Effects of long-term ionic and osmotic stress conditions on photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803

2005 ◽  
Vol 32 (9) ◽  
pp. 807 ◽  
Author(s):  
Saowarath Jantaro ◽  
Paula Mulo ◽  
Tove Jansén ◽  
Aran Incharoensakdi ◽  
Pirkko Mäenpää

Salinity is considered to be one of the most severe problems in worldwide agricultural production, but the published investigations give contradictory results of the effect of ionic and osmotic stresses on photosynthesis. In the present study, long-term effects of both ionic and osmotic stresses, especially on photosynthesis, were investigated using the moderately halotolerant cyanobacterium Synechocystis sp. PCC 6803. Our results show that the PSII activity and the photosynthetic capacity tolerated NaCl but a high concentration of sorbitol completely inhibited both activities. In line with these results, we show that the amount of the D1 protein of PSII was decreased under severe osmotic stress, whereas the levels of PsaA / B and NdhF3 proteins remained unchanged. However, high concentrations of sorbitol stress led to a drastic decrease of both psbA (encoding D1) and psaA (encoding PsaA) transcripts, suggesting that severe osmotic stress may abolish the tight coordination of transcription and translation normally present in bacteria, at least in the case of the psaA gene. Taken together, our results indicate that the osmotic stress component is more detrimental to photosynthesis than the ionic one and, furthermore, under osmotic stress, the D1 protein appears to be the target of this stress treatment.

Life ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1300
Author(s):  
Francesca Marchetto ◽  
Marco Roverso ◽  
Davide Righetti ◽  
Sara Bogialli ◽  
Francesco Filippini ◽  
...  

One of the main concerns in industrialized countries is represented by per- and poly-fluoroalkyl substances (PFAS), persistent contaminants hardly to be dealt with by conventional wastewater treatment processes. Phyco-remediation was proposed as a green alternative method to treat wastewater. Synechocystis sp. PCC6803 is a unicellular photosynthetic organism candidate for bioremediation approaches based on synthetic biology, as it is able to survive in a wide range of polluted waters. In this work, we assessed the possibility of applying Synechocystis in PFAS-enriched waters, which was never reported in the previous literature. Respirometry was applied to evaluate short-term toxicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which did not affect growth up to 0.5 and 4 mg L−1, respectively. Continuous and batch systems were used to assess the long-term effects, and no toxicity was highlighted for both compounds at quite high concentration (1 mg L−1). A partial removal was observed for PFOS and PFOA, (88% and 37%, with removal rates of about 0.15 and 0.36 mg L−1 d−1, respectively). Measurements in fractionated biomass suggested a role for Synechocystis in the sequestration of PFAS: PFOS is mainly internalized in the cell, while PFOA is somehow transformed by still unknown pathways. A preliminary bioinformatic search gave hints on transporters and enzymes possibly involved in such sequestration/transformation processes, opening the route to metabolic engineering in the perspective application of this cyanobacterium as a new phyco-remediation tool, based on synthetic biology.


2002 ◽  
Vol 46 (4) ◽  
pp. 905-915 ◽  
Author(s):  
Koji Mikami ◽  
Yu Kanesaki ◽  
Iwane Suzuki ◽  
Norio Murata

2012 ◽  
Vol 194 (24) ◽  
pp. 6828-6836 ◽  
Author(s):  
M. Akai ◽  
K. Onai ◽  
M. Morishita ◽  
H. Mino ◽  
T. Shijuku ◽  
...  

2001 ◽  
Vol 2001 ◽  
pp. 141-141
Author(s):  
M.O. Mohammed ◽  
P.C. Chiy ◽  
C. J. C. Phillips

The presence of high concentrations of sodium in the mammalian small intestine plays a major role in facilitating copper absorption (e.g. Wapnir and Stiel, 1987). An experiment was conducted that investigated the medium and long-term effects of adding sodium to the diet of sheep on the copper accumulation in body tissues.


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