eThe genome sequences of eight Streptomyces phages are presented, four of which were isolated for this study. Phages R4, TG1, Hau3, and SV1 were isolated previously and have been exploited as tools for understanding and genetically manipulating Streptomyces spp. We also extracted five apparently intact prophages from recent Streptomyces spp. genome projects and, together with six phage genomes in the database, we analyzed all 19 Streptomyces phage genomes with a view to understanding their relationships to each other and to other actinophages, particularly the mycobacteriophages. Fifteen of the Streptomyces phages group into four clusters of related genomes. Although the R4-like phages do not share nucleotide sequence similarity with other phages, they clearly have common ancestry with cluster A mycobacteriophages, sharing many protein homologues, common gene syntenies, and similar repressor-stoperator regulatory systems. The R4-like phage Hau3 and the prophage StrepC.1 (from Streptomyces sp. strain C) appear to have hijacked a unique adaptation of the streptomycetes, i.e., use of the rare UUA codon, to control translation of the essential phage protein, the terminase. The Streptomyces venezuelae generalized transducing phage SV1 was used to predict the presence of other generalized transducing phages for different Streptomyces species. Bacteriophages are the most abundant and diverse genetic entities on planet Earth. Despite this, it has been proposed that all double-stranded DNA (dsDNA) phages share the same gene pool and that there are clear examples where common ancestry is evident between orthologous gene pairs from very different phages (for example, the capsid-encoding genes from coliphage HK97 and Streptomyces phage C31) (1, 2). Understanding the mechanisms through which phages generate such vast diversity is still a challenge, but the drivers of selection and adaptation to growth in different bacterial hosts are clearly strong influences. We are interested in the adaptations of phages that infect the Actinobacteria, a class of high-GC, Gram-positive bacteria that have very diverse morphology, physiology, and growth properties.Actinobacteria, particularly those in the genus Streptomyces, have a remarkable capacity to synthesize a diverse array of secondary metabolites of all the major classes. Indeed, 70% of clinically useful antibiotics come from Streptomyces spp. Genetic tools derived from Streptomyces phages have been invaluable in investigations aimed at understanding the fundamental biology of these bacteria and in manipulating antibiotic pathways (3, 4). Phages were used initially as cloning vectors, but since the early 1990s, integrating plasmid vectors based on phage-encoded site-specific recombination systems have been widely used, enabling the stable insertion of gene constructs into a defined site (attB) in the chromosome (5, 6). Moreover, as streptomycetes are mycelial and undergo a developmental cycle, phages that infect this group of bacteria are likely to have undergone host-specific evolu...

We report the draft genome of Streptomyces rimosus (ATCC 10970), a soil isolate that produces oxytetracycline, a commercially important and clinically useful antibiotic.

Endophytic bacteria, such as Streptomyces, have the potential to act as a source for novel bioactive molecules with medicinal properties. The present study was aimed at assessing the antimalarial activity of crude extract isolated from various strains of actinobacteria living endophytically in some Malaysian medicinal plants. Using the four day suppression test method on male ICR strain mice, compounds produced from three strains of Streptomyces (SUK8, SUK10, and SUK27) were tested in vivo against Plasmodium berghei PZZ1/100 in an antimalarial screen using crude extracts at four different concentrations. One of these extracts, isolated from Streptomyces SUK10 obtained from the bark of Shorea ovalis tree, showed inhibition of the test organism and was further tested against P. berghei-infected mice for antimalarial activity at different concentrations. There was a positive relationship between the survival of the infected mouse group treated with 50 µg/kg body weight (bw) of ethyl acetate-SUK10 crude extract and the ability to inhibit the parasites growth. The parasite inhibition percentage for this group showed that 50% of the mice survived for more than 90 days after infection with the parasite. The nucleotide sequence and phylogenetic tree suggested that Streptomyces SUK10 may constitute a new species within the Streptomyces genus. As part of the drug discovery process, these promising finding may contribute to the medicinal and pharmaceutical field for malarial treatment.

e Corynebacterium pseudotuberculosis causes disease in several animal species, although distinct biovars exist that appear to be restricted to specific hosts. In order to facilitate a better understanding of the differences between biovars, we report here the complete genome sequence of the equine pathogen Corynebacterium pseudotuberculosis strain 1/06-A.

e Here, we report the whole-genome sequences of two ovine-pathogenic Corynebacterium pseudotuberculosis isolates: strain 3/99-5, which represents the first C. pseudotuberculosis genome originating from the United Kingdom, and 42/02-A, the second from Australia. These genome sequences will contribute to the objective of determining the global pan-genome of this bacterium.