Chemical examination of an extract from an Erythrobacter sp. isolated from mangrove sediments yielded erythrazoles A (1) and B (2). The erythrazoles are of mixed biosynthetic origin containing a tetrasubstituted benzothiazole, an appended diterpene side chain, and a glycine unit. Erythrazole B is cytotoxic to a panel of non-small cell lung cancer (NSCLC) cell lines, with IC(50) values of 1.5, 2.5, and 6.8 μM against H1325, H2122, and HCC366, respectively.