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

An antibiotic-producing actinobacterium, designated isolate B375, 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 was most closely related to Williamsia serinedens DSM 45037 and Williamsia spongiae DSM 46676 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 (23.3%), C 10-methyl (23.2%) and C ω9c (21.6%) as the major cellular fatty acids. The strain B375 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 (= CBMAI 1090 = DSM 46677) 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.