Variations in the Lipid Composition of Aerobic, Halophilic Archaeobacteria

Abstract

Members of the alkaliphilic genera Natronobacterium and Natronococcus have been shown to be capable of synthesising at least two different diether lipids. It has been possible to show, not only that the relative amounts of the two diethers vary in different strains, but that their relative composition is influenced by the growth conditions. Initial studies indicated that salinity plays a role in determining the relative distribution of the diethers in the haloalkaliphiles tested. However, it has been possible to show that other factors, such as growth phase play a significant role.

All members of the family Halobacteriaceae contain MK-8 and MK-8(VIII-H₂) in varying amounts. Using representatives of the various taxonomic groupings it has been possible to show that growth conditions reproducibly affect the relative amounts of these two lipoquinones. Present investigations have not been able to fully account for the factors responsible for these changes, although there seems to be a correlation between growth phase and growth rate. The extent of the changes appears to have some significance in the chemotaxonomy of this group of organisms.