Cell morphology and metabolism[edit]
Halobacteria are single-celled, rod-shaped microorganisms that are among the most ancient forms of life and appeared on Earth billions of years ago. . The membrane consists of a single lipid bilayer surrounded by an S-layer.[2] The S-layer is made of a cell-surface glycoprotein, which accounts for approximately 50% of the cell surface proteins.[3] These proteins form a lattice in the membrane. Sulfate residues are abundant on the glycan chains of the glycoprotein, giving it a negative charge. The negative charge is believed to stabilize the lattice in high-salt conditions.[4]
Amino acids are the main source of chemical energy for H. salinarum, particularly arginine and aspartate, though they are able to metabolize other amino acids, as well.[2] H. salinarum have been reported to not be able to grow on sugars, and therefore need to encode enzymes capable of performing gluconeogenesis to create sugars. Although "H. salinarum" is unable to catabolize glucose, the transcription factor TrmB has been proven to regulate the gluconeogenic production of sugars found on the S-layer glycoprotein.