Photoadaptation of two members of the Chlorophyta ( Scenedesmus and Chlorella ) in laboratory and outdoor cultures: changes in chlorophyll fluorescence quenching and the xanthophyll cycle

Abstract

The role of the xanthophyll cycle in the adaptation of two chlorococcal algae Scenedesmus quadricauda and Chlorella sorokiniana to high irradiance was studied under laboratory and outdoor conditions. We wished to elucidate whether the xanthophyll cycle plays a key role in dissipating the excesses of absorbed light, as in higher plants, and to characterise the relationship between chlorophyll fluorescence parameters and the content of xanthophyll-cycle pigments. The xanthophyll cycle was found to be operative in both species; however, its contribution to overall non-photochemical quenching (NPQ) could only be distinguished in Scenedesmus (15-20% of total NPQ). The Scenedesmus cultures showed a larger pool of xanthophyll-cycle pigments than Chlorella, and lower sensitivity to photoinhibition as judged from the reduction of maximum quantum yield of photosystem II. In general, both algae had a larger xanthophyll-cycle pool when grown outdoors than in laboratory cultures. Comparing the two species, Scenedesmus exhibited a higher capacity to adapt to high irradiance, due to an effective quenching mechanism and high photosynthetic capacity; in contrast, Chlorella represents a species with a larger antennae system, less-efficient quenching and lower photosynthetic performance. Non-photochemical quenching (NPQ) induced through the xanthophyll cycle can, to a limited extent, represent a regulatory factor in diluted algal cultures grown in outdoor solar photobioreactors, as well as in natural algal phytoplankton populations exposed transiently to high irradiance. However, it does not play an appreciable role in dense, well-mixed microalgal suspensions.

Use of in vivo chlorophyll fluorescence to estimate photosynthetic activity and biomass productivity in microalgae grown in different culture systems

“…These devices present different characteristics according to the quality of actinic lamps (halogen, red or blue light emitted diodes), sensitivity and measuring units (cuvettes versus fiber). On the other hand, measurements of in vivo chlorophyll fluorescence in algal mass cultures in open or closed photobioreactors are still scarce (Vonshack et al, 1994;Torzillo et al, 1996;Masojídek et al, 1999Masojídek et al, , 2011Kromkamp et al, 2009).…”

Photon irradiance required to support optimal growth and interrelations between irradiance and pigment composition in the green algaHaematococcus pluvialis

“…However, the role of the xanthophyll cycle in microalgae is ambiguous, since its contribution to energy dissipation can vary significantly among species (Niyogi et al, 1997;Casper-Lindley & Bjo¨rkman, 1998;Masojidek et al, 1999;Masojidek et al, 2004). In this study, a distinct synthesis of zeaxanthin was observed in Haematococcus pluvialis cultures exposed to 400 mmol m À2 s…”

The Xanthophyll Cycle in Aquatic Phototrophs and Its Role in the Mitigation of Photoinhibition and Photodynamic Damage

“…A linear relationship between zeaxanthin formation and NPQ has also been frequently observed in higher plants (Demmig-Adams & Adams, 1996). On the other hand, a number of reports show poor correlation between the lightinduced zeaxanthin accumulation and the quenching of variable chlorophyll fluorescence in higher plants (Lichtenthaler et al, 1992;Schindler & Lichtenthaler, 1994;Schindler & Lichtenthaler, 1996), as well as in green algae (Masojidek et al, 1999). Poor correlation has been also found in green algae Dunaliella, which has similar light-harvesting and xanthophyll-cycle pigments to that of higher plants (Casper-Lindley & Bjorkman, 1998).…”