Streptosporangium lutulentum sp. nov., Streptosporangium fenghuangense sp. nov. and Streptosporangium corydalis sp. nov., three novel actinobacterial species isolated from National Forest Park of Fenghuang Mountain

Streptosporangium minutum sp. nov., isolated from garden soil exposed to microwave radiation

The actinobacterium, strain M26^T, was isolated from garden soil that was pre-treated with microwave radiation. The soil sample was collected in Roodepoort, Gauteng Province, South Africa as part of an antibiotic-screening programme. The isolate produced branched vegetative mycelium with sporangiophores bearing small sporangia ranging from 3 to 6 μm in diameter. Rapid genus identification revealed that the isolate belongs to the genus Streptosporangium. To confirm this result, the strain was subjected to polyphasic taxonomic characterisation. Chemotaxonomic characteristics were as follows: meso-DAP in the peptidoglycan, the whole-cell hydrolysate yielded madurose, predominant menaquinones were MK9 (21%), MK9(H₂) (40%), MK9(H₄) (31%) and MK9(H₆) (3%); the polar lipid profile included an aminolipid, phosphoglycolipids, phosphatidylethanolamine, and phosphatidylmonomethylethanolamine. In addition, the fatty acid profile showed the presence of C_16:0 (12.8%), C_17:1ω8c (14.2%), and 10-methyl-C_17:0 (15.8%). Furthermore, 16S rRNA gene sequence phylogenetic analysis showed that the strain is closely related to members of the genus Streptosporangium, which supports its classification within the family Streptosporangiaceae. Strain M26^T exhibited antibiosis against a range of pathogenic bacteria, including, but not limited to Acinetobacter baumannii ATCC 19606^T, Enterobacter cloacae subsp. cloacae ATCC BAA-1143, Enterococcus faecalis ATCC 51299 (vancomycin resistant), Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19111, Mycobacterium tuberculosis H37Rv^T, Pseudomonas aeruginosa ATCC 27853, Salmonella enterica subsp. arizonae ATCC 13314^T, and the methicillin-resistant Staphylococcus aureus subsp. aureus ATCC 33591 (MRSA). The name Streptosporangium minutum is proposed with the type strain M26^T (=LMG 28850^T =NRRL B-65295^T).

Streptosporangium becharense sp. nov., an actinobacterium isolated from desert soil

The taxonomic position of a novel actinobacterium, strain SG1^T, isolated from a Saharan soil sample collected from Béni-Abbès, Béchar (south-west Algeria), was established by using a polyphasic approach. The micro-organism had morphological and chemical features that were consistent with its classification in the genus Streptosporangium. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose and glucose, but not madurose. The predominant menaquinones were MK-9(H2) and MK-9(H4). The polar lipid profile contained diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylhydroxymethylethanolamine, phosphatidylhydroxyethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. The predominant cellular fatty acids were C17 : 1ω8c, iso-C16 : 0, 10-methyl C17 : 0, C18 : 1ω9c and C17 : 0. 16S rRNA gene sequence similarity analysis supported the classification of the isolate in the genus Streptosporangium and indicated that it was related most closely to 'Streptosporangium subfuscum' DSM 46724 (99.7 % similarity), Streptosporangium pseudovulgare DSM 43181^T (98.7 %), Streptosporangium fragile DSM 43847^T (98.6 %) and Streptosporangium sandarakinum DSM 45763^T (98.5 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain SG1^T formed a cluster with its closest relative 'S. subfuscum' DSM 46724. However, DNA-DNA relatedness as well as physiological and chemotaxonomical analyses showed that strain SG1^T could be differentiated from its closest phylogenetic relatives. Therefore, it is proposed that strain SG1^T should be classified as representing a novel species in the genus Streptosporangium, for which the name Streptosporangiumbecharense sp. nov. is proposed. The type strain is SG1^T (=DSM 46887^T=CECT 8961^T).