This is a lousy way to make a living, so to speak. Fumarate, DMSO, TMAO E. coli and other bacteria can use some organic compounds as electron acceptors under anaerobic conditions. Fumarate is less favorable than nitrate as an acceptor, and NO 3 - suppresses the expression of the genes for fumarate reductase. ATP synthesis by substrate-level phosphorylation only. See handout for various products made during fermentations.
Light can provide energy by two fundamentally different mechanisms.
Light-activated proton extrusion. Light-activated electron transport with secondary proton extrusion. The first mechanism is found in some members of the Archaea, namely the Halobacterium sp. Protein is also somewhat similar to rhodopsin of the eye. In the dark, the retinal re-isomerizes back to original configuration and bind a proton from the cytoplasmic side of the membrane.