Pseudomonas granadensis sp. nov., a new bacterial species isolated from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain.

During the course of screening bacterial isolates as sources of as-yet unknown bioactive compounds with pharmaceutical applications, a chemo-organotrophic, Gram-negative bacterium was isolated from a soil sample taken from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain. Strain F-278,770(T) was oxidase- and catalase-positive, aerobic, with a respiratory type of metabolism with oxygen as the terminal electron acceptor, non-spore-forming and motile by one polar flagellum, although some cells had two polar flagella. Phylogenetic analysis of the 16S rRNA, gyrB, rpoB and rpoD genes revealed that strain F-278,770(T) belongs to the Pseudomonas koreensis subgroup (Pseudomonas fluorescens lineage), with Pseudomonas moraviensis, P. koreensis, P. baetica and P. helmanticensis as its closest relatives. Chemotaxonomic traits such as polar lipid and fatty acid compositions and G+C content of genomic DNA corroborated the placement of strain F-278,770(T) in the genus Pseudomonas. DNA-DNA hybridization assays and phenotypic traits confirmed that this strain represents a novel species of the genus Pseudomonas, for which the name Pseudomonas granadensis sp. nov. is proposed. The type strain is F-278,770(T) ( = DSM 28040(T) = LMG 27940(T)).

Isolation, structure, and antibacterial activities of lucensimycins D-G, discovered from Streptomyces lucensis MA7349 using an antisense strategy.

Bacterial resistance to existing antibiotics continues to grow, necessitating the discovery of new compounds of this type. Antisense-based whole-cell target-based screening is a new and highly sensitive antibiotic discovery approach that has led to a number of new natural product antibiotics. Screening with a rpsD-sensitized strain led to the discovery of a number of natural product polyketides from Streptomyces lucensis. Complete workup of the fermentation extract of this strain allowed for the isolation of seven new compounds, lucensimycins A-G (1-3, 4a, 5-7), with varying degrees of antibacterial activities. Lucensimycin E (5) exhibited the best activity and showed MIC values of 32 microg/mL against Staphylococcus aureus and 8 microg/mL against Streptococcus pneumoniae. The isolation, structure elucidation, and antibacterial activities of four new members, lucensimycins D-G, are described. Lucensimycins D (4a) and E (5) are N-acetyl-l-cysteine adducts of lucensimycin A (1). Semisynthesis of lucensimycins D and E from lucensimycin A has also been described. Lucensimycins F and G are myo-inositolyl-alpha-2-amino-2-deoxy-l-idosyl amide derivatives of lucensimycins D and E, respectively. The relative configuration of these compounds was determined, in part, by molecular dynamics simulations.

Anthelmintic macrolactams from Nonomuraea turkmeniaca MA7364.

Two new macrolactams, 6-desmethyl-N-methylfluvirucin A1 (1) and N-methylfluvirucin A1 (2), have been isolated from the acetone extract of Nonomuraea turkmeniaca MA7364. These compounds were isolated by bioassay-guided fractionation as part of our search for new anthelmintics. The structures of these compounds were elucidated by comparison of their NMR and MS data to those of previously reported fluvirucins and confirmed by 2D NMR. Compound 1 exhibited in vitro activity (EC(90) 15 +/- 5 microg/mL) against Haemonchus contortus larvae, whereas compound 2, while a bit less active in vitro (EC(90) 29 +/- 8 microg/mL), showed modest in vivo activity against a surrogate organism, Heligmosomoides polygyrus in mice, at 50 mg/kg.

Durhamycin A, a potent inhibitor of HIV Tat transactivation.

Tat is a small HIV protein essential for both viral replication and the progression of HIV disease. In our efforts to discover Tat inhibitors from natural product screening of microbial fermentation extracts, we discovered durhamycin A (1) as a potent inhibitor (IC(50) = 4.8 nM) of Tat transactivation. Detailed NMR and MS/MS studies were utilized to elucidate the structure of 1 as a new member of the aureolic acid family of antibiotics. It consists of tetrasaccharide and disaccharide moieties attached to the aglycone, which is hitherto unknown in the aureolic acid family. Three other novel analogues, durhamycin B (2), compound (3), and the aglycone (4), were also discovered or chemically prepared that were less potent than durhamycin A.