Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2008
Publication Date: 12/15/2008
Citation: Tamura, T., Ishida, Y., Otoguro, M., Hatano, K., Labeda, D.P., Price, N.P., Suzuki, K. 2008. Reclassification of Streptomyces caeruleus as a Synonym of Actinoalloteichus cyanogriseus and Reclassification of Streptomyces spheroides and Streptomyces laceyi as Later Synonyms of Streptomyces niveus. International Journal of Systematic and Evolutionary Microbiology. 58(12):2812-2814. Interpretive Summary: Researchers in Belgium and China in 2002 reclassified Streptomyces niveus and Streptomyces spheroides, the microbial species that produce the antibiotic novobiocin, as synonyms of the species Streptomyces caeruleus by analyzing the protein patterns of these strains. A recent study of strains of S. caeruleus held in a number of culture collections throughout the world found that the strain in the Belgian Culture Collection was not authentic and that S. caeruleus is actually the same as a species of another genus, Actinalloteichus cyanogriseus. During the process of correcting the original misclassification of the novobiocin-producing species, it was discovered that they were genetically and morphologically identical and, using recently collected molecular systematic data, that Streptomyces laceyi was also identical to S. niveus and S. spheroides. Examination of all three species by matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed that they formed exactly the same metabolic products, even though S. laceyi was not previously reported to produce novobiocin. This demonstrated the value of molecular systematic studies combined with newer mass spectrometric techniques in the search for potentially new microbial products. A proposal was made to recognize the name Streptomyces niveus, the oldest published species name, for these strains, and the other species names would be then considered synonyms. This study demonstrated the value of the combination of molecular phylogenetic studies with newer mass spectrometric technologies to elucidate previously unknown biosynthetic capabilities which could be extremely useful to biotechnology researchers searching for novel microbial products.
Technical Abstract: Lanoot et al. (2002) proposed that Streptomyces caeruleus was an earlier heterotypic synonym for both Streptomyces niveus and Streptomyces spheroides. Phylogenetic analysis of the almost complete 16S rRNA gene sequences of the Streptomyces caeruleus type strains NBRC 13344T, JCM 4014T and NRRL B-2194T revealed that S. caeruleus is closely related to Actinoalloteichus cyanogriseus and not S. niveus, S. spheroides or any other species of the genus Streptomyces. Moreover, the cell wall diamino acid in S. caerulus was found to be meso-diaminopimelic acid and DNA–DNA hybridization revealed that S. caeruleus NBRC 13344T is the same species as A. cyanogriseus NBRC 14455T. Based on these chemotaxonomic and phylogenetic data, we propose that Streptomyces caeruleus (Baldacci 1944) Pridham et al. 1958 be reclassified as a junior synonym of Actinalloteichus cyanogriseus Tamura et al. 2000. Furthermore, based on phylogenetic, morphological and MALDI-TOF MS analyses it is proposed that the validly published species Streptomyces laceyi Manfio et al. 2004 and Streptomyces spheroides Wallick et al. 1956 be reclassified as later synonyms of Streptomyces niveus Smith et al. 1956.