Ubiquinones (Coenzyme Q) in hydrogen oxidizing bacteria

Area of Science:

• Microbiology
• Biochemistry
• Bacterial Physiology

Background:

• Hydrogen-oxidizing bacteria are crucial for biogeochemical cycles.
• Understanding their metabolic pathways requires knowledge of their electron transport components.
• Isoprenoid quinones are vital components of bacterial electron transport chains.

Purpose of the Study:

• To investigate the isoprenoid quinone content and composition.
• To analyze quinone profiles in various hydrogen-oxidizing bacterial strains.
• To identify ubiquinone (UQ) and menaquinone presence and variations.

Main Methods:

• Bacterial cultivation and isolation.
• Extraction and purification of isoprenoid quinones.
• High-performance liquid chromatography (HPLC) for quinone analysis.
• Mass spectrometry for structural identification.

Main Results:

• All studied strains contained ubiquinone (UQ) at concentrations of 0.7–2.8 μmol/g dry weight.
• No menaquinones were detected in any of the analyzed strains.
• UQ-10 was the predominant ubiquinone, found in all strains except one.
• UQ-8 was additionally present in two strains.
• UQ-9 was exclusively identified in Pseudomonas carboxydohydrogena.

Conclusions:

• Hydrogen-oxidizing bacteria predominantly utilize ubiquinone, particularly UQ-10, for their electron transport systems.
• The absence of menaquinones suggests specific respiratory adaptations in these bacteria.
• Variations in UQ side-chain lengths (UQ-8, UQ-9, UQ-10) may reflect distinct physiological roles or evolutionary pathways.