Pigment Production under Cold Stress in the Green Microalga Chlamydomonas reinhardtii

Abstract

Microalgae have long been used for the commercial production of natural colorants such as carotenoids and chlorophyll. Due to the rising demand for carotenoids and other natural products from microalgae, strategies to increase production efficiency are urgently needed. The production of microalgal biorefineries has been limited to countries with moderate climates. For countries with cooler climates and less daylight, methodologies for the efficient production of microalgal biorefineries need to be investigated. Algal strains that can be safely consumed as whole cells are also attractive alternatives for developing as carotenoid supplements, which can also contain other compounds with health benefits. Using such strains helps to eliminate the need for hazardous solvents for extraction and several other complicated steps. In this study, the mesophilic green alga Chlamydomonas reinhardtii was employed to study the effects of cold stress on cell physiology and the production of pigments and storage compounds. The results showed that temperatures between 10 and 20 °C induced carotenoid and chlorophyll accumulation in the wild-type strain of C. reinhardtii. Interestingly, the increased level of carotenoids suggested that they might play a crucial role in cold stress acclimation. A temperature of 15 °C resulted in the highest carotenoid and chlorophyll productivity. At this temperature, carotenoid and chlorophyll productivity was 2 times and 1.3 times higher than at 25 °C, respectively. Subjecting a mutant defective in lutein and zeaxanthin accumulation to cold stress revealed that these two carotenoids are not essential for cold stress survival. Therefore, cold temperature could be used as a strategy to induce and increase the productivity of pigments in C. reinhardtii.

Bio-removal of rare earth elements from hazardous industrial waste of CFL bulbs by the extremophile red alga Galdieria sulphuraria

“…All the members of cyanidiophyceae were considered as best organisms for the production of stable phycobiliproteins ( Carfagna et al, 2018 ; Ferraro et al, 2020 ). Regarding carotenoids, their function also comprises a defense mechanism to mitigate the damaging effects of stress in photosynthetic organisms ( Shi et al, 2020 ; Potijun et al, 2021 ). Microalgae respond to an increased exposure to dissolved metals by accumulating carotenoids as antioxidant compounds ( Gauthier et al, 2020 ).…”

Mineral Solubilizing Microorganisms (MSM) and their Applications in Nutrient Bioavailability, Bioweathering and Bioremediation, Volume II

“…All the members of cyanidiophyceae were considered as best organisms for the production of stable phycobiliproteins (Carfagna et al, 2018;Ferraro et al, 2020). Regarding carotenoids, their function also comprises a defense mechanism to mitigate the damaging effects of stress in photosynthetic organisms (Shi et al, 2020;Potijun et al, 2021). Microalgae respond to an increased exposure to dissolved metals by accumulating carotenoids as antioxidant compounds (Gauthier et al, 2020).…”

Chlamydomonas reinhardtii: A Factory of Nutraceutical and Food Supplements for Human Health

“…The bioaccumulation of heavy metals represents another significant problem; thus, microalgae-growing media and water should always be carefully controlled [ 4 ]. It is worth noting that most of the processes used in microalgae production still struggles to reach a technology readiness level (TRL) that could demonstrate industrial viability, even if there is a significant number of new studies that provide important supplementary knowledge to that end (e.g., culture illumination influencing microalgal physiology, gene expression, and metabolism) [ 5 ]. For those cases that do not include whole-cell consumption, usually, the nutritional components of microalgae are extracted before being used.…”

“…The role of C. reinhardtii in developing genetic engineering protocols has been essential, and nowadays it is widely used to maximize the yields of bio-products, such as polyphenols, catechin, flavanols, glycosides, and phlorotannins, with intriguing applications in both medical and nutraceutical fields [ 17 , 18 , 19 , 20 ]. The abundance of noteworthy compounds produced by C. reinhardtii as primary or secondary metabolites made it an attractive source of carotenoids, chlorophylls lipids, polysaccharides, and recombinant proteins [ 5 , 21 ]. The recently discovered ability of C. reinhardtii to grow rapidly in fermenters has opened up the way for production at a commercial scale [ 22 ].…”