Inorganic carbon acquisition by chrysophytes

Maberly, Stephen C.; Ball, Lucy A.; Raven, John A.; Sultemeyer, Dieter. 2009 Inorganic carbon acquisition by chrysophytes. Journal of Phycology, 45 (5). 1052-1061.

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Twelve species, representing twelve families of the chrysophytes sensu lato, were tested for their ability to take up inorganic carbon. Using the pH-drift technique, CO2 compensation points generally varied between 1 and 20 µmol•L-1 with a mean concentration of 5 µmol•L-1. Neither pH nor alkalinity affected the CO2 compensation point. The concentration of oxygen had a relatively minor effect on CO2 uptake kinetics and the mean CO2 compensation point calculated from the kinetic curves was 3.6 µmol•L-1 at 10-15 kPa starting oxygen partial pressure and 3.8 µmol•L-1 at atmospheric starting oxygen partial pressure (21 kPa). Similarly, uptake kinetics were not affected by alkalinity, and hence concentration of bicarbonate. Membrane inlet mass spectrometry (MIMS) in the presence and absence of acetozolamide suggested that external carbonic anhydrase in Dinobryon sertularia and Synura petersenii was either very low, absent. Rates of net HCO3- uptake were very low (around 5% of oxygen evolution) using MIMS and decreased rather than increased with increasing HCO3- concentration suggesting that it was not a real uptake. The CO2 compensation points determined by MIMS for CO2 uptake and oxygen evolution were similar to those determined in pH-drift and were above 1 µmol•L-1. Overall, the results suggest that chrysophytes as a group lack a carbon concentrating mechanism, or an ability to make use of bicarbonate as an alternative source of inorganic carbon. The possible evolutionary and ecological consequences of this are discussed.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Water > WA02 Quantifying processes that link water quality and quantity, biota and physical environment > WA02.3 Physico-chemical processes and effects on freshwater biot
UKCEH and CEH Sections/Science Areas: Parr
ISSN: 0022-3646
Additional Keywords: carbon dioxide, carbon-concentrating mechanisms, freshwater algae, pH-drift, photosynthesis, pyrenoids
NORA Subject Terms: Botany
Biology and Microbiology
Date made live: 28 Oct 2009 15:55 +0 (UTC)

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