Catalyzes the oxidation of 1-deoxy-11-beta-hydroxypentalenic acid to 1-deoxy-11-oxopentalenic acid in the biosynthesis of neopentalenolactone antibiotic. 1-deoxy-11beta-hydroxypentalenate + NAD(+) = 1-deoxy-11-oxopentalenate + H(+) + NADH kcat is 0.65 sec(-1). Optimum pH is 8.0. Antibiotic biosynthesis; neopentalenolactone biosynthesis. S.avermitilis does not produce pentalenolactone itself in vivo but instead a group of new metabolites that are neopentalenolactone derivatives. Belongs to the short-chain dehydrogenases/reductases (SDR) family.