Streptomyces yunnanensis sp. nov., a mesophile from soils in Yunnan, China Qi Zhang, Wen-Jun Li, Xiao-Long Cui, Ming-Gang Li, Li-Hua Xu and Cheng-Lin Jiang Correspondence Cheng-Lin Jiang lihxu@ynu.edu.cn The Key Laboratory for Microbial Resources of Ministry of Education, PR China, Yunnan Institute of Microbiology, Yunnan University, Kunming, Yunnan 650091, PR China A strain was isolated from red soil from the suburb of Kunming in Yunnan, China, during the screening of agricultural antibiotics which prevented and cured wheat-stem rust. This isolate, designated YIM 41004 T (=CGMCC 4.1004 T =DSM 41793 T ), was identified by a polyphasic approach. The test results suggested that this strain was clearly assigned to the genus Streptomyces and found to be marginally close to Williams cluster 32 based on the morphological and physiological data. The almost-complete 16S rRNA gene sequence of the strain was determined and compared with those of representative streptomycetes. The phylogenetic tree confirmed its membership in the genus Streptomyces and demonstrated that this strain represented a separate phyletic line in a clade encompassed by streptomycetes within cluster 32. Based on the polyphasic evidence, it is therefore proposed that strain YIM 41004 T should be classified as Streptomyces yunnanensis sp. nov. INTRODUCTION The numerical taxonomic study of the genus Streptomyces by Williams et al. (1983) and the Streptomyces chapter in vol. 4 of Bergey’s Manual of Systematic Bacteriology (Williams et al., 1989) delineated the Streptomyces violaceusniger cluster in terms of morphology for strains having grey, rough- surfaced spores in spiral chains, which encompassed S. violaceusniger, several Streptomyces hygroscopicus strains, Streptomyces sparsogenes and Streptomyces melanosporofa- ciens. A study of levels of DNA relatedness among strains of S. violaceusniger and other related taxa belonging to the S. violaceusniger cluster by Williams et al. (1983, 1989) demonstrated that the Streptomyces violaceusniger pheno- typic cluster is heterogeneous in DNA relatedness among strains at a level of >70 %, and strains in this cluster should be considered to be four distinct species, S. melanosporofaciens, S. sparsogenes, S. violaceusniger and S. hygroscopicus (Streptomyces endus was assigned as a subjective synonym in the revised description of S. hygroscopicus) (Labeda & Lyons, 1991). A numerical classification, using miniaturized physiological tests, of the genera Streptomyces and Streptoverticillium by Ka ¨mpfer et al. (1991) showed that the distinct species described by Labeda & Lyons (1991) in Williams cluster 32 were distributed into clusters 10, 41, 51, 53, 54 and 85. In the course of screening agricultural antibiotics that prevent and cure wheat-stem rust, strain YIM 41004 T was isolated from soil samples in Yunnan. It produces the antifungal agent cycloheximide. It is morphologically and physiologically similar to strains assigned to the Streptomyces violaceusniger cluster (Williams et al., 1983, 1989). The taxonomic results are reported in this paper. METHODS Organism. Strain YIM 41004 T was isolated from the red soil of suburb of Kunming of Yunnan, China. The strain was maintained by cultivation on 38 # agar medium that contained (per litre) 4 g glu- cose, 4 g yeast extract, 5 g malt extract and vitamin/amino acid mix- ture (1 mg each of vitamin B 1 , vitamin B 2 , vitamin B 6 , biotin, nicotinic acid and phenylalanine, and 0?3g alanine), with pH adjusted to 7?2, and incubated at 25–30 ˚ C for 7–15 days. The effect of temperature on growth rate was determined on 38 # agar at 24– 32 ˚ C at intervals of 2 ˚ C; optimum growth was at 28 ˚ C. Phenotypic characterization. The medium used for morpho- logical studies was yeast extract-malt extract agar (International Streptomyces Project medium no. 2, ISP 2) (Shirling & Gottlieb, 1966) and the incubation time of the pure culture was 7–15 days at 28–30 ˚ C. Morphological observations were made by using optical and electron microscopy (model EPMA-8705). Cultural and physio- logical characteristics of strain YIM 41004 T were determined accord- ing to the methods proposed by Shirling & Gottlieb (1966) and Williams et al. (1983). Colour determinations were made by com- paring the cultures with colour chips from the ISCC–NBS Color Charts Standard Sample No. 2106 (Kelly, 1964). Chemotaxonomy. Cell wall was purified and analysed by the methods of Lechevalier & Lechevalier (1980). The procedures of Becker et al. (1964) and Lechevalier & Lechevalier (1980) were used for analyses of whole-cell chemical compositions. Abbreviation: ISP, International Streptomyces Project. The GenBank/EMBL/DDBJ accession number for the partial 16S rDNA sequence of strain YIM 41004 T is AF346818. 01851 G 2003 IUMS Printed in Great Britain 217 International Journal of Systematic and Evolutionary Microbiology (2003), 53, 217–221 DOI 10.1099/ijs.0.01851-0