Effect of Growth Temperature on the Lipid Composition of two Strains of Thermus sp.

Abstract

Growth-temperature-dependent alterations in the total extractable lipid and polar lipid components of two strains of Thermus sp. isolated from a Portuguese hot spring were studied between 50°C and 78°C. The total extractable lipid varied between 8·0 and 10·6% of the cell dry weight; there were no alterations in the phosphorus and carotenoid content of the lipid extract, but the carbohydrate content increased as the growth temperature was raised. Three glycolipids and the four phospholipids were separated by thin-layer chromatography. The relative concentration of the major glycolipid (GL1) of strain SPS 17 (yellow-pigmented) increased with the growth temperature, whereas the relative concentration of a minor glycolipid (GL2) decreased. There were no temperature-dependent alterations in the relative concentrations of GL1 and GL2 from strain SPS 11 (colourless). The proportion of the major phospholipid (PL2) decreased in both strains as the growth temperature increased, whereas that of a minor phospholipid (PL1) increased. The major fatty acyl chains of both strains were 13-methyltetradecanoate (iso-C15) and 15-methylhexadecanoate (iso-C17). The GL1 in strains SPS 11 and SPS 17 had a glucose:glucosamine:glycerol:long fatty acyl chain ratio of 3:1:1:3. † Present address: Departamento de Bioquimica, Facultad de Ciencias, Universidad del Pais Vasco, 48080 Bilbao, Spain.