I'm confused about the difference between Photoautotrophic (purple sufur) and and photoheterotrophic (purple non sulfur) proteobacteria. I know for the first one, they use sulfur as their electron source, and CO2 (since its inorganic) as their carbon source:
CO2 + H2S -- CH2O + H2O + 2S.
But the photoheterotroph (purple nonsulfur) use a different acceptor and doesnt use CO2 from the eniornemnt. (Also does its acceptor have to be inorganic (b/c of "hetero") or does "hetero" strictly refer to the source of carbon and not electron source?

Question

I'm confused about the difference between Photoautotrophic (purple sufur) and and photoheterotrophic (purple non sulfur) proteobacteria. I know for the first one, they use sulfur as their electron source, and CO2 (since its inorganic) as their carbon source:
 CO2 + H2S --> CH2O + H2O + 2S. 
But the photoheterotroph (purple nonsulfur) use a different acceptor and doesnt use CO2 from the eniornemnt. (Also does its acceptor have to be inorganic (b/c of "hetero") or does "hetero" strictly refer to the source of carbon and not electron source?

anonymous · Answer

It strictly refers to the source of carbon.

All autotrophic organisms have CO_2 as their source of carbon, and all heterotrophic organisms have organic compounds as their source of carbon.