DNA–DNA hybridization experiments were performed using the method described by Ziemke et al. (1998), except that, for nick translation, 2 mg DNA was labelled during a 3 h incubation at 15 uC. Hybridization with labelled DNA from the type strains of related Nocardia species gave the following results: N. speluncae YEME N2-11T (18.1 %, reciprocal analysis 14.1 %), N. jinanensis DSM 45048T (34.4, 13.1 %) and N. rhamnosiphila DSM 45147T (15.6, 16.2 %).