RESUMEN
Individual plants belonging to different species of the family Celastraceae collected from their natural habitats in South Africa (Putterlickia verrucosa (E. Meyer ex Sonder) Szyszyl., Putterlickia pyracantha (L.) Szyszyl., Putterlickia retrospinosa van Wyk and Mostert) and Brazil (Maytenus ilicifolia Mart. ex Reiss., Maytenus evonymoides Reiss., Maytenus aquifolia Mart.) were investigated for the presence of maytansinoids and of maytansine, an ansamycin of high cytotoxic activity. Maytansinoids were not detectable in plants grown in Brazil. Analysis of plants growing in South Africa, however, showed clearly that maytansinoids were present in some individual plants but were not detectable in others. Molecular biological analysis of a Putterlickia verrucosa cell culture gave no evidence for the presence of the aminohydroxybenzoate synthase gene which is unique to the biosynthesis of aminohydroxybenzoate, a precursor of the ansamycins including maytansinoids. Moreover, this gene was not detectable in DNA extracted from the aerial parts of Putterlickia plants. In contrast, observations indicate that this gene may be present in microbes of the rhizosphere of Putterlickia plants. Our observations are discussed with respect to the possibility that the roots of Putterlickia plants may be associated with microorganisms which are responsible for the biosynthesis of maytansine or maytansinoids.
Asunto(s)
Maitansina/análogos & derivados , Maitansina/análisis , Maytenus/química , 3-Desoxi-7-Fosfoheptulonato Sintasa/genética , Animales , Celastraceae/química , Células Cultivadas/química , Células Cultivadas/enzimología , ADN de Plantas/genética , Ambiente , Eucariontes/efectos de los fármacos , Hidroliasas/genética , Maitansina/farmacología , Penicillium/efectos de los fármacos , Raíces de Plantas/microbiología , Reacción en Cadena de la Polimerasa/métodos , Sensibilidad y EspecificidadRESUMEN
A polyphasic study was undertaken to establish the taxonomic position of a rhizosphere isolate that had been assigned provisionally to the genus Kitasatospora. The organism, isolate F18-98(T), was found to have chemical and morphological properties that were consistent with its classification as a Kitasatospora strain. Direct 16S rDNA sequence data confirmed the taxonomic position of the strain, following the generation of phylogenetic trees by using three treeing algorithms. The organism formed a 16S rDNA subclade with Kitasatospora azatica and Streptomyces kifunensis, but was distinguished readily from the latter by using a combination of biochemical and physiological properties. Genotypic and phenotypic data show that strain F18-98(T) should be classified in the genus Kitasatospora as a novel species, for which the name Kitasatospora putterlickiae sp. nov. is proposed; the type strain has been deposited in culture collections as strain F18-98(T) (=DSM 44665(T)=NCIMB 13932(T)). It is also proposed that Streptomyces kifunensis should be transferred to the genus Kitasatospora as Kitasatospora kifunensis comb. nov. An emended description of Streptomyces aureofaciens Duggar 1948 is also given.