Physiology and Molecular-Genetics of 'Thermus' and 'Bacillus'. 6. TemperatureInduced Alterations in the Fatty Acid Composition of Wild Type and Plasmid-Cured 'Thermus' Strains

摘要

The effect of temperature on the fatty acid content and composition of five wildtype and five plasmid-cured strains of Thermus was examined. The fatty acid content of wild type strains was higher than in plasmid-cured strains ranging between 2.9-4.4%, in the temperature range of 40-80 C. On the other hand, plasmid-cured strains, which were capable of growth at 35 C, but not above 70 C had a lower fatty acid content, which increased with temperature from 1.1 to 2.8%. The ability of plasmid-cured strains to grow at 35 C was associated with a high proportion of iso C16:0, iso C15:0, anteiso C17:0 and anteiso C17:1, with smaller contributions of iso C17:0 and anteiso C15:0. However, growth of wild type strains at 75 and 80 C was associated with iso C17:0 levels in excess of 45.6% coupled with a lower contribution by iso C15:0. Plasmid-cured strains only reached a maximum of 30.2% of iso C17:0. The study suggests that the membrane of wild type strains consisted of fatty acids with high melting points, and allowed growth at temperatures above 70 C, whereas the plasmid-cured strains, due to a shift to shorter chain fatty acids and unsaturation showed a lowering of the growth temperature range.