A novel actinomycete, strain S187 T , was isolated from a marine sediment sample collected from Xinghai Bay, Dalian, China. Growth occurred on ISP medium 2 containing 0-9 % NaCl and at pH 6.0-9.0 and 10-45 6C. The cell wall of strain S187T contained the isomer LL-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinones were MK-9(H 6 ) (40.8 %), MK-9(H 8 ) (38.2 %) and MK-9(H 2 ) (8.8 %). The major fatty acids were iso-C 16 : 0 (29.6 %), anteiso-C 15 : 0 (14.0 %) and anteiso-C 17 : 0 (11.6 %). Cells contained phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidylinositol mannosides and one unknown phospholipid. The G+C content of the genomic DNA was 72.01 mol%. The 16S rRNA gene sequence of the isolate had similarities of 98.1 and 97.5 % with those of Streptomyces flavofuscus NRRL B-8036 T (5DSM 41426 T ) and Streptomyces albiaxialis DSM 41799 T , respectively, showing that the novel strain should be assigned to the genus Streptomyces. DNA-DNA hybridizations with the two above-mentioned Streptomyces species showed 31.4 and 46.9 % relatedness, respectively. Moreover, the three strains differed in some physiological and biochemical properties. Thus, on the basis of phenotypic and genotypic analyses, it is proposed that strain S187 T represents a novel species of the genus Streptomyces, for which the name Streptomyces xinghaiensis sp. nov. is proposed; the type strain is S187 T (5NRRL , 2006). Dalian is a coastal city located in the southernmost part of the Liaodong Peninsula, China, which has a very long coastline of 1906 km. However, the possible abundance of marine actinobacteria remains largely unexplored, except for some reports on sponge-derived marine actinobacteria (Zhang et al., 2006). During our screening of marine actinobacteria from sediment samples taken from the sea in the Dalian area, strain S187 T was recovered from a sediment sample collected from Xinghai Bay. In this study, strain S187T was characterized using a polyphasic taxonomic approach; it isThe GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain S187T is EF577247.A scanning electron micrograph of strain S187 T , a phylogenetic tree based on 16S rRNA gene sequences of S187T and related strains constructed using the maximum-parsimony method and antimicrobial activities of S187 T and closely related strains are available as supplementary material with the online version of this paper. proposed that this strain represents a novel species of the genus Streptomyces. International Journal of Systematic and Evolutionary MicrobiologyStrain S187 T was isolated from a marine sediment sample from Xinghai Bay, Dalian, China, after 2 weeks incubation at 28 u C on Bennett's agar (Margalith & Beretta, 1960). Morphological, physiological and biochemical characterizations of strain S187T were carried out following the standard protocol of the International Streptomyces Project (ISP; Shirling & Gottlieb, 1966, 1968a, b, 1969. Colour determination was assessed by comparison wit...

Due to the increasing emergence of drug-resistant bacteria and tumor cell lines, novel antibiotics with antibacterial and cytotoxic activities are urgently needed. Marine actinobacteria are rich sources of novel antibiotics, and here we report the discovery of a novel alkaloid, xinghaiamine A, from a marine-derived actinomycete Streptomyces xinghaiensis NRRL B24674T. Xinghaiamine A was purified from the fermentation broth, and its structure was elucidated based on extensive spectroscopic analysis, including 1D and 2D NMR spectrum as well as mass spectrometry. Xinghaiamine A was identified to be a novel alkaloid with highly symmetric structure on the basis of sulfoxide functional group, and sulfoxide containing compound has so far never been reported in microorganisms. Biological assays revealed that xinghaiamine A exhibited broad-spectrum antibacterial activities to both Gram-negative persistent hospital pathogens (e.g. Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) and Gram-positive ones, which include Staphylococcus aureus and Bacillus subtilis. In addition, xinghaiamine A also exhibited potent cytotoxic activity to human cancer cell lines of MCF-7 and U-937 with the IC50 of 0.6 and 0.5 µM, respectively.