Streptomyces rhizosphaericola sp. nov., an actinobacterium isolated from the wheat rhizosphere.

A novel actinobacterium, designated strain 1AS2c, was isolated from the wheat rhizosphere collected from the Brazilian Cerrado biome. A polyphasic approach, including phenotypic characterization and phylogenetic multilocus sequence analysis (MLSA), was used to determine the taxonomic position of this strain. Analysis of the 16S rRNA gene sequence indicated that the novel strain is closely related to Streptomyces cavourensis NBRC 13026, Streptomyces albolongus NBRC 13465 and Streptomyces araujoniae ASBV-1, sharing a similarity value of 98.2, 98.1 and 97.9 %, respectively. Additionally, MLSA of five housekeeping genes (atpD, gyrB, recA, rpoB and trpB) showed evolutionary distances beyond the 0.007 threshold, as well as low DNA-DNA relatedness between strain 1AS2c and its closest phylogenetic neighbours (S. cavourensis NBRC 13026, S. albolongus NBRC 13465 and S. araujoniae ASBV-1: 56, 62.5 and 63.0 %, respectively), indicating a new phylogenetic lineage. The phylogenetic, chemotaxonomic and phenotypic characteristics support the assignment of strain 1AS2c to the genus Streptomyces, representing a novel species. It is concluded that strain 1AS2c (=CMAA 1679=NRRL B-65479=DSM 105299) can be classified as the type strain of a novel species of the genus Streptomyces, for which the name Streptomyces rhizosphaericola sp. nov. is proposed.