This study analyzed the isoprenoid quinone composition of 51 Gram-negative, aerobic marine bacteria using high-performance liquid chromatography (HPLC) to aid bacterial identification and taxonomy. Alteromonas and Marinomonas strains predominantly contained ubiquinone-8 (Q-8), while Deleya and marine Pseudomonas species contained ubiquinone-9 (Q-9). Notably, Shewanella species were unique among aerobic Gram-negative bacteria in containing both ubiquinones and menaquinones, with some Shewanella putrefaciens strains also containing methylmenaquinones. The quinone profiles provided clear differentiation between bacterial groups and supported taxonomic reclassifications indicated by previous molecular studies. The study demonstrates that isoprenoid quinone analysis is a rapid and effective chemotaxonomic method for distinguishing marine bacterial taxa that are difficult to differentiate using phenotypic characteristics alone.

Key findings

• Alteromonas and Marinomonas strains share identical quinone profiles with predominant Q-8, distinguishing them from other marine Gram-negative bacteria
• Shewanella species uniquely contain both ubiquinones and menaquinones among aerobic Gram-negative bacteria, with methylmenaquinones found in most S. putrefaciens strains
• Isoprenoid quinone analysis confirmed previous molecular findings and supported taxonomic reassignments of misidentified Pseudomonas strains to Alteromonas or Deleya genera
• Different DNA homology groups within Shewanella putrefaciens showed distinct quinone profiles, suggesting subspecific structure within the species