Catalyzes the NADH-dependent reduction of beta-ketoacyl derivatives (PubMed:19685079, PubMed:21081168, PubMed:23163771). Can accept the beta-oxo fatty acyl group covalently linked with CoA or ACP for catalysis (PubMed:23163771). Highly specific for NADH (PubMed:19685079, PubMed:21081168). Could be involved in fatty acid biosynthesis (Probable). a (3R)-hydroxyacyl-[ACP] + NAD(+) = a 3-oxoacyl-[ACP] + H(+) + NADH 3-hydroxybutanoyl-CoA + NAD(+) = acetoacetyl-CoA + H(+) + NADH (3R)-hydroxyhexanoyl-CoA + NAD(+) = 3-oxohexanoyl-CoA + H(+) + NADH (3R)-3-hydroxydecanoyl-CoA + NAD(+) = 3-oxodecanoyl-CoA + H(+) + NADH kcat is 454 sec(-1) with acetoacetyl-CoA as substrate. kcat is 169 sec(-1) with 3-hydroxybutanoyl-CoA as substrate. kcat is 319 sec(-1) with NADH as substrate. kcat is 83 sec(-1) with NAD(+) as substrate. Lipid metabolism; fatty acid metabolism. Homodimer. Contains an N-terminal flavodoxin-type domain and a C-terminal ketoreductase domain (PubMed:21081168). The C-terminal residues participate in intercatalytic domain interaction and play a pivotal role in stabilization of loop I, which is responsible for interaction with phosphopentethine moiety-linked fatty acyl substrates of CoA or ACP (PubMed:23163771). Restores respiratory growth of S.cerevisiae oar1 deletion mutant. Was identified as a putative drug target. Inhibited by triazole linked polyphenol-gallol hybrids and triazole linked polyphenol-aminobenzene hybrids. These compounds may be possible candidates for alternate anti-tubercular drugs. Belongs to the short-chain dehydrogenases/reductases (SDR) family.