Assessment of stress conditions for carotenoids accumulation in Chlamydomonas reinhardtii as added-value algal products

Abstract

Background: 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. 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. Results: The 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. Conclusions: High 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.

Evaluation of growth and carotenoid production by a green microalga Scenedesmus quadricauda PUMCC 4.1.40. under optimized culture conditions

“…Among different intensities of light, the growth of the test organism increased by 2.58‐fold when illuminated continuously with 60 µE of white light (Figure 5). The green microalga Chlamydomonas reinhardtii cultivated in column photobioreactor illuminated with irradiance of 149 µmol/m 2 /s accumulated maximum amount of carotenoids equivalent to 2.15 g/L biomass [43]. White light is reported to support more growth as it has a range of radiations required for optimal photosynthesis as reported for other microalgae [18,30,44].…”

“…Erdoğan et al [51] reported 0.14% vialoxanthin, 0.24% lutein, 0.015% α‐carotene, and 0.055% β‐carotene in Scenedesmus protuberans . On the contrary, the microalga C. reinhardtii produced 0.85 mg/g astaxanthin, 0.87 mg/g lutein, and 0.64 mg/g β‐carotene [43]. Gong and Bassi [17] reported production rate of 11.98 mg lutein/g dries biomass/day in Chlorella vulgaris UTEX 265 in a photobioreactor.…”

Impact of Light Stress on the Synthesis of Both Antioxidants Polyphenols and Carotenoids, as Fast Photoprotective Response in Chlamydomonas reinhardtii: New Prospective for Biotechnological Potential of This Microalga

“…For this microalga, the response to exposure to different stress in combination with light stress has been widely investigated particularly in association with the induction of carotenoids synthesis [29][30][31][32]. This aspect emerged from the trend of changes of chlorophyll content in the cultures.…”

“…The induction of photo-protective responses in an outdoor photobioreactor has already been shown in the strain CC124, which was able to synthesize a considerable content of zeaxanthin during the process of hydrogen production [15]. Although the physiology of C. reinhardtii is well known, the studies carried out for the application of this microalga mainly concerned the improvement of hydrogen production efficiency [25,27], and the changes in the chlorophyll fluorescence for monitoring different kinds of stress, particularly photo-oxidative stress, such as high light exposure and anaerobiosis [28][29][30][31]. Some studies have dealt with the use of its exhausted biomass after H 2 production, as biochar [47].…”

Responsible Innovation in Industry: The Role of Firm’s Multi-Stakeholder Network

“…Cellulose-containing algae can be used as a renewable feedstock for bioethanol production -although algae are generally known for their low cellulose and hemicellulose content, they have enough sugar content to be fermented for bioethanol production (El-Mekkawi et al, 2019b).…”