Browsing by Author "Hsieh, Sung-Yuan"

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Biomass and lipid production of a novel microalga, Chlorellaceae sp P5, through heterotrophic and swine wastewater cultivation
(2018-05-01)
Chiang, Yin-Ling
;
Chen, Yu-Pei
;
Yu, Ming-Chen
;
Hsieh, Sung-Yuan
;
Hwang, Ing-Er
A potential novel genus of microalgae was isolated from swine wastewater. According to a phylogenetic analysis of 18S rRNA and internal transcribed spacer (ITS) sequences, as well as the ITS2 secondary structure, this strain was designated as Chlorellaceae sp. P5. Acclimatization to various temperatures, pH conditions, and salinities demonstrated that this strain can grow at temperatures of 20 degrees C-40 degrees C, in an acidity range of pH 4-7, and with salinity as high as 3% NaCl. To optimize biomass production, response surface methodology was used which included variables associated with carbon and nitrogen sources. In this study, flask cultivation yielded 1.66 g l(-1) d(-1) of biomass under 15.19 g l(-1) glucose and 8.26 mM ammonium bicarbonate. The fatty acid composition suggested that the lipid from Chlorellaceae sp. P5 can be typically used for biodiesel production, with a low degree of unsaturated fatty acids. Moreover, a high content of the first-limiting amino acid (lysine) and 9,12-Octadecadienoic acid (linoleic acid, C18:2) for nutritional supplements was also observed. With respect to swine wastewater treatment, the isolated strain showed an excellent removal rate of ammonia and phosphate over 97.3 mg l(-1) of NH3-N and 20.3 mg of l(-1) PO43- in the sterilized and none-sterilized wastewater. The biomass and lipid derived from Chlorellaceae sp. P5 can be attained at 0.49 g l(-1) d(-1) and 0.13 g l(-1) d(-1) by swine wastewater cultivation with 5% CO2 supply, respectively. According to the various characteristic analyses, Chlorellaceae sp. P5 has great potential for different industrial developments such as biodiesel and wastewater treatment. Published by AIP Publishing.
Identification of the mokH Gene Encoding Transcription Factor for the Upregulation of Monacolin K Biosynthesis in Monascus pilosus
(2010-01-13)
Chen, Yi-Pei
;
Yuan, Gwo-Fang
;
Hsieh, Sung-Yuan
;
Lin, Yu-Shan
;
Wang, Wei-Yi
Monacolin K is a secondary metabolite synthesized by polyketide synthases (PKS) from Monascus. The monacolin K biosynthetic gene cluster, mokA-mokI, has been characterized in Monascus pilosus. The mokH gene encoding Zn(II)2Cys6 binuclear DNA binding protein is assumed to be an activator for monacolin K production. In this study, the mokH gene was cloned and driven by the glyceraldehyde-3-phosphate dehydrogenase (gpd) promoter for overexpression in M. pilosus. The transformants containing an extra copy of the mokH gene were obtained and verified by PCR and Southern hybridization. The transcripts of mokH in the transformants were expressed significantly higher than those of the wild-type strain. The transformants were stably inherited through the next generation, as determined by observation of the enhanced green fluorescent protein (EGFP). The transformant T-mokH1 also showed a 1.7-fold higher production of monacolin K than the wild-type strain in a time course analysis. Analysis of the RT-PCR products demonstrated that the monacolin K biosynthetic genes in the transformant were expressed to a greater extent than those in the wildtype strain. These results indicated that mokH upregulated the transcription of monacolin K biosynthetic genes and increased monacolin K production.