**Characterization of** *Streptomyces sporangiiformans* **sp. nov., a Novel Soil Actinomycete with Antibacterial Activity against** *Ralstonia solanacearum*

**Junwei Zhao 1,**†**, Liyuan Han 1,**†**, Mingying Yu 1, Peng Cao 1, Dongmei Li 1, Xiaowei Guo 1, Yongqiang Liu 1, Xiangjing Wang 1,\* and Wensheng Xiang 1,2,\***

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Received: 27 August 2019; Accepted: 13 September 2019; Published: 17 September 2019

**Abstract:** *Ralstonia solanacearum* is a major phytopathogenic bacterium that attacks many crops and other plants around the world. In this study, a novel actinomycete, designated strain NEAU-SSA 1T, which exhibited antibacterial activity against *Ralstonia solanacearum*, was isolated from soil collected from Mount Song and characterized using a polyphasic approach. Morphological and chemotaxonomic characteristics of the strain coincided with those of the genus *Streptomyces*. The 16S rRNA gene sequence analysis showed that the isolate was most closely related to *Streptomyces aureoverticillatus* JCM 4347<sup>T</sup> (97.9%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain formed a cluster with *Streptomyces vastus* JCM4524T (97.4%), *S. cinereus* DSM43033T (97.2%), *S. xiangluensis* NEAU-LA29T (97.1%) and *S. flaveus* JCM3035<sup>T</sup> (97.1%). The cell wall contained *LL*-diaminopimelic acid and the whole-cell hydrolysates were ribose, mannose and galactose. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), hydroxy-phosphatidylethanolamine (OH-PE), phosphatidylinositol (PI), two phosphatidylinositol mannosides (PIMs) and an unidentified phospholipid (PL). The menaquinones were MK-9(H4), MK-9(H6), and MK-9(H8). The major fatty acids were *iso*-C17:0, C16:0 and C17:1 ω9c. The DNA G+C content was 69.9 mol %. However, multilocus sequence analysis (MLSA) based on five other house-keeping genes (*atp*D, *gyr*B, *rec*A, *rpo*B, and *trp*B), DNA–DNA relatedness, and physiological and biochemical data showed that the strain could be distinguished from its closest relatives. Therefore, it is proposed that strain NEAU-SSA 1T should be classified as representatives of a novel species of the genus *Streptomyces*, for which the name *Streptomyces sporangiiformans* sp. nov. is proposed. The type strain is NEAU-SSA 1T (=CCTCC AA 2017028<sup>T</sup> = DSM 105692T).

**Keywords:** *Streptomyces sporangiiformans* sp. nov.; antibacterial activity; multilocus sequence analysis; *Ralstonia solanacearum*
