Abstract
BackgroundMicroalgae, the third-generation source of biofuel have invaluable bio-refineries such as carotenoids. The accumulation of carotenoids in the algal cell is based on several parameters during algal growth. Some of these parameters are irradiance and cultivation periods which figures the photoperiod during algal growth. In this work, 0.6 g/L Chlamydomonas reinhardtii, green algae strain, was cultivated using the BG-11 medium in bubble column photobioreactor illuminated by white cool fluorescent 24 h per day, irradiance range 40.5–149 μmol.m−2.s−1, and cultivation period range 10–20 days. The carotenoids were extracted using two solvents, petroleum ether, and ethyl acetate in ratio 7:3. The carotenoids fractions were quantified using HPLC and the design expert program 8.6 was used to optimize the irradiance and cultivation period in order to gain maximum carotenoids accumulation in C. reinhardtii using response surface method.ResultsThe results revealed that the optimum conditions of C. reinhardtii cultivation are illuminating the culture 24 h a day for 10 days with irradiance 149 μmol.m−2.s−1 producing 0.85 mg/g astaxanthin, 0.87 mg/g lutein, and 0.64 mg/g β-carotene, as a maximum value of accumulating carotenoids in 2.15 g/L biomass yield.ConclusionsHigh irradiance and cultivation period are two essential parameters for accumulating carotenoids in algae. Response surface method is an affordable method to optimize these parameters simultaneously via predicting a model describe the relation and analyze the results statistically. The experimental verification of results proved the model’s validity. The prospective research is going to study the effect of more parameters on carotenoids accumulation in algae.
Highlights
Microalgae, the third-generation source of biofuel have invaluable bio-refineries such as carotenoids
The statistical analysis of astaxanthin content response revealed that the regression coefficient (R2) was 0.99, whereas the predicted Regression coefficient (R2) was 0.95 and the adjusted R2 was 0.98 with a coefficient of variation (CV) 10.53
The statistical analysis of each astaxanthin response, lutein response, and β-carotene response revealed that the predicted R2 is in reasonable agreement with the adjusted R2
Summary
Microalgae, the third-generation source of biofuel have invaluable bio-refineries such as carotenoids. The accumulation of carotenoids in the algal cell is based on several parameters during algal growth. Some of these parameters are irradiance and cultivation periods which figures the photoperiod during algal growth. The carotenoids fractions were quantified using HPLC and the design expert program 8.6 was used to optimize the irradiance and cultivation period in order to gain maximum carotenoids accumulation in C. reinhardtii using response surface method. Carotenoids are characterized by energetic metabolism, which ensures a variety of secondary metabolites products (Ahmed et al 2014). Their benefits in human health were conclusively proved, and this led to open novel uses for some carotenoids (Thomas and Kim 2013). The oxygen group expresses the kind of carotenoids, e.g.; OHgroups indicate lutein, while the oxi-groups signify
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