Rhodocyclaceae

• Rhodocyclus species can grow photoheterotrophically or photoautotrophically under anoxia or heterotrophically on fatty acids under air. Dominant respiratory quinone is. Cells are curved rods or rings.
• Propionivibrio species grow anaerobically by fermentation of hydrocarbons, yielding fatty acids, specifically propionate. The dominant respiratory quinone is ubiquinone-8. Cells are curved rods.
• Azospira species are heterotrophs that can fix molecular nitrogen as their source of nitrogen for growth. Cells are spirillae or curved rods. The dominant respiratory quinone is ubiquinone-8.