Expression and functioning of retinal-based proton pumps in a saltern crystallizer brine.
We examined the presence of bacteriorhodopsin and other retinal protein pigments in the microbial community of the saltern crystallizer ponds in Eilat, Israel, and assessed the effect of the retinal-based proton pumps on the metabolic activity. The biota of the hypersaline (~309 g salts l(-1)) brine consisted of ~2200 β-carotene-rich Dunaliella cells and ~3.5 × 10(7) prokaryotes ml(-1), most of which were flat, square or rectangular Haloquadratum-like archaea. No indications were obtained for massive presence of Salinibacter. We estimated a concentration of bacteriorhodopsin and bacteriorhodopsin-like pigments of 3.6 nmol l(-1). When illuminated, the community respiration activity of the brine samples in which oxygenic photosynthesis was inhibited by 3-(3-4-dichlorophenyl)-1,1-dimethylurea, decreased by 40-43 %. This effect was interpreted to be the result of competition between two energy yielding systems: the bacteriorhodopsin proton pump and the respiratory chain. The results presented have important implications for the interpretation of many published data on photosynthetic and respiratory activities in hypersaline environments.
Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, Jerusalem, 91904, Israel. aharon.oren@mail.huji.ac.il.
Aharon
A
Oren
The Mina and Everard Goodman Faculty of Life Sciences, and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 529002, Israel.
Said
S
Abu-Ghosh
Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, 69978, Israel.
Tal
T
Argov
The Faculty of Dental Medicine, Bio-Medical Sciences in Dental Medicine, The Hebrew University, Hadassah School of Dental Medicine, Jerusalem, 91120, Israel.
Eliahu
E
Kara-Ivanov
Faculty of Biology, Technion, Israel Institute of Technology, Technion City, Haifa, 32000, Israel.
Dror
D
Shitrit
Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel.
Adi
A
Volpert
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 529002, Israel.|The Interuniversity Institute for Marine Sciences in Eilat, Eilat, 88103, Israel.
Rael
R
Horwitz
D001105:Archaea / Q000378:metabolism*; D001436:Bacteriorhodopsins / Q000378:metabolism*; D000460:Chlorophyta / Q000378:metabolism*; D004579:Electron Transport; D064307:Microbiota; D010788:Photosynthesis; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*
D001436:Bacteriorhodopsins
Bacteriorhodopsin; Community respiration; Haloquadratum; Hypersaline; Retinal; Saltern