title: Morphological, physiological, and molecular characterization of a newly isolated steroid-degrading actinomycete, identified as rhodococcus ruber strain Chol-4.
abstract: The aerobic degradation of cholesterol, testosterone, androsterone, progesterone, and further steroid compounds as sole carbon source has been observed in the newly isolated bacterial Gram-positive strain Chol-4. The 16S rRNA gene sequence shares the greatest similarity with members of the genus Rhodococcus, with the closest shared nucleotide identities of 98-99% with Rhodococcus ruber (DSM 43338(T)) and Rhodococcus aetherivorans (DSM 44752(T)). Phylogenetic analysis of Rhodococcus 16S rRNA gene sequences consistently places strain Chol-4 in a clade shared with those both type strains within the Rhodococcus rhodochrous subclade. The results of DNA-DNA hybridization against its two phylogenetically closest neighbors as well as the results of morphological, physiological, and biochemical tests allowed genotypic and phenotypic differentiation of strain Chol-4 from Rhodococcus ruber (DSM 43338(T)) on the species level and from the other validly described Rhodococcus species on the genus level. Strain Chol-4 therefore merits recognition as a novel strain of the species Rhodococcus ruber and demonstrates for the first time the capability of this species to utilize a great variety of steroid compounds as growth substrates never shown for other species of this genus so far. The genome of strain Chol-4 harbors at least one gene cluster that may be responsible for the degradation of steroid compounds. This gene cluster was identified in a cloned 5458 bp BamHI-EcoRV DNA fragment and compared to similar genes from other Gram-positive and Gram-negative bacteria described so far.
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Universidad Complutense de Madrid, Madrid, 28040, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Fernández de Las Heras
authors.forename: Esther
authors.initials: E
authors.lastname: García Fernández
authors.forename: J
authors.initials: J
authors.lastname: María Navarro Llorens
authors.forename: Julián
authors.initials: J
authors.lastname: Perera
authors.forename: Oliver
authors.initials: O
authors.lastname: Drzyzga
mesh_terms: D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012240:Rhodococcus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D013256:Steroids / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D013256:Steroids
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