Ubiquinone, Fatty acid and DNA Base Composition Determination as a Guide to the Taxonomy of the Genus Thiobacillus

Abstract

Facultatively chemolithotrophic thiobacilli. Thiobacillus perometabolis thi 022, Thiobacillus sp. A2, Thiobacillus novellus, Thiobacillus organoparus and Thiobacillus acidophilus, had ubiquinones with 10 isoprene units (Q-10) (group I). These species also had [octadecenoic acid (18:1) + cyclopropane acid of C19 (19cyc)] as major non-hydroxylated fatty acids. The organisms, except T. novellus, contained 3-hydroxydecanoic acid (3-OH 10:0) or 3-hydroxytetradecanoic acid (3-OH 14:0) as hydroxy fatty acids. DNA base compositions of these species were 63 to 68 mol% G + C. Other facultatively chemolithotrophic thiobacilli, including T. perometabolis thi 023, Thiobacillus delicatus and Thiobacillus intermedius contained Q-8 (group II). They had hexadecanoic acid (16:0), [hexadecenoic acid (16:1) + cyclopropane acid of C17 (17cyc)] and [18:1 + 19cyc] as major non-hydroxylated fatty acids. The species of group II had 3-OH 10:0 and some possessed 3-hydroxydodecanoic acid (3-OH 12:0). The DNA base composition of these strains was about 65 mol% G + C. Obligate chemolithotrophic thiobacilli contained Q-8 (group III). They had 16:0, [16:1 + 17cyc] with or without [18:1 + 19cyc] as major non-hydroxylated fatty acids. The species of group III contained 3-OH 12:0 and some had 3-OH 10:0 when grown at neutral pH and 3-OH 14:0 in acidophilic conditions. DNA base compositions of these organisms ranged from 51 to 64 mol% G + C. Chemotaxonomic characteristics would seem to be useful for the identification and the classification of thiobacilli.