-mevalonate pathway. Involved in the non-mevalonate biosynthetic pathway of the strain Kocuria gwangalliensis were cloned dxs, ispC, ispD, ispE, ispF, ispG, ispH and idi genes in order to increase astaxanthin production from the transformed E. coli. And co-expression with the genes to compared the amount of astaxanthin production. This engineered E. coli, containing both the non-mevalonate pathway gene and the astaxanthin biosynthesis gene cluster, produced astaxanthin at $1,100{\mu}g/g$ DCW (dry cell weight), resulting in approximately three times the production of astaxanthin.

• 생명과학회지
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• 제18권12호
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• pp.1764-1770
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• 2008

이 연구의 목적은 생물공학적으로 이소프레노이드 생합성 유전자를 클로닝하여 이들을 형질전환시킨 대장균을 제조하여 이들을 숙주로 사용하여 아스타잔틴의 생산을 증가시키는 것이다. 본 연구진은 선행연구에서 Paracoccus haeundaensis로부터 아스타잔틴 생산에 관여하는 6개의 아스타잔틴 생합성 유전자군을 보고하였고, 이들 유전자들을 발현 벡타(pCR-XL-TOPO-Crt)에 재조합한 후 이 벡터를 대장균에 형질 전환시켜서 건조중량으로 400 ${\mu}g$/g의 아스타잔틴을 생산하였다. 아스타잔틴의 생산성을 증가시키기 위해서 대장균으로부터 이소프레노이드 생합성 경로에 관여하는 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (lytB), farnesyl diphosphate (FPP) synthase (ispA), isopentenyl (IPP) diphossphate isomerase (idi) 유전자들을 클로닝하였고, 이들 유전자를 (pCR-XL-TOPOCrt-full)와 같이 대장균에 각각 공발현시켰다. idi 유전자와 아스타잔틴 생산에 관여하는 아스타잔틴 생합성 유전자군이 함께 형질 전환된 BL21(DE3) Codon Plus RIL 대장균를 배양하였을때, 건조중량으로 1,200 ${\mu}g$/g의 아스타잔틴을 생산하였다. 따라서 본 연구 결과, 이소프레노이드 생합성 유전자와 아스타잔틴 생합성 유전자군을 공발현 시킬 때 아스타잔틴의 생산이 3배 증가하였다.

• 한국미생물·생명공학회지
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• 제35권4호
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• pp.292-297
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• 2007

H. pluviails는 고광도와 질소 결핍 배지 조건에서 ketocarotenoid의 일종인 astaxanthin을 다량 축적하는 녹조류이다. 스트레스가 없는 조건에서 키운 green cell과 astaxanthin이 합성된 red cell을 HPLC를 통해 비교해 본 결과 각 색소의 양이 변화하는 것을 볼 수 있었다. 여러 ester 형태의 astaxanthin이 생합성 되고, zeaxanthin이 늘어난 반면, lutein과 ${\beta}$-carotene은 감소하였다. 또한 total chlorophyll 양이 줄어드는 대신 total carotenoid의 양이 늘어남을 보였다. H. pluvilalis에서 찾아낸 astaxanthin 생합성 경로에 있는 carotenoid hydroxylase, phytoene desaturase, isopentenyl pyrophosphate isomerase, ${\beta}$-carotene ketolase 유전자는 음성대조군인 chloroplast chlorophyll a-b binding protein와는 달리cell이 성장하기 좋은 조건의 상태보다 astaxanthin을 생합성하기 위해 고광도의 스트레스를 받았을 때 더 높은 발현양상을 보이는 것을 확인할 수 있었다.

• 생명과학회지
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• 제25권12호
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• pp.1339-1346
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• 2015

본 연구는 카로티노이드 생합성 유전자군이 형질전환된 Escherichia coli에서 archaea chaperonin을 공발현 시킴으로 카로티노이드의 생산량을 증대시키는 것이 목표이다. 카로티노이드는 식물, 박테이라, 조류 등이 생합성하는 노란색, 오렌지색, 붉은색 계통의 색소로 이들은 식품 또는 양식 사료로 주로 이용되는 물질이다. 본 연구자들은 선행연구를 통하여 Paracoccus haeundaensis로부터 카로티노이드 유전자군을 cloning하였고 이들 유전자군의 생화학 및 효소학적 기능성을 분석하는 연구 결과와 카로티노이드 생합성 유전자군(crtE, crtB, crtI, crtY, crtZ, crtW, crtX)을 대장균에 형질전환하여 400 μg/g dry cell weight (DCW)의 아스타잔틴을 생산하는 연구 결과를 보고 하였다. 본 연구에서는 이들 유전자군과 archaea chaperonin을 공발현시켜 대장균에서 astaxanthin을 890 μg/g dry cell weight (DCW)로 생산하였으며, 이는 선행 연구된 결과 보다 약 2배 이상의 astaxanthin 생산량을 향상 시키는 연구 결과이다.

• Journal of Microbiology and Biotechnology
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• 제28권12호
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• pp.2019-2028
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• 2018

Natural astaxanthin mainly derives from a microalgae producer, Haematococcus pluvialis. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production. However, the different responses to light intensity and nitrogen starvation needed to be analyzed for biomass growth and astaxanthin accumulation. The results showed that the highest level of astaxanthin production was achieved in nitrogen starvation, and was 1.64 times higher than the control group at 11 days. With regard to the optimization of light intensity utilization, it was at $200{\mu}mo/m^2/s$ under nitrogen starvation that the highest astaxanthin productivity per light intensity was achieved. In addition, both high light intensity and a nitrogen source had significant effects on multiple indicators. For example, high light intensity had a greater significant effect than a nitrogen source on biomass dry weight, astaxanthin yield and astaxanthin productivity; in contrast, nitrogen starvation was more beneficial for enhancing astaxanthin content per dry weight biomass. The data indicate that high light intensity synergizes with nitrogen starvation to stimulate the biosynthesis of astaxanthin.

• KSBB Journal
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• 제15권2호
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• pp.125-133
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• 2000

Astaxanthin의 산업적인 생합성을 위하여 wild type인 P.rhodozyma B30 효모를 UV, NTG 등으로 돌연변이 처리하여 0.5 mM $\beta$-ionone이 포함된 선별배지에서 carotenoids 합성능력이 우수한 변이주 B76을 분리하였다. 변이주 B76은 wild type과 비교시 균체 생성능력은 큰 차이가 없었으나 carot-enoids 합성능력은 40% 이상, astaxanthin 합성능력은 50% 이상 향상되었다. 선별된 변이주 B76의 최적 발효배지 및 배양 조건 선정을 위한 플라스크 배양실험 결과 최적 탄소원으로 glucoserk, 최적 질소원은 CSL : (NH4)2SO4 : yeast extract = 6 : 2 : 0.1이 혼합된 배지가 선정되었다. C/N ratio는 1.7~2.0 범위에서 유사한 발효성능을 보았으며(산업적인 생산성을 고려하여 2.0을 최적으로 선정), 배양온도는 $22^{\circ}C$가 최적이었다. 초기 pH는 가장 높은 세포농도를 나타낸 6.0을 최적으로 하였다. 종균 접종량은 전반적으로 균체량과 carotenoids 합성능력에는 영향을 미치지 않았으며 산업적인 생산성을 고려하여 3%(v/v) 수준이 적절한 것으로 사료되었다. 이와 같이 플라스크 배양을 통해 확립된 최적 배지 및 배양조건을 기초로 5 L 발효조를 이용한 회분식 배양실험을 통해 탄소원의 최적 농도는 18%임을 확인하였다. 특히 B76 변이주는 22%(w/v)까지의 고농도 glucose 존재하에서는 catabolite rep-ression을 받지 않는 것으로 나타났다. 용존산소가 부족한 경우에는 균체성장 및 색소합성이 저해되었고, 따라서 통기속도 1.0 v/v/m, 교반속도 400 rpm 이상을 유지함이 필요하였다. B76 세포는 배양 3일차에 exponential phase에 진입한 후(최대 Yx/s = 0.37) 배양 4일차에 stationary phase에 도달하였다. Carotenoids 및 astaxanthin 생합성은 세포성장이 정지한 후인 배양 5일차에 급격하게 증가하는(최대 Yp/s = 1.08) 전형적인 mixed-growth-associated 형태를 나타냈다. 이는 exp-onential phase 동안 급격한 균체성장으로 용존산소가 부족하여 NADH balance에 의해 astaxanthin 생합성 경로 중 탈수소화 단계가 저해되기 때문으로 사료되었다. 최종 세포농도는 43.3 g/L, 단위부피당 carotenoids 함량은 149.4 mg/L, astaxanthin 함량은 110.6 mg/L로서 산업적인 생산성이 있는 것으로 나타났다. 이번 연구를 통하여 개발된 변이주 B76 및 이의 대량 발효를 위한 최종조건의 정립은 향후 astaxanthin의 산업적 생산공정에 필요한 기초자료로 이용될 것으로 기대된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권4호
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• pp.263-274
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• 2000

Carotenoids are widely distributed natural pigments which are in an increasing demand by the market, due to their applicatins in the human food, animal feed, cosmetics, and pharmaceutical industries. Although more than 600 carotenoids have been identified in nature, only a few are industrially important (${\beta}$-carotene, astaxanthin, lutein or lycopene). To date chemical processes manufacture most of the carotenoid production, but the interest for carotenoids of biological origin is growing since theire is an increased public concern over the safety of artificial food colorants. Although much interest and effort has been devoted to the use of biological sources for industrially important carotenoids, only the production of biological ${\beta}$-carotene and astaxanthin has been reported. Among fungi, several Mucorales strains, particularly Blakeslea trispora, have been used to develop fermentation processes for the production of ${\beta}$-carotene on almost competitive cost-price levels. Similarly, the basidiomycetous yeast Xanthophyllomyces dendrorhous (the perfect state of Phaffia rhodozyma), has been proposed as a promising source of astaxanthin. This paper focuses on recent findings on the fungal pathways for carotenoid production, especially the structure and function of the genes involved in the biosynthesis of carotenoids in the Mucorales. An outlook of the possibilities of an increased industrial production of carotenoids, based on metabolic engineering of fungi for carotenoid content and composition, is also discussed.