Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2009
Publication Date: 11/9/2009
Citation: Labeda, D.P., Price, N.P., Donahue, J.M., Williams, N.M., Sells, S.F. 2009. Streptomyces atriruber sp. nov. and Streptomyces silaceus sp. nov.: New Species of Equine Origin. International Journal of Systematic and Evolutionary Microbiology. 59(11):2899-2903. Interpretive Summary: Nocardioform placentitis is an emerging disease in thoroughbred mares and can cause economic loss to breeders when affected foals are weakened, still-borne or aborted. The microorganisms generally found to be associated with infected regions in placentas are predominantly identified as either Crossiella equi or various Amycolatopsis species, but there have been several instances where other actinobacteria have been involved. Two different strains, tentatively belonging to the genus Streptomyces, were isolated from infected placentas in 1999. These were recently fully characterized during a study of the entire genus Streptomyces and it was determined that they represent previously unknown species, for which the names Streptomyces atriruber and Streptomyces silaceeus are proposed. Since 2007 two new strains of Streptomyces atriruber have been recovered from infected equine placentas, further suggesting that they could represent new emerging pathogens of horses. The descriptive data presented and the gene sequences deposited in public databases will be a valuable resource for veterinary pathologists and microbiologists to recognize and identify these microorganisms in veterinary clinical samples.
Technical Abstract: Actinomycete strains isolated from lesions on equine placentas in Kentucky were subjected to polyphasic taxonomic identification. On the basis of phylogenetic analysis of 16S rRNA gene sequences, morphological observations, and the presence of the LL-diaminopimelic acid as the diamino-acid in whole-cell hydrolysates, the isolates clearly belong to the genus Streptomyces. Analyses of the phylogenetic position of strains NRRL B-24165 and NRRL B-24166 based on 16S rRNA gene sequences of all valid Streptomyces species as well as evaluation of morphological and physiological characteristics demonstrated that they could be differentiated from all known species and therefore represent novel species. It is proposed that new species be described for these strains, Streptomyces atriruber sp. nov. NRRL B-24165T (= DSM 41860T) and Streptomyces silaceus sp. nov. NRRL B-24166T (= DSM 41861T). These species names are based on the distinctive color of the substrate mycelium of these strains, dark red and deep orange-yellow, respectively.