The title compound, C(10)H(11)NO(4), was extracted from a culture broth of Penicillium verruculosum YL-52. The mol-ecular structure is essentially planar, with an r.m.s. deviation of 0.01342 (2) Å for the non-H atoms. In the crystal structure, adjacent mol-ecules are connected into a centrosymmetric dimer through a pair of O-H⋯O hydrogen bonds. The dimers are further extended into a chain by weak C-H⋯O hydrogen bonds.