Vljudno vabljeni na predavanje prof. Aharona Orena (Department of Plant and Environmental Sciences, The Institute of Life Sciences, The Hebrew University of Jerusalem, Israel), ki bo v četrtek 13.2.2014 ob 15h v B1 (Biološko središče, Večna pot 111, Ljubljana).
Naslov predavanja: Red, extremely halophilic, but not archaeal: The biology of Salinibacter ruber.
Povzetek: Red halophilic Archaea of the family Halobacteriaceae dominate the prokaryote communities of saltern crystallizer ponds world-wide. However, culture-independent studies based on sequencing of environmental 16S rRNA sequences made it clear that an organism phylogenetically affiliated with the Bacteroidetes branch of the bacterial domain is quantitatively important in the same ecosystems. The organism was isolated and was described in 2002 as Salinibacter ruber. Salinibacter grows between 20 and 30% salt, and is unable to grow below a salinity of 15%. Its red pigment (salinixanthin) was identified as a novel acylated C40-carotenoid glycoside. A retinal proton pump (xanthorhodopsin) is present as well, and salinixanthin acts as a light antenna for the retinal protein. The membrane contains unique sulfonolipids. Although belonging to the bacterial domain, Salinibacter shares many characteristic properties with the extremely halophilic Archaea such as a high requirement for chloride for growth, accumulation of KCl to provide osmotic balance, the possession of a large excess of acidic amino acids in its cellular proteins, and the virtual absence of organic osmotic solutes. Many of the enzymes tested depend on high salt concentrations for activity. Comparison of the Salinibacter genome with the genomes of the halophilic Archaea shows how two groups of phylogenetically unrelated organisms maintain a similar life style and are adapted to life in salt-saturated brines.
(organizira prof. dr. Nina Gunde – Cimerman)
