Effect of growth temperature on fatty acid composition of ten thermus strains.

The fatty acid composition of Thermus spp., including T. aquaticus ATCC 25104, T. thermophilus DSM 579, T. flavus DSM 674, and seven wild strains was examined. Organisms were tested at a minimum of either 35, 40, or 45 degrees C and at an optimum of 60 or 70 degrees C. Total fatty acid content per dry weight of cells varied between 1.2 and 3.7%, and the quantity of fatty acids was higher at the high temperature range in the majority of strains. At the optimum temperature, strains could be assigned to three chemotaxonomic groups with reference to the ratio of iso C(15:0)/iso C(17:0). In six of the strains the ratio of iso C(15:0)/iso C(17:0) remained unchanged at the minimum temperature, whereas in four strains the ratio was reversed. The proportion of the C(15:0) and C(17:0) isobranched acids was decreased and the proportion of anteisobranched fatty acids, namely anteiso C(15:0), anteiso C(17:0), and anteiso C(17:1), was increased at the lower temperature range. Some changes were seen in the levels of the n-C(16:0) and iso C(16:0) acids, but these were strain specific.