Dehydrogenase that mediates the formation of 2,5-dihydroxybenzoic acid (2,5-DHBA), a siderophore that shares structural similarities with bacterial enterobactin and associates with lcn2 (By similarity). It thereby plays a key role in iron assimilation and homeostasis (PubMed:20550936). Also acts as a 3-hydroxybutyrate dehydrogenase (By similarity). (R)-3-hydroxybutanoate + NAD(+) = acetoacetate + H(+) + NADH Siderophore biosynthesis. Homotetramer. Detected in embryos. Morpholino knockdown of the protein causes no gross defects in embryos, with the exception of hypochromic blood due to decreased hemoglobin levels. Belongs to the short-chain dehydrogenases/reductases (SDR) family.