CO2 assimilation in the chemocline of Lake Cadagno is dominated by a few types of phototrophic purple sulfur bacteria. Issue 2 (11th February 2013)

• Record Type: Journal Article
• Authors: Storelli, Nicola; Peduzzi, Sandro; Saad, Maged M.; Frigaard, Niels‐Ulrik; Perret, Xavier; Tonolla, Mauro
• Is Part Of: FEMS microbiology ecology. Volume 84:Issue 2(2013)
• Page Start: 421
• Page End: 432
• Publication Date: 2013-02-11
• Subjects: Microbial ecology -- Periodicals; Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1574-6941.12074
• Languages: English
• ISSNs: 0168-6496

Abstract

<abstract abstract-type="main" id="fem12074-abs-0001"> <title>Abstract</title> <p>Lake Cadagno is characterized by a compact chemocline that harbors high concentrations of various phototrophic sulfur bacteria. Four strains representing the numerically most abundant populations in the chemocline were tested in dialysis bags <italic>in situ</italic> for their ability to fix CO<sub>2</sub>. The purple sulfur bacterium <italic>Candidatus</italic> 'Thiodictyon syntrophicum' strain Cad16<sup>T</sup> had the highest CO<sub>2</sub> assimilation rate in the light of the four strains tested and had a high CO<sub>2</sub> assimilation rate even in the dark. The CO<sub>2</sub> assimilation of the population represented by strain Cad16<sup>T</sup> was estimated to be up to 25% of the total primary production in the chemocline. Pure cultures of strain Cad16<sup>T</sup> exposed to cycles of 12 h of light and 12 h of darkness exhibited the highest CO<sub>2</sub> assimilation during the first 4 h of light. The draft genome sequence of Cad16<sup>T</sup> showed the presence of <italic>cbbL</italic> and <italic>cbbM</italic> genes, which encode form I and form II of RuBisCO, respectively. Transcription analyses confirmed that, whereas <italic>cbbM</italic> remained poorly expressed throughout light and dark exposure, <italic>cbbL</italic> expression varied during the light–dark cycle and was affected by the available carbon sources. Interestingly, the peaks in <italic>cbbL</italic> expression did not correlate with the peaks in CO<sub>2</sub> assimilation.</p> </abstract>