Catalyzes the Fe(2+) and alpha-ketoglutarate-dependent oxidation of pentalenolactone D to pentalenolactone F. Also able to catalyze the oxidation of pentalenolactone D to pentalenolactone E. In presence of neopentalenolactone D, mediates production of PL308 and possibly neopentalenolactone E. 2 2-oxoglutarate + 2 O2 + pentalenolactone D = 2 CO2 + H2O + pentalenolactone F + 2 succinate Binds 1 Fe(2+) ion per subunit. Activated by ascorbate. Antibiotic biosynthesis; neopentalenolactone biosynthesis. Accumulation of pentalenolactone D. S.avermitilis does not produce pentalenolactone itself in vivo but instead a group of new metabolites that are neopentalenolactone derivatives. Belongs to the TfdA dioxygenase family.