ABSTRACT
Purple phototrophs are the most metabolically versatile organisms on Earth and display a huge diversity of energy modes and metabolic capabilities (Hunter et al. 2009). They can dispense with photosynthesis and grow as heterotrophs in the dark; they can use organic acids, amino acids, fatty acids, alcohols, carbohydrates, C1, or aromatic compounds; they can ferment or perform anaerobic respiration; and they can fix nitrogen and CO2 and produce hydrogen. Purple phototrophs have been invaluable models for investigating the assembly, structure, and function of photosynthetic membranes because of their amenability to genetic manipulation; the level of biochemical, structural, and spectroscopic characterization; and the relative simplicity of their assembly pathways and photosynthetic apparatus. This chapter will focus on the most heavily studied purple phototroph, Rhodobacter sphaeroides.
