ACCLIMATION TO LOW TEMPERATURE OF TWO ARTHROSPIRA PLATENSIS (CYANOBACTERIA) STRAINS INVOLVES DOWN‐REGULATION OF PSII AND IMPROVED RESISTANCE TO PHOTOINHIBITION¹

Abstract

This study aimed to compare the ability of two Arthrospira platensis (Nordst.) Gomont strains, M2 and Kenya, isolated from two different habitats, to acclimate to low temperature (15°C). Both strains had similar growth rates at 30°C, but once acclimated to low temperature, M2 showed a greater decline in growth (59% vs. 41% in the Kenya strain). We suggest that the Kenya strain acclimated better to low temperature by down-regulating its photosynthetic activity through (i) decreasing antenna size and thus reducing energy flux into the photosystems; (ii) decreasing reaction center density (RC/CSX ) and the performance index, thus decreasing the trapping probability and electron transport rate while maintaining electron transport probability for electron transport beyond QA (-) unchanged; (iii) increasing the energy dissipation flux. In contrast, the M2 strain showed no difference in antenna size and exhibited a much lower decrease in RC/CSX and a lower dissipation rate. Hence, the Kenya strain minimized potential damage on the acceptor side of PSII compared to the M2 cells. Furthermore, acclimation to low temperature was accompanied by an improved mechanism for handling excess energy resulting in an enhanced ability of the Kenya strain to rapidly repair damaged PSII RCs and withstand a high photon flux density (HPFD) stress; this finding might be defined as a cross-adaptation phenomenon. This study may provide a tool to identify strains suitable for outdoor mass-production in different regions characterized by different climate conditions.

Algal communities of Kenyan soda lakes with a special focus on Arthrospira fusiformis

“…This has been proven also in laboratory experiments for some environmental factors such as irradiance (wu et al 2005;helBing et al 2006helBing et al ), temperature (gao et al 2008VonShaK & noVoplanSKy 2008) salinity (KeBeDe 1997) and alkaliphilic conditions (VonShaK & TomaSelli 2000). In our survey, its growth seemed however to be restricted to pH levels < 10.3.…”

iTRAQ-Based Quantitative Proteomic Analysis of Spirulina platensis in Response to Low Temperature Stress

“…Lee-Feng et al [18] demonstrated that enhanced antioxidant enzyme activities at LT (15°C) are an efficient regulatory strategic response to LT-induced photoinhibition. In addition, a previous study also indicated that the adaptation of Arthrospira platensis to cold stress involves a down-regulation of photosynthetic activity and increased resistance to photoinhibition [19]. …”

Ecomorphological variability of Arthrospira fusiformis (Cyanoprokaryota) in African soda lakes

“…), temperature (Gao et al. ; Vonshak and Novoplansky ), and salinity (Kebede ). So far, no extensive field studies exist that indicate whether these changes that have been observed under extreme laboratory situations also occur in nature.…”

“…The diverse ecological strategies adopted by phytoplankton can be related to their morphological variability (Reynolds 1997); this acclimation value is directed toward adapting the best fitting trait to the prevailing environmental template (Naselli-Flores et al 2007). Morphological modification of A. fusiformis has been well studied under laboratory conditions such as variable irradiance (Wu et al 2005;Helbling et al 2006), temperature (Gao et al 2008;Vonshak and Novoplansky 2008), and salinity (Kebede 1997). So far, no extensive field studies exist that indicate whether these changes that have been observed under extreme laboratory situations also occur in nature.…”