| 1. |
- Kim, Jung Hun, et al.
(författare)
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Production of β-carotene by recombinant Escherichia coli with engineered whole mevalonate pathway in batch and fed-batch cultures
- 2009
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Ingår i: Biotechnology and Bioprocess Engineering. - : Springer Science and Business Media LLC. - 1226-8372 .- 1976-3816. ; 14:5, s. 559-564
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant Escherichia coli engineered to contain the whole mevalonate pathway and foreign genes for β-carotene biosynthesis, was utilized for production of β-carotene in bioreactor cultures. Optimum culture conditions were established in batch and pH-stat fed-batch cultures to determine the optimal feeding strategy thereby improving production yield. The specific growth rate and volumetric productivity in batch cultures at 37°C were 1.7-fold and 2-fold higher, respectively, than those at 28°C. Glycerol was superior to glucose as a carbon source. Maximum β-carotene production (titer of 663 mg/L and overall volumetric productivity of 24.6 mg/L × h) resulted from the simultaneous addition of 500 g/L glycerol and 50 g/L yeast extract in pH-stat fed-batch culture.
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| 2. |
- Li, He, et al.
(författare)
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Quantitative analysis of valiolamine through pre-column derivatization with phenylisocyanate using high-performance liquid chromatography with UV detection : Selection of reagent, identification of derivative and optimization of derivatization conditions
- 2009
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier. - 0731-7085 .- 1873-264X. ; 49:4, s. 957-963
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Tidskriftsartikel (refereegranskat)abstract
- This report describes the improved quantitative determination of valiolamine in a medium for microbial culture using high-performance liquid chromatography with UV detection. Valiolamine aqueous solution was dried, dissolved in dimethyl sulfoxide and derivatization performances of phenylisocyanate (PHI), 1-fluoro-2,4-dinitrobenznene and 1-naphthylisothiocyanate were compared in the presence of triethylamine. The PHI was chosen as the most suitable derivatization reagent and the valiolamine-PHI derivative was identified by thin-layer chromatography and electrospray ionization mass spectrometry. The derivative eluted at 10.5 min on a reverse-phase column using a mobile phase composed of 10% acetonitrile in water containing 0.5 mM sodium octyl sulfate (pH 3.0), at a column flow rate of 1.0 mL/min with UV detection at 240 nm. The optimum conditions for derivatization were a reaction temperature of 30 degrees C, reaction time of 30 min, and PHI concentration higher than 33.6 mM. Calibration curves were linear in the range of 0.99-19.95 microg/mL for the standard solutions and 24.9-99.7 microg/mL for the spiked sample. The proposed method was validated and proven to be selective, accurate and precise and suitable for the quantitative analysis of valiolamine in medium for microbial cultures.
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