We discovered natural photosynthesis using Zn-containing bacteriochlorophyll a in an acidophilic bacterium Acidiphilium rubrum. Chemical analysis of the cell extracts gave a 13:2:1 molar ratio of Zn-bacteriochlorophyll a: Mg-bacteriochlorophyll a: bacteriopheophytin a. Most of the pigments are associated with fully active reaction center and light-harvesting complexes analogous to those in purple photosynthetic bacteria. The finding indicates an unexpectedly wide variability of photosynthesis.