obsolete 1-hydro-1,1a-dihydroxy-9-fluorenone dehydrogenase activity (obsolete GO:0034787)
OBSOLETE. Catalysis of the reaction: 1-hydro-1,1a-dihydroxy-9-fluorenone + H2O = 2,3-dihydroxy-2'-carboxybiphenyl + 3 H+ + 2 e-.