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- Tez No: 797960
- Danışmanlar: Belirtilmemiş.
- Tez Türü: Yüksek Lisans
- Konular: Belirtilmemiş.
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2023
- Dil: İngilizce
- Üniversite: Instıtute Of Chemıcal Technology In Prague
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
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Özet (Çeviri)
Within many microalgae species, Chlorella is known for its high nutritional content, valuable metabolites and health benefits it provides. For commercial applications, Chlorella mostly grown in open systems, which have severe drawbacks. Therefore, alternative cultivation methods based on heterotrophy are used for large scale production of biomass and high value secondary metabolites. This master thesis is focused on carotenoids production from chlorophyll deficient Chlorella strains using batch heterotrophic cultivation as a novel strategy to make the separation of carotenoids easier. For this purpose, 5 Chlorella sp. strains were first tested on their ability to use glucose as substrate for fermentation and compared to the established chlorophyll less strain Chlorella G11, obtained from culture collection, as well as on their ability to undergo UV mutation. In an extensive set of experiments, a proper UV light exposure was established to generate random mutations. The UV exposure was then applied to selected Chlorella H14 strain and applied 3 times with subsequent phenotypic selection with flow cytometry, using a newly developed separation procedure based on chlorophyll fluorescence. A mutant Chlorella strain assigned as C1 obtained as a promising alternative for heterotrophic cultivation in higher substrate concentration similar to its parental strain Chlorella H14. However, C1 mutant while designated as chlorophyll-deficient, still contains considerable levels of chlorophyll and will therefore require further steps of mutagenesis and selection. To achieve maximum biomass and carotenoid productivity, the Chlorella G11 strain was selected and tested using cross gradient of temperature and light intensities under normal and under nitrogen limiting growth conditions. The maximum percentage of carotenoid to total mass in dry biomass was observed in the range of 20-28°C and light exposure of 350-450 µE/m2 s under nitrogen starvation.
