Cultivation of Chlorella protothecoides in photobioreactors: The combined impact of photoperiod and CO₂ concentration

Abstract

Algal biomass is regarded as an alternative source for producing renewable fuels, given the chemical nature of storage products: lipids, starch, and proteins. Many factors affecting the production of microalgal biomass and lipid accumulation include the light and CO2 concentration, i.e. critical factors for determination of the biochemical composition of microalgal biomass. Our objective was to evaluate the effect of three different light/dark photoperiods (12/12 h, 16/8 h, 24/0 h) and the CO2 concentration (from air and 5% v/v CO2‐enriched air) on the growth rate, productivity, and changes in the biochemical composition of Chlorella protothecoides biomass. Continuous illumination stimulated growth under supplementation of air CO2. At 5% CO2, the maximum C. protothecoides growth rate was found under 16/8 light/dark cycles and longer duration of light yielded a decrease in the specific growth rate. The photoperiods and CO2 concentrations influenced the biomass productivity. Chlorella protothecoides produced biomass more efficiently at the 24/0 and 16/8 light/dark cycles under supplementation of air CO2 than at addition of 5% CO2. However, under the 12/12 light/dark cycle, biomass productivity was higher at 5% CO2. The light photoperiod greater than 16 h did not increase biomass productivity. These factors also influenced the content of lipids and carbohydrates. A maximal lipid content was observed for the 24‐h photoperiod for air CO2, whereas the addition of 5% CO2 affected lipid and carbohydrate production.

Agro-industrial by-product in photoheterotrophic and mixotrophic culture of Tetradesmus obliquus: Production of ω3 and ω6 essential fatty acids with biotechnological importance

“…The differences in the results of the cell lipid content are a consequence of the method used for the analysis. The Bligh & Dyer extraction method is used for all extractable compounds in solvents, including chlorophyll 39 , and the FTIR determination of the lipid content was based on the stretching vibration www.nature.com/scientificreports www.nature.com/scientificreports/ band of the methylene group (CH 2 ) characteristic for lipids 40 . This study indicates that the photoheterotrophic and mixotrophic culture of T. obliquus provided the cells with optimal environmental conditions and all necessary biogenic elements, mainly carbon and nitrogen without inducing stress, which results in reduced lipid content.…”

“…In total, 9 spectra were obtained for each cultivation variant. The spectra were normalized to the amide I band at 1640 cm −1 ,which is the most intense band and, on their basis, the mean representative FT-IR spectrum was determined for each variant of the culture 40 . The content of carbohydrates and lipids in the biomass was assessed by determination of the intensity of the sugar band (1025 cm −1 ) to the protein band (amide I band − 1640 cm −1 ) and the ratio of the intensity of the lipid band (2917 cm −1 ) to the protein band (amide I band − 1640 cm −1 ).…”

Characterization, Bioactive Properties and Antifungal Activity of Chlorella protothecoides Microalgae Oil

“…FTIR spektroskopisi tek bir numunede hücre biyokimyasal bileşiminin (proteinler, lipitler, nükleik asitler ve karbonhidratlar) eşzamanlı olarak belirlenmesi imkanı sunar [23].…”

“…FTIR spektrumlarından tanımlanan fonksiyonel gruplar, Tablo 2'de gösterilmiştir. C. protothecoides örneğinde görülen 900-1800 cm −1 pikleri karbonhidrat -protein içeriğinden kaynaklanmaktadır [23]. 1743 cm −1 noktasında görülen spektral bant protein yapılarının N-H eğilme vibrasyonlarıyla ilişkilidir.…”

“…2853-2922 cm −1 aralığında görülen bantlar CH2'nin C − H titreşim gerilmesi ile ilişkilidir. C. protothecoides örneğinde görülen 2800-3000 cm −1 (Tablo 2) pikleri lipit içeriğinden kaynaklanmaktadır [23]. Yapılan çalışmalarda, mikroalglerin içeriğindeki proteinler, polisakkaritler, lipidler, vitaminler, enzimler, steroller ve diğer değerli metabolitlerin antimikrobiyal ve antioksidan özellik gösterdiği belirtilmiştir [7].…”