Williamsia aurantiacus sp. nov. a novel actinobacterium producer of antimicrobial compounds isolated from the marine sponge.

An antibiotic-producing actinobacterium, designated isolate B375^T, was isolated from marine sponge Glodia corticostylifera collected from Praia Guaecá, São Paulo, Brazil (23°49S; 45°25W), and its taxonomic position established using data from a polyphasic study. The organism showed a combination of morphological, physiological, biochemical and chemotaxonomic characteristics consistent with its classification in the genus Williamsia. Comparative 16S rRNA gene sequence analysis indicated that the strain B375^T was most closely related to Williamsia serinedens DSM 45037^T and Williamsia spongiae DSM 46676^T and having 99.43% and 98.65% similarities, respectively, but was distinguished from these strains by a low level of DNA–DNA relatedness (53.2–63.2%) and discriminatory phenotypic properties. Chemotaxonomic investigations revealed the presence of cell-wall chemotype IV and N-glycolated muramic acid residues present in the wall cells. The cells contained C_16:0 (23.3%), C_18:0 10-methyl (23.2%) and C_18:1 ω9c (21.6%) as the major cellular fatty acids. The strain B375^T inhibited growing of Staphylococcus aureus and Colletotrichum gloeosporioides strains and was considered a producer of antimicrobial compounds. Based on the data obtained, the isolate B375^T (= CBMAI 1090^T = DSM 46677^T) should, therefore, be classified as the type strain of a novel species of the genus Williamsia, for which the name Williamsia aurantiacus sp. nov. is proposed. [ABSTRACT FROM AUTHOR]