Bacterial isolates from nematodes from Turkish soil samples were initially characterized by molecular methods and seven members of the genus Photorhabdus identified to the species level, using riboprint analyses and metabolic properties. Strain 07-5 (DSM 15195) was highly related to the type strain of Photorhabdus luminescens subsp. laumondii DSM 15139(T), and was regarded a strain of this subspecies. Strains 1121(T) (DSM 15194(T)), 68-3 (DSM 15198) and 47-10 (DSM 15197) formed one, strain 39-8T (DSM 15199(T)), 39-7 (DSM 15196) and 01-12 (DSM 15193) formed a second cluster that branched intermediate the three subspecies of Photorhabdus luminescens. Based upon moderate 165 rRNA gene sequence similarities and differences in metabolic properties among themselves and with type strains of the three subspecies we consider the two clusters to represent two new subspecies of Photorhabdus luminescens for which the names Photorhabdus luminescens subsp. kayaii, type strain 1121(T) (DSM 15194(T), NCIMB 13951(T)), and Photorhabdus luminescens subsp. thracensis subsp. nov., type strain 39-8(T) (DSM 15199(T), NCIMB 13952(T)) are proposed.