Converts chlorophylls (Chl) into bacteriochlorophylls (BChl) by reducing ring B of the tetrapyrrole. 3-deacetyl-3-vinylbacteriochlorophyllide a + ADP + 2 oxidized [2Fe-2S]-[ferredoxin] + phosphate = ATP + chlorophyllide a + H(+) + H2O + 2 reduced [2Fe-2S]-[ferredoxin] ADP + bacteriochlorophyllide a + 2 oxidized [2Fe-2S]-[ferredoxin] + phosphate = 3-acetyl-3-devinylchlorophyllide a + ATP + H(+) + H2O + 2 reduced [2Fe-2S]-[ferredoxin] 3-deacetyl-3-(1-hydroxyethyl)bacteriochlorophyllide a + ADP + 2 oxidized [2Fe-2S]-[ferredoxin] + phosphate = 3-devinyl-3-(1-hydroxyethyl)chlorophyllide a + ATP + H(+) + H2O + 2 reduced [2Fe-2S]-[ferredoxin] Porphyrin-containing compound metabolism; bacteriochlorophyll biosynthesis (light-independent). Chlorophyllide reductase is composed of three subunits; BchX, BchY and BchZ. Forms a heterodimer of one BchY and one BchZ subunit. Belongs to the BchN/ChlN family.