The taxonomic position of a group of moderately thermophilic actinomycetes isolated from vegetable matter was determined using a suite of genotypic and phenotypic properties. The organisms were found to share a range of chemical and morphological markers typical of members of the genus Amycolatopsis. A representative of the group, strain K24 T , formed a distinct phyletic line within the range of variation occupied by the genus Amycolatopsis in the 16S rDNA tree. The strains have many phenotypic properties in common and some of these distinguish the group from representatives of the validly described species of Amycolatopsis. It is clear from the combined datasets that the strains merit recognition as a new species of Amycolatopsis. The name proposed for the new species is Amycolatopsis sacchari ; the type strain is K24 T ( l DSM 44468 T l KCTC 9863 T ).Keywords : Amycolatopsis sacchari sp. nov., polyphasic taxonomy, 16S rDNA sequencing
INTRODUCTIONThe family Pseudonocardiaceae was proposed by Embley et al. (1988a) to accommodate actinomycetes which contained meso-diaminopimelic acid (meso-A #pm ), arabinose and galactose in their wall peptidoglycan (wall chemotype IV sensu Lechevalier & Lechevalier, 1970) but lacked mycolic acids. Members of the family are currently classified in the genera Actinobispora, Amycolatopsis, Kibdelosporangium, Prauserella, Pseudonocardia (including Amycolata), Saccharomonospora, Saccharopolyspora and Thermocrispum (Kim & Goodfellow, 1999 ;Xu et al., 1999 ;Labeda & Kroppenstedt, 2000).The genus Amycolatopsis was established by Lechevalier et al. (1986) to accommodate four species which had been misclassified in the genus Nocardia. At present, the genus contains 10 validly described species which form a phyletic line within the evolutionary radiation occupied by the family Pseudonocardiaceae (Embley et al., 1988a ;Chun et al., 1999 three of these species, namely, Amycolatopsis fastidiosa (ex Celmer et al. 1977) Henssen et al. 1987, Amycolatopsis methanolica De Boer et al. 1990 and Amycolatopsis thermoflava Chun et al. 1999 grow well between 50 and 60 mC and hence can be considered as thermophilic actinomycetes (Cross, 1968 ;Brock, 1986 Lechevalier et al. 1986, are mesophilic and do not grow above 45 mC.The genus Amycolatopsis can be distinguished from members of other genera classified in the family Pseudonocardiaceae using a combination of chemical and morphological markers (Kim & Goodfellow, 1999). Similarly, members of validly described species of Amycolatopsis can be differentiated from one another using a battery of phenotypic properties (Chun et al., 1999 M. Goodfellow and others source of commercially significant antibiotics (Embley, 1992).The present investigation was designed to establish the taxonomic position of Amycolatopsis-like isolates which formed a distinct cluster in numerical phenetic surveys of the family Pseudonocardiaceae and related taxa (Mattinson-Rose, 1986 ;Whitehead, 1989). Genotypic and phenotypic data show that these strains should be recognized as a new s...