The variability of light-harvesting complexes in aerobic anoxygenic phototrophs.
Light-harvesting capacity was investigated in six species of aerobic anoxygenic phototrophic (AAP) bacteria using absorption spectroscopy, fluorescence emission spectroscopy, and pigment analyses. Aerobically grown AAP cells contained approx. 140-1800 photosynthetic reaction centers per cell, an order of magnitude less than purple non-sulfur bacteria grown semiaerobically. Three of the studied AAP species did not contain outer light-harvesting complexes, and the size of their reaction center core complexes (RC-LH1 core complexes) varied between 29 and 36 bacteriochlorophyll molecules. In AAP species containing accessory antennae, the size was frequently reduced, providing between 5 and 60 additional bacteriochlorophyll molecules. In Roseobacter litoralis, it was found that cells grown at a higher light intensity contained more reaction centers per cell, while the size of the light-harvesting complexes was reduced. The presented results document that AAP species have both the reduced number and size of light-harvesting complexes which is consistent with the auxiliary role of phototrophy in this bacterial group.
Center Algatech, Institute of Microbiology CAS, 37981, Třeboň, Czech Republic. selyaninvv@gmail.com.
Vadim
V
Selyanin
Center Algatech, Institute of Microbiology CAS, 37981, Třeboň, Czech Republic.
Dzmitry
D
Hauruseu
Center Algatech, Institute of Microbiology CAS, 37981, Třeboň, Czech Republic.
Michal
M
Koblížek
D000332:Aerobiosis; D020561:Alphaproteobacteria / Q000737:chemistry / Q000378:metabolism*; D001429:Bacteriochlorophylls / Q000378:metabolism; D020563:Gammaproteobacteria / Q000737:chemistry / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000378:metabolism; D052817:Phototrophic Processes
D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins
Bacterial photosynthesis; Bacteriochlorophyll; Photosynthetic unit size; Purple non-sulfur bacteria; Reaction center core complex