Respiratory Quinone Composition of Some Acidophilic Bacteria

Sulfolobus acidocaldarius, S. brierleyi and S. solfataricus possessed caldariellaquinone (6-(3,7,11,15,19,23-hexamethyltetracosyl)-5-methylthiobenzo-[b]-thiophen-4,7-quinone) as their major lipoquinone. Traces of two smaller analogues of caldariellaquinone (containing C 25 and C 20 side-chains) and a ‘caldariellaquinone’ containing a C 30 side-chain with a single double bond were also detected. Thermoplasma acidopbilum contained unsaturated menaquinones with seven isoprene units (MK-7) as the major isoprenoid quinone. In addition, substantial levels [ ca. 20%) of a new quinone, designated thermoplasmaquinone, were detected. Acidiphilium cryptum and some related heterotrophic, acidophilic bacteria contained ubiquinones with ten isoprene units (Q- 10) as their major respiratory quinones. Bacillus acidocaldarius possessed unsaturated menaquinones with seven isoprene units (MK-7) as the major component.