Photosynthesis of the Cyanidioschyzon merolae cells in blue, red, and white light

Abstract

Photosynthesis and respiration rates, pigment contents, CO2 compensation point, and carbonic anhydrase activity in Cyanidioschizon merolae cultivated in blue, red, and white light were measured. At the same light quality as during the growth, the photosynthesis of cells in blue light was significantly lowered, while under red light only slightly decreased as compared with white control. In white light, the quality of light during growth had no effect on the rate of photosynthesis at low O2 and high CO2 concentration, whereas their atmospheric level caused only slight decrease. Blue light reduced markedly photosynthesis rate of cells grown in white and red light, whereas the effect of red light was not so great. Only cells grown in the blue light showed increased respiration rate following the period of both the darkness and illumination. Cells grown in red light had the greatest amount of chlorophyll a, zeaxanthin, and β-carotene, while those in blue light had more phycocyanin. The dependence on O2 concentration of the CO2 compensation point and the rate of photosynthesis indicate that this alga possessed photorespiration. Differences in the rate of photosynthesis at different light qualities are discussed in relation to the content of pigments and transferred light energy together with the possible influence of related processes. Our data showed that blue and red light regulate photosynthesis in C. merolae for adjusting its metabolism to unfavorable for photosynthesis light conditions.

The carbon-concentrating mechanism of the extremophilic red microalga Cyanidioschyzon merolae

“…In b , the measured and literature values represent the cellular , while the calculated values represent the rubisco K c . The literature data sources are Zenvirth et al ( 1985 ); Rademacher et al ( 2016 ); Parys et al ( 2021 ), which report oxygen evolution data across external pH 1.5–7.5, oxygen evolution data from cells grown under 5% CO 2 and exposed to ambient CO 2 concentrations for 24 h, and a compensation point measurement at 21% O 2 , respectively …”

“…CCMs by definition substantially accumulate intracellular inorganic carbon, as is detectable in C. merolae (Zenvirth et al 1985 ) . However, the existence of the CCM in C. merolae is uncertain due to the necessity of a functional photorespiratory pathway in this alga and to variation in this alga’s CO 2 compensation point with O 2 concentration (Rademacher et al 2016 ; Parys et al 2021 ). Here we show that C. merolae exhibited CO 2 uptake characteristics that are unlikely to be explained by rubisco’s kinetic properties alone.…”

Enhancing Phycoerythrin and Phycocyanin Production from Porphyridium cruentum CCALA 415 in Synthetic Wastewater: The Application of Theoretical Methods on Microalgae

“…On the other hand, while blue light had the highest PC concentration (1.25 nmol 10 -8 cells), white light had the lowest PC concentration (0.72 nmol 10 -8 cells) [42].…”

Engineered ketocarotenoid biosynthesis in the polyextremophilic red microalgaCyanidioschyzon merolae10D

“…As these pigments are absent in C. merolae , it is an interesting species with a simplified carotenoid substrate and biosynthesis enzymatic landscape in which to attempt carotenoid metabolic engineering. C. merolae also uses phycocyanin as a light harvesting pigment (Lang et al, 2020; Parys et al, 2021), a different photosystem structure than in green algae and higher plants, opening the question what effects carotenoid modifications would have in this system.…”