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Diep Ngoc Pham,김창준 한국생물공학회 2021 Biotechnology and Bioprocess Engineering Vol.26 No.4
5-aminolevulinic acid (ALA) has extensive use in photodynamic cancer therapy, tumor diagnosis, and agriculture. In the microbial production of ALA, most efforts have focused on engineering enzymes and the metabolic pathways involved in ALA biosynthesis. The aim of this study was to enhance ALA production using recombinant Streptomyces coelicolor expressing the ALA synthase gene (hem A) of Rhodobacter sphaeroides with a novel two-stage pH control strategy. Batch cultures were performed in production medium at different pH values. Although cells grew well at neutral pH (6.8-7.2), the highest amount of ALA was produced with a long culture time (140 h) at a weakly acidic pH (5.5-6.0). In response, a two-stage pH control strategy was developed in which pH was maintained at 6.8-7.2 for cell growth and then shifted to 5.5-6.0 to promote ALA synthesis, resulting in a significant enhancement in ALA production compared to a one-stage pH control strategy. The titer of ALA was further improved up to 482 mg/L in the two-stage pH culture by supplying more glucose in the medium and shifting the pH during the early phase of cultivation.
ALMA OBSERVATIONS OF W HYDRAE: IMPACT OF MISSING BASELINES
Do Thi Hoai,Tuan-Anh Pham,Pham Tuyet Nhung,Pierre Darriulat,Pham Ngoc Diep,Nguyen Bich Ngoc,Tran Thi Thai 한국천문학회 2021 Journal of The Korean Astronomical Society Vol.54 No.6
The lack of short baselines, referred to as the short-spacing problem (SSP), is a well-known limitation of the performance of radio interferometers, causing a reduction of the flux detected from source structure on large angular scales. The very large number of antennas operated in the Atacama Large Millimeter/sub-millimeter Array (ALMA) generates situations for which the impact of the SSP takes a complex form, not simply measurable by a single number, such as the maximal recoverable scale. In particular, extended antenna configurations, complemented by a small group of closeby antennas at the centre of the array, may result in a double-humped baseline distribution with a significant gap between the two groups. In such cases one should adopt as the effective maximal recoverable scale the one associated with the extended array and use only the central array to recover missing ux, as one would do with single dish or ACA (Atacama Compact Array) observations. The impact of the missing baselines can be very important and may easily be underestimated, or even overlooked. The present study uses ALMA archival data of the ^{29}SiO(8-7) line emission of the AGB star W Hydrae for a demonstration. A critical discussion of the reliability of the observations away from the star is presented together with comments of a broader scope. Properties of the circumstellar envelope of W Hya within ~15 au from the star, many of which are not mentioned in the published literature, are briefly described and compared with R Doradus, an AGB star having properties very similar to W Hya.
폐글리세롤을 탄소원으로 hemA와 otsBA를 공동 발현하는 재조합 대장균 배양을 통한 아미노레블린산 생산
염정미 ( Jingmei Yan ),디엡느구팜 ( Diep Ngoc Pham ),강대경 ( Dae Kyung Kang ),김성배 ( Sung Bae Kim ),김창준 ( Chang Joon Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2016 한국미생물·생명공학회지 Vol.44 No.3
본 연구는 폐글리세롤을 탄소원으로 사용하여 생장저해 없이 아미노레블린산(ALA)을 생산하는 미생물 공정을 개발하는데 그 목적이 있다. 폐글리세롤이 첨가된 배지에서 ALA 생산균주(E. coli/pH-hemA)를 배양하여 얻은 세포밀도와 ALA 생산량은 순수 글리세롤이 첨가된 배지에서 얻은 값보다 각각 1.8배와 1.2배 낮았다. 트레할로스를 첨가(30 g/l 또는 100 g/l) 함에 따라 세포생장과 ALA 생산성이 향상되었다. otsBA를 공동 발현하는 엔지니어링 균주(E. coli/pHhemA/ pS-otsBA)를 제작하여 순수 또는 폐글리세롤이 첨가된 배지에서 그 성능을 평가하였다. 폐글리세롤이 함유된 배지에서 엔지니어링 균주의 세포생장 및 생산성을 향상시키기 위하여 IPTG의 최적 첨가농도 및 시기를 결정하였다. 지수생장 초기에 0.6 mM의 IPTG를 첨가한 배양에서 세포 생장과 ALA 생산량이 최대치를 나타내었다. 이때 얻은 OD600(세포 밀도)와 ALA 농도는 각각 16과 2,121 mg/l였는데, 이는 순수 글리세롤이 첨가된 배지에서 얻은 생산량과 비슷한 값이다. 본 결과는 ALA 생산균주에서 트레할로스 생합성 오페론의 최적 공동 발현을 통해 폐글리세롤에 대한 저항성을 높임으로써 추가적인 전처리 없이 폐글리세롤을 탄소원으로 직접 사용할 수 있음을 보여준다. This study aimed to develop a microbial process for producing aminolevulinic acid (ALA) using crude glycerol. In the culture of ALA-producing cells (Escherichia coli/pH-hemA) in a medium containing crude glycerol, the cell density and production were 1.8-fold and 1.2-fold lower than those obtained from pure glycerol, respectively. However, the cell growth and production were improved by supplementing the medium with trehalose (30 or 100 g/l). Engineered cells (E. coli/pH-hemA/pS-otsBA) were constructed to express otsBA and their culture performance was compared with that of control cells (E. coli/pH hemA/ pSTV28). The effects of isopropyl β-D-1-thiogalactopyranoside (IPTG) concentration and the time of induction were examined to improve the cell growth and ALA production in engineered cells cultured using crude glycerol. When 0.6 mM of IPTG was added at the beginning of the exponential growth phase, the ALA produced by cells was 2,121 mg/l, which was comparable to that from pure glycerol. The results demonstrate that otsBA expression endowed cells with the capacity to tolerate the toxicity of crude glycerol for direct use.
Nu Thi Tran,Diep Ngoc Pham,Chang Joon Kim 한국생물공학회 2019 Biotechnology and Bioprocess Engineering Vol.24 No.3
Over the past two decades, intensive efforts have been made to construct recombinant Escherichia coli or Corynebacterium glutamicum by engineering C4 or C5 pathways to improve microbial production of 5aminolevulinic acid (ALA), which has medical application for photodynamic cancer therapy and tumor diagnosis. In this study, we explored the feasibility of enhanced production of ALA by expressing C4 pathway enzyme, ALA synthase, in Streptomyces coelicolor, and medium optimization. The hemA from Rhodobacter sphaeroides was successfully integrated into the chromosome of Streptomyces coelicolor by conjugal transformation, and recombinant Streptomyces cells expressed well the foreign hemA. Glucose promoted ALA synthesis, and yeast extract showed a strong positive effect on ALA production. Optimization of casamino acid, peptone, malt extract, glycine, and succinic acid increased the product titer. In flask cultures, cell growth and ALA production of recombinant Streptomyces were 2.3 and 3.0-fold higher, respectively, in optimal medium than those of control. The maximum ALA, 137 mg/L, was obtained at 28 h in bioreactor culture, in which 3.1-fold higher cell mass and 2.9-fold greater volumetric productivity were achieved, compared to those in flask cultures.
Tran Huu Dat,Uyen Diep Pham Phuong,Anh Do Thi Ngoc 한국언론학회 2023 Asian Communication Research Vol.20 No.3
While CETSCALE has frequently been tested and applied in Western contexts, it has received little attention in Asian countries, particularly Vietnam, a developing country that has one of the highest economic growth rates worldwide (DablaNorris & Zhang, 2021). Hence, the current study employs CETSCALE to examine the effects of nationalistic advertisements on consumer ethnocentrism and purchase intention for the domestic VinFast electric vehicles and Bphone smartphones among Vietnamese millennial consumers. Results based on 206 survey responses (N = 206) suggested the predictive powers of respondents’ attention and exposure to nationalistic advertisements on their perceptions of the advertisements which, in turn, predicted consumer ethnocentrism level and domestic buying intention. Perceptions of nationalistic advertisements particularly played a quintessential role in predicting consumers' ethnocentrism and, eventually, buying intentions for domestic EVs and smartphones. The study is one of the first attempts to examine the influence of nationalistic advertisements (e.g., exposure and attention), in relation to CETSCALE, on buying intentions, looking at two different product categories (i.e., EVs and smartphones). Furthermore, it contributed to the globalization and de-Westernization of media mass communication scholarship by testing CETSCALE in the understudied context of Vietnam. Theoretical and empirical implications, for instance, employment strategies for nationalistic advertising, were provided.
김유근(You Geun Kim),디엡느구팜(Diep Ngoc Pham),이영훈(Yeong Hun Lee),조지중(Ji Joong Jo),최은영(Eun Yong Choe),이용현(Young Hyeon Lee),김성배(Sung Bae Kim),김창준(Chang-Joon Kim) 한국청정기술학회 2017 청정기술 Vol.23 No.4
본 연구에서 아카시아꽃잎을 기질로 미백효과와 항산화효과가 우수한 천연물질을 생산하는 플라스크 발효법을 개발하였다. 아카시아꽃잎 추출액은 tyrosinase 활성을 저해하지 않은 반면, 2년 전통발효액과 2년 전통발효액을 접종한 아카시아꽃잎 플라스크 발효액은 tyrosinase 활성을 저해하였다. 아카시아꽃잎 플라스크 발효농축액 10% 포함된 용액의 tyrosinase 활성 저해율은 40%였고 농축액 함량이 증가할수록 저해율도 증가하였다. 양성대조군인 알부틴(20 mg mL<SUP>-1</SUP>)과 코직산(80 μg mL<SUP>-1</SUP>)의 tyrosinase 활성 저해율은 각각 90%와 58%였다. 이는 플라스크 발효농축액 40%가 포함된 용액의 미백성능이 코직산(80 μg mL<SUP>-1</SUP>)의 성능과 비슷함을 보여준다. 농축액이 20% 포함된 용액의 항산화활성은 56%였고 농도가 증가할수록 용액의 항산화활성도 점차 증가하여 농축액이 60% 포함된 용액의 항산화활성은 98%였다. 이는 항산화효과가 우수한 비타민 C수용액(10 mg mL<SUP>-1</SUP>)과 동일한 항산화능력이다. 모든 농도의 발효농축용액에서 95% 이상의 세포생존율을 나타내어 발효액은 독성이 없는 것으로 판명되었다. 실온에 보관된 아카시아꽃잎 발효상등액은 pH와 당도 변화가 없었고 분리, 변색, 및 변취 등의 관능적 성상의 변화가 없는 안정한 상태를 유지하였다. 본 결과는 아카시아꽃잎 플라스크 발효액이 안전하고 미백 및 항산화효과가 뛰어나 미백화장품 원료로 사용가능함을 보여준다. 이는 본 연구를 통하여 아카시아꽃잎 발효기간을 획기적으로 단축시킨 배양방법이 개발되었음을 시사한다. This paper describes a shake-flask fermentation of Acacia flower producing whitening- and antioxidant- agents. Tyrosinase activity was inhibited in the presence of traditional and flask-fermentation broths whereas no inhibitory effect of flower extract was observed. Tyrosinase inhibition was 40% in the presence of solution containing 10% of extract from fermentation broth and it increased by increase in the concentration of it. Arbutin (20 mg mL<SUP>-1</SUP>) and kojic acid (80 μg mL<SUP>-1</SUP>) gave 90% and 58% inhibition, respectively. The result indicates that whitening activity of 40% extract solution was comparable to that of kojic acid (80 μg mL<SUP>-1</SUP>). The comparable antioxidant activity was observed for 60% extract and 10-mg mL<SUP>-1</SUP> vitamin solution. No noticeable toxicity was observed with extract. The physicochemical stability of fermentation supernatant was observed at room temperature storage condition. The result clearly shows that shake-flask fermentation of Acacia flower produced whitening agent for functional cosmetics.