Taxonomy and antimicrobial activities of a new Streptomyces sp. TN17 isolated in the soil from an oasis in Tunis

An actinomycete strain referred to as TN17 was screened for its antimicrobial activities. The taxonomic status of this strain was established. The organism was found to have morphological and chemotaxonomic characteristics typical of Streptomycetes. Based on the 16S rRNA nucleotide sequences, Streptomyces sp. TN17 was found to have a relationship with Streptomyces lilaceus, Streptomyces gobitricini and Streptomyces lavendofoliae. Combined analysis of the 16 S rRNA gene sequence (FN687757), phylogenetic analysis, fatty acids profile and physiological tests indicated that there are genotypic and phenotypic differences between TN17 and neighboring Streptomyces species’ neighbors. Therefore, TN17 is a novel species: Streptomyces sp. TN17 (=DSM 42020T=CTM50229T). A cultured extract of this strain inhibits the growth of several Gram positive and Gram negative bacteria and fungi

Taxonomy, purification and chemical characterization of four bioactive compounds from new Streptomyces sp. TN256 strain

A new actinomycete strain designated TN256, producing antimicrobial activity against pathogenic bacteria and fungi, was isolated from a Tunisian Saharan soil. Morphological and chemical studies indicated that strain TN256 belonged to the genus Streptomyces. Analysis of the 16S rDNA sequence of strain TN256 showed a similarity level ranging between 99.79 and 97.8% within Streptomyces microflavus DSM 40331T and Streptomyces griseorubiginosus DSM 40469T respectively. The comparison of its physiological characteristics showed significant differences with the nearest species. Combined analysis of the 16 S rRNA gene sequences (FN687758), fatty acids profile, and results of physiological and biochemical tests indicated that there were genotypic and phenotypic differentiations of that isolate from other Streptomyces species neighbours. These date strongly suggest that strain TN256 represents a novel species with the type strain Streptomyces TN256 (=CTM50228T). Experimental validation by DNA–DNA hybridization would be required for conclusive confirmation. Four active products (1–4) were isolated from the culture broth of Streptomyces TN256 using various separation and purification steps and procedures. 1: N-[2-(1H-indol-3-yl)-2 oxo-ethyl] acetamide ‘alkaloid’ derivative; 2: di-(2-ethylhexyl) phthalate, a phthalate derivative; 3: 1-Nonadecene and 4: Cyclo (l-Pro-l-Tyr) a diketopiperazine ‘DKP’ derivative. The chemical structure of these four active compounds was established on the basis of spectroscopic studies NMR and by comparing with data from the literature. According to our biological studies, we showed in this work that the pure compounds (1–4) possess antibacterial and antifungal activities

A single Streptomyces symbiont makes multiple antifungals to support the fungus farming ant Acromyrmex octospinosus

Attine ants are dependent on a cultivated fungus for food and use antibiotics produced by symbiotic Actinobacteria as weedkillers in their fungus gardens. Actinobacterial species belonging to the genera Pseudonocardia, Streptomyces and Amycolatopsis have been isolated from attine ant nests and shown to confer protection against a range of microfungal weeds. In previous work on the higher attine Acromyrmex octospinosus we isolated a Streptomyces strain that produces candicidin, consistent with another report that attine ants use Streptomyces-produced candicidin in their fungiculture. Here we report the genome analysis of this Streptomyces strain and identify multiple antibiotic biosynthetic pathways. We demonstrate, using gene disruptions and mass spectrometry, that this single strain has the capacity to make candicidin and multiple antimycin compounds. Although antimycins have been known for > 60 years we report the sequence of the biosynthetic gene cluster for the first time. Crucially, disrupting the candicidin and antimycin gene clusters in the same strain had no effect on bioactivity against a co-evolved nest pathogen called Escovopsis that has been identified in similar to 30% of attine ant nests. Since the Streptomyces strain has strong bioactivity against Escovopsis we conclude that it must make additional antifungal(s) to inhibit Escovopsis. However, candicidin and antimycins likely offer protection against other microfungal weeds that infect the attine fungal gardens. Thus, we propose that the selection of this biosynthetically prolific strain from the natural environment provides A. octospinosus with broad spectrum activity against Escovopsis and other microfungal weeds.Publisher PDFPeer reviewe

Draft Genome Sequence of Streptomyces phaeoluteigriseus DSM41896

The draft genome for the type strain Streptomyces phaeoluteigriseus DSM41896 (ISP 5182) is reported. It was classified as a member of the Streptomyces violaceusniger clade; however, a polyphasic study showed it was a separate species based on its distinct spore morphology and 16S rRNA sequence. The genome sequence confirms it as a separate species

Soil suppressiveness and functional diversity of the soil microflora in organic farming systems

Arable fields of 10 organic farms from different locations within the Netherlands were sampled in four subsequent years. The soil samples were analysed for disease suppressiveness against Rhizoctonia solani, Streptomyces scabies and Verticillium dahliae. Furthermore, a variety of microbial characteristics and chemical and physical soil properties were assessed. All these characteristics and different environmental factors were correlated by multivariate analyses. Significant differences in soil suppressiveness were found for all three diseases. Suppressiveness against Rhizoctonia was more or less consistent between the sampled fields in 2004 and 2005. This suppressiveness correlated with higher numbers of Lysobacter and Pseudomonas antagonists, as well as fungal diversity in DGGE patterns. Furthermore, results of 2006 showed that one year of grass-clover clearly stimulated Rhizoctonia suppression. Also Streptomyces soil suppressiveness was consistent between 2004 and 2005, but it concerned other soils than the ones which were suppressive against Rhizoctonia. Streptomyces suppression correlated with higher numbers of antagonists in general, Streptomyces and the fungal/bacterial biomass ratio, but with a lower organic matter content and respiration. Soil suppressiveness against Verticillium was not consistent between the years and therefore probably not related to soil factors

Termite nests as an abundant source of cultivable actinobacteria for biotechnological purposes

A total of 118 actinobacterial isolates were collected from the three types of termite nests (mound, carton, and subterranean nests) to evaluate their potential as a source of bioactive actinobacteria with antimicrobial activity. The highest number (67 isolates) and generic abundance (7 known genera) of actinobacterial isolates were obtained from carton nests. Streptomyces was the dominant genus in each type of termite nest. In the non-Streptomyces group, Nocardia was the dominant genus detected in mound and carton nests, while Pseudonocardia was the dominant genus in subterranean nests. A discovery trend of novel species (<99% similarity in the 16S rRNA gene sequence) was also observed in the termite nests examined. Each type of termite nest housed >20% of bioactive actinobacteria that could inhibit the growth of at least one test organism, while 12 isolates, belonging to the genera Streptomyces, Amycolatopsis, Pseudonocardia, Micromonospora and Nocardia, exhibited distinct antimicrobial activities. Streptomyces sp. CMU-NKS-3 was the most distinct bioactive isolate. It was closely related to S. padanus MITKK-103T, which was confirmed by 99% similarities in their 16S rRNA gene sequences. The highest level of extracellular antimicrobial substances was produced by the isolate CMU-NKS-3, which was grown in potato dextrose broth and exhibited a wide range (6.10×10−4–1.25 mg mL−1) of minimum inhibitory concentrations against diverse pathogens. We concluded that termite nests are an abundant source of bioactive strains of cultivable actinobacteria for future biotechnological needs

Transcriptome and translatome profiles of Streptomyces species in different growth phases.

Streptomyces are efficient producers of various bioactive compounds, which are mostly synthesized by their secondary metabolite biosynthetic gene clusters (smBGCs). The smBGCs are tightly controlled by complex regulatory systems at transcriptional and translational levels to effectively utilize precursors that are supplied by primary metabolism. Thus, dynamic changes in gene expression in response to cellular status at both the transcriptional and translational levels should be elucidated to directly reflect protein levels, rapid downstream responses, and cellular energy costs. In this study, RNA-Seq and ribosome profiling were performed for five industrially important Streptomyces species at different growth phases, for the deep sequencing of total mRNA, and only those mRNA fragments that are protected by translating ribosomes, respectively. Herein, 12.0 to 763.8 million raw reads were sufficiently obtained with high quality of more than 80% for the Phred score Q30 and high reproducibility. These data provide a comprehensive understanding of the transcriptional and translational landscape across the Streptomyces species and contribute to facilitating the rational engineering of secondary metabolite production

SapB and the rodlins are required for development of Streptomyces coelicolor in high osmolarity media

Streptomyces coelicolor produces spore-forming aerial hyphae after a period of vegetative growth. These aerial structures are decorated with a hydrophobic coating of rodlets consisting of chaplins and rodlins. Here, we show that rodlins and the surface-active peptide SapB are essential for development during growth in a medium with high osmolarity. To this end, both vegetative and aerial hyphae secrete SapB, whereas rodlins are only secreted by the spore-forming aerial hyphae.