Halothermothrix orenii H 168

Halothermothrix_orenii
Names Halothermothrix orenii H 168
Accession numbers NC_011899
Background Halothermothrix orenii (strain H 168 / OCM 544 / DSM 9562) is a Gram-negative thermohalophilic, anaerobic bacterium isolated from sediment of a Tunisian salt lake. It grows optimally at 60 degrees Celsius (maximum of 70 degrees Celsius) with 10% NaCl (NaCl growth range between 4 - 20%). H.orenii is the first Gram-negative representative of the phylum Firmicutes and the first thermohalophilic organism with a complete genome sequence. The analysis of its genome reveals a mixture of both Gram-positive and Gram-negative properties such as the presence of both a sporulating system typical of Firmicutes and a characteristic Gram-negative pathway for lipid A biosynthesis. Adaptation to high temperatures is mainly correlated to the production of more stable proteins. This can be achieved by a reduced frequency of the thermolabile amino acids histidine, glutamine and threonine and an increased number of both positively charged and negatively charged residues which suggest that ionic bonds between oppositely charged residues may help to stabilize protein structure at high temperatures. In general, two major adaptation strategies to high salinity are observed in halophilic organisms. Salt-in strategy involves a shift in amino acid composition, with an increased number of negatively charged residues located on the surface of the enzymes, coupled to the uptake of K+ and Cl2 and the extrusion of cytotoxic Na+ resulting in a cytoplasmic ion composition substantially different from the surroundings. The salt-out strategy involves the production of large amounts of specific organic osmolytes (compatible solutes) which can be accumulated to high concentrations without disturbing cellular functions. The salt-out strategy is commonly found among organisms that live in environments of moderate salinity or of high salt fluctuations. Genome tag analysis indicated that H. orenii does not contain high proportions of negatively charged acidic amino acids necessary for a salt-in survival strategy. The amino acid composition of the proteins in H.orenii resembles the profile of thermophilic organisms and is quite distinct from that of the salt-in halophilic profiles, suggesting that its proteins have been adapted to high temperatures and to a salt-out strategy. It is possible that sucrose acts as a compatible solute allowing H.orenii to maintain an osmotic balance of the cell cytoplasm with the outside environment. H. orenii is of interest because it survives hot, salty, anaerobic environments and produces thermohalophilic enzymes for biotechnology. It is also a high hydrogen producer and is used in bioremediation of hot salty oil fields. (adapted from PMID: 19145256). (EBI Integr8)
Taxonomy
Kingdom:Bacteria
Phylum:Firmicutes
Class:Clostridia
Order:Halanaerobiales
Family:Halanaerobiaceae
Genus:Halothermothrix
Species:orenii
Strain H 168
Complete Yes
Sequencing centre (03-JUN-2008) US DOE Joint Genome Institute, 2800 Mitchell Drive B100, Walnut Creek, CA 94598-1698, USA
(14-JAN-2009) National Center for Biotechnology Information, NIH, Bethesda, MD 20894, USA
Sequencing quality Level 6: Finished
Sequencing depth NA
Sequencing method Sanger, 454
Isolation site Salted lake sediment
Isolation country NA
Number of replicons 1
Gram staining properties Negative
Shape Bacilli
Mobility Yes
Flagellar presence Yes
Number of membranes 2
Oxygen requirements Anaerobic
Optimal temperature 60.0
Temperature range Thermophilic
Habitat Aquatic
Biotic relationship Free living
Host name NA
Cell arrangement Singles
Sporulation NA
Metabolism NA
Energy source NA
Diseases NA
Pathogenicity No