CO₂ assimilation in the chemocline of Lake Cadagno is dominated by a few types of phototrophic purple sulfur bacteria

TY - JOUR

T1 - CO2 assimilation in the chemocline of Lake Cadagno is dominated by a few types of phototrophic purple sulfur bacteria

AU - Storelli, Nicola

AU - Peduzzi, Sandro

AU - Saad, Maged

AU - Frigaard, Niels-Ulrik

AU - Perret, Xavier

AU - Tonolla, Mauro

PY - 2013/5

Y1 - 2013/5

N2 - 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 in situ for their ability to fix CO2. The purple sulfur bacterium Candidatus 'Thiodictyon syntrophicum' strain Cad16T had the highest CO2 assimilation rate in the light of the four strains tested and had a high CO2 assimilation rate even in the dark. The CO2 assimilation of the population represented by strain Cad16T was estimated to be up to 25% of the total primary production in the chemocline. Pure cultures of strain Cad16T exposed to cycles of 12 h of light and 12 h of darkness exhibited the highest CO2 assimilation during the first 4 h of light. The draft genome sequence of Cad16T showed the presence of cbbL and cbbM genes, which encode form I and form II of RuBisCO, respectively. Transcription analyses confirmed that, whereas cbbM remained poorly expressed throughout light and dark exposure, cbbL expression varied during the light-dark cycle and was affected by the available carbon sources. Interestingly, the peaks in cbbL expression did not correlate with the peaks in CO2 assimilation.

AB - 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 in situ for their ability to fix CO2. The purple sulfur bacterium Candidatus 'Thiodictyon syntrophicum' strain Cad16T had the highest CO2 assimilation rate in the light of the four strains tested and had a high CO2 assimilation rate even in the dark. The CO2 assimilation of the population represented by strain Cad16T was estimated to be up to 25% of the total primary production in the chemocline. Pure cultures of strain Cad16T exposed to cycles of 12 h of light and 12 h of darkness exhibited the highest CO2 assimilation during the first 4 h of light. The draft genome sequence of Cad16T showed the presence of cbbL and cbbM genes, which encode form I and form II of RuBisCO, respectively. Transcription analyses confirmed that, whereas cbbM remained poorly expressed throughout light and dark exposure, cbbL expression varied during the light-dark cycle and was affected by the available carbon sources. Interestingly, the peaks in cbbL expression did not correlate with the peaks in CO2 assimilation.

U2 - 10.1111/1574-6941.12074

DO - 10.1111/1574-6941.12074

M3 - Journal article

C2 - 23330958

SN - 0168-6496

VL - 84

SP - 421

EP - 432

JO - F E M S Microbiology Ecology

JF - F E M S Microbiology Ecology

IS - 2

ER -