Common Freshwater Cyanobacteria Grow in 100% CO₂

Abstract

Cyanobacteria and similar organisms produced most of the oxygen found in Earth's atmosphere, which implies that early photosynthetic organisms would have lived in an atmosphere that was rich in CO2 and poor in O2. We investigated the tolerance of several cyanobacteria to very high (>20 kPa) concentrations of atmospheric CO2. Cultures of Synechococcus PCC7942, Synechocystis PCC7942, Plectonema boryanum, and Anabaena sp. were grown in liquid culture sparged with CO2-enriched air. All four strains grew when transferred from ambient CO2 to 20 kPa partial pressure of CO2 (pCO2), but none of them tolerated direct transfer to 40 kPa pCO2. Synechococcus and Anabaena survived 101 kPa (100%) pCO2 when pressure was gradually increased by 15 kPa per day, and Plectonema actively grew under these conditions. All four strains grew in an anoxic atmosphere of 5 kPa pCO2 in N2. Strains that were sensitive to high CO2 were also sensitive to low initial pH (pH 5-6). However, low pH in itself was not sufficient to prevent growth. Although mechanisms of damage and survival are still under investigation, we have shown that modern cyanobacteria can survive under Earth's primordial conditions and that cyanobacteria-like organisms could have flourished under conditions on early Mars, which probably had an atmosphere similar to early Earth's.

Effects of elevated pCO2 on epilithic and endolithic metabolism of reef carbonates

“…their net production and dark-respiration rates did not change significantly, although a slight increase of NP was noticed. In freshwater and other marine ecosystems, it was shown that cyanobacteria can grow under elevated pCO 2 , even up to 100% CO 2 (Thomas et al, 2005) and that production of microscopic phototrophs including both cyanobacteria and microalgae increases under enhanced pCO 2 (Riebesell et al, 1993;WolfGladrow et al, 1998). Here, we hypothesize that endoliths production were at saturation under ambient pCO 2 or limited by tank nutrient concentrations.…”

Installing extra bicarbonate transporters in the cyanobacterium Synechocystis sp. PCC6803 enhances biomass production

“…2A). Although cyanobacteria are commonly considered to be tolerant to high pCO 2 , the response to increased CO 2 levels differs widely between cyanobacterial species (Miyachi et al, 2003), and S. 6803 has been shown to exhibit only moderate tolerance to high CO 2 concentrations (Thomas et al, 2005). The reason(s) for high-CO 2 toxicity in many autotrophs, including plants, algae, and cyanobacteria, is not fully understood but is likely to be due to the impairment of the rubisco enzyme and the Calvin-Benson cycle by the acidic conditions generated by high CO 2 concentrations (Miyachi et al, 2003).…”

A Permian methane seep system as a paleoenvironmental analogue for the pre-metazoan carbonate platforms

“…The presence of pyrite crystals, hydrocarbons and the absence of bioturbation in the rocks at the study site provide evidence for such conditions. Despite the scarcity of salt pseudomorphs in the sediments, the predominance of coccoidal over filamentous cyanobacteria is a good indicator of hipersalinity (Thomas et al 2005). Grazing benthos do not tolerate salinities higher than 50‰, while cyanobacterial colonies are commonly found in environments with salinities up to 80‰ (Haas et al 2006).…”