The type II polyketide synthase (PKS) natural product enterocin (1) was isolated from a mangrove-derived novel species Streptomyces qinglanensis 172205 guided by genome sequence, and its putative biosynthetic gene cluster was revealed. Its natural analogues 5-deoxyenterocin (2) and wailupemycin A-C (3-5) were also identified by tandem mass spectrometry. By feeding experiments with aryl acids, strain 172205 was proved to incorporate partial exogenous starter units into enterocin- and wailupemycin-based analogues, thus being a new and suitable microorganism for engineering unnatural enc-derived polyketide metabolites. In addition, biological assays indicated that enterocin showed obvious inhibitory activity against beta-amyloid protein (A beta(1-42)) fibrillation and moderate cytotoxicity against HeLa and HepG2 for the first time.