Catalyzes the asymmetrical introduction of one keto group at the C-2 position of spheroidene and two keto groups at the C-2 and C-2' positions of spirilloxanthin. 4 H(+) + 2 O2 + 4 reduced [2Fe-2S]-[ferredoxin] + spheroidene = 3 H2O + 4 oxidized [2Fe-2S]-[ferredoxin] + spheroiden-2-one 4 H(+) + 2 O2 + 4 reduced [2Fe-2S]-[ferredoxin] + spirilloxanthin = 2-oxospirilloxanthin + 3 H2O + 4 oxidized [2Fe-2S]-[ferredoxin] 2-oxospirilloxanthin + 4 H(+) + 2 O2 + 4 reduced [2Fe-2S]-[ferredoxin] = 2,2'-dioxospirilloxanthin + 3 H2O + 4 oxidized [2Fe-2S]-[ferredoxin] Binds 1 heme per subunit. Carotenoid biosynthesis; spheroidene biosynthesis.