Unveiling metabolo-genomic insights of potent antitumoral and antibiotic activity in Streptomyces sp. VB1 from Valparaíso Bay.

Streptomyces sp. VB1, an actinomycete isolated from marine sediments in Valparaíso Bay, Chile, synthesizes antimicrobial and antiproliferative compounds. This study presents comprehensive metabolomics and comparative genomics analyses of strain VB1. LC-HRMS dereplication and Molecular Networking analysis of crude extracts identified antibiotics such as globomycin and daunorubicin, along with known and potentially novel members of the arylomycin family. These compounds exhibit activity against a range of clinically relevant bacterial and cancer cell lines. Phylogenomic analysis underscores the uniqueness of strain VB1, suggesting it represents a novel taxon. Such uniqueness is further supported by its Biosynthetic Novelty Index (BiNI) and BiG-SCAPE analysis of Gene Cluster Families (GCFs). Notably, two Biosynthetic Gene Clusters (BGCs) were found to be unique to VB1 compared to closely related strains: BGC #15, which encodes potentially novel anthracycline compounds with cancer cell growth inhibition properties, and BGC #28, which features a non-canonical configuration combining arylomycin, globomycin, and siamycin BGCs. This supercluster, the first described to consist of more than two adjacent and functional BGCs, co-produces at least three antimicrobial compounds from different antibiotic families. These findings highlight Streptomyces sp. VB1's potential for discovering new bioactive molecules, positioning it as a promising candidate for further research.

Mimicking Nonribosomal Peptides from the Marine Actinomycete Streptomyces sp. H-KF8 Leads to Antimicrobial Peptides.

Microorganisms within the marine environment have been shown to be very effective sources of naturally produced antimicrobial peptides (AMPs). Several nonribosomal peptides were identified based on genome mining predictions of Streptomyces sp. H-KF8, a marine Actinomycetota isolated from a remote Northern Chilean Patagonian fjord. Based on these predictions, a series of eight peptides, including cyclic peptides, were designed and chemically synthesized. Six of these peptides showed antimicrobial activity. Mode of action studies suggest that two of these peptides potentially act on the cell membrane via a novel mechanism allowing the passage of small ions, resulting in the dissipation of the membrane potential. This study shows that though structurally similar peptides, determined by NMR spectroscopy, the incorporation of small sequence mutations results in a dramatic influence on their bioactivity including mode of action. The qualified hit sequence can serve as a basis for more potent AMPs in future studies.

Spiractinospora alimapuensis gen. nov., sp. nov., isolated from marine sediment of Valparaíso Bay (Chile) and proposal for reclassification of two species of the genus Nocardiopsis.

An alkaliphilic actinobacterium, designated VN6-2T, was isolated from marine sediment collected from Valparaíso Bay, Chile. Strain VN6-2T formed yellowish-white branched substrate mycelium without fragmentation. Aerial mycelium was well developed, forming wavy or spiral spore chains. Strain VN6-2T exhibited a 16S rRNA gene sequence similarity of 93.9 % to Salinactinospora qingdaonensis CXB832T, 93.7 % to Murinocardiopsis flavida 14-Be-013T, and 93.7 % to Lipingzhangella halophila 14-Be-013T. Genome sequencing revealed a genome size of 5.9 Mb and an in silico G+C content of 69.3 mol%. Both of the phylogenetic analyses based on 16S rRNA gene sequences and the up-to-date bacterial core gene sequences revealed that strain VN6-2T formed a distinct monophyletic clade within the family Nocardiopsaceae. Chemotaxonomic assessment of strain VN6-2T showed that the major fatty acids were iso-C16 : 0, anteiso-C17 : 0 and 10-methyl-C18 : 0, and the predominant respiratory quinones were MK-9, MK-9(H2) and MK-9(H4). Whole-cell hydrolysates contained meso-diaminopimelic acid as the cell-wall diamino acid, and ribose and xylose as the diagnostic sugars. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, aminophospholipids, glycolipid and phospholipid. Based on the results of this polyphasic study, a novel genus, Spiractinospora gen. nov., is proposed within the family Nocardiopsaceae and the type species Spiractinospora alimapuensis gen. nov., sp. nov. The type strain is VN6-2T (CECT 30026T, CCUG 66258T). On the basis of the phylogenetic results herein, we also propose that Nocardiopsis arvandica and Nocardiopsis litoralis are later heterotypic synonyms of Nocardiopsis sinuspersici and Nocardiopsis kunsanensis, respectively, for which emended descriptions are given.

Biodiversity of Actinobacteria from the South Pacific and the Assessment of Streptomyces Chemical Diversity with Metabolic Profiling.

Recently, bioprospecting in underexplored habitats has gained enhanced focus, since new taxa of marine actinobacteria can be found, and thus possible new metabolites. Actinobacteria are in the foreground due to their versatile production of secondary metabolites that present various biological activities, such as antibacterials, antitumorals and antifungals. Chilean marine ecosystems remain largely unexplored and may represent an important source for the discovery of bioactive compounds. Various culture conditions to enrich the growth of this phylum were used and 232 bacterial strains were isolated. Comparative analysis of the 16S rRNA gene sequences led to identifying genetic affiliations of 32 genera, belonging to 20 families. This study shows a remarkable culturable diversity of actinobacteria, associated to marine environments along Chile. Furthermore, 30 streptomycete strains were studied to establish their antibacterial activities against five model strains, Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica, Escherichia coli and Pseudomonas aeruginosa, demonstrating abilities to inhibit bacterial growth of Gram-positive bacteria. To gain insight into their metabolic profiles, crude extracts were submitted to liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis to assess the selection of streptomycete strains with potentials of producing novel bioactive metabolites. The combined approach allowed for the identification of three streptomycete strains to pursue further investigations. Our Chilean marine actinobacterial culture collection represents an important resource for the bioprospection of novel marine actinomycetes and its metabolites, evidencing their potential as producers of natural bioproducts.

Efeitos da fisioterapia respiratória na bronquiectasia não fibrocística: uma revisão sistemática / Effects of chest physiotherapy in non-cystic fibrosis bronchiectasis: A systematic review

Bronchiectasis is the irreversible dilation and distortion of the bronchi in response to the destruction of the elastic and muscular components of their wall. The objective of this study was to analyze the efficacy of respiratory physiotherapy in patients with noncystic fibrosis bronchiectasis. The literature was reviewed systematically and clinical trials published between 2004 and 2015 in the databases PubMed, SciELO, and LILACS were selected using the keywords "respiratory therapy", "bronchiectasis", and "physiotherapy", in English and in Portuguese. A total of 717 clinical trials were found but only six met the inclusion criteria. Of these, five presented significant results from respiratory physiotherapy techniques and/or resources. According to the literature, the various techniques and resources of respiratory physiotherapy were effective therapeutic options for treating patients with non-cystic fibrosis bronchiectasis.

Culturable diversity and antimicrobial activity of Actinobacteria from marine sediments in Valparaíso bay, Chile.

Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valparaíso bay, Chile, and their potential to produce antibacterial compounds was evaluated. Different culture conditions and selective media that select the growth of Actinobacteria were used leading to the isolation of 68 bacterial strains. Comparative analysis of the 16S rRNA gene sequences led to identifying isolates that belong to the phylum Actinobacteria with genetic affiliations to 17 genera: Aeromicrobium, Agrococcus, Arthrobacter, Brachybacterium, Corynebacterium, Dietzia, Flaviflexus, Gordonia, Isoptericola, Janibacter, Microbacterium, Mycobacterium, Ornithinimicrobium, Pseudonocardia, Rhodococcus, Streptomyces, and Tessaracoccus. Also, one isolate could not be consistently classified and formed a novel phylogenetic branch related to the Nocardiopsaceae family. The antimicrobial activity of these isolates was evaluated, demonstrating the capability of specific novel isolates to inhibit the growth of Gram-positive and Gram-negative bacteria. In conclusion, this study shows a rich biodiversity of culturable Actinobacteria, associated to marine sediments from Valparaíso bay, highlighting novel rare Actinobacteria, and their potential for the production of biologically active compounds.

Coupling sigma factor conformation to RNA polymerase reorganisation for DNA melting.

ATP-driven remodelling of initial RNA polymerase (RNAP) promoter complexes occurs as a major post recruitment strategy used to control gene expression. Using a model-enhancer-dependent bacterial system (sigma54-RNAP, Esigma54) and a slowly hydrolysed ATP analogue (ATPgammaS), we provide evidence for a nucleotide-dependent temporal pathway leading to DNA melting involving a small set of sigma54-DNA conformational states. We demonstrate that the ATP hydrolysis-dependent remodelling of Esigma54 occurs in at least two distinct temporal steps. The first detected remodelling phase results in changes in the interactions between the promoter specificity sigma54 factor and the promoter DNA. The second detected remodelling phase causes changes in the relationship between the promoter DNA and the core RNAP catalytic beta/beta' subunits, correlating with the loading of template DNA into the catalytic cleft of RNAP. It would appear that, for Esigma54 promoters, loading of template DNA within the catalytic cleft of RNAP is dependent on fast ATP hydrolysis steps that trigger changes in the beta' jaw domain, thereby allowing acquisition of the open complex status.

Response to (chloro)biphenyls of the polychlorobiphenyl-degrader Burkholderia xenovorans LB400 involves stress proteins also induced by heat shock and oxidative stress.

We report the effects of 4-chlorobiphenyl and biphenyl on the physiology, morphology and proteome of the polychlorobiphenyl-degrader Burkholderia xenovorans LB400. The exposure to 4-chlorobiphenyl decreases the growth of LB400 on glucose, and cells exhibit irregular outer membranes, a larger periplasmic space and electron-dense granules in the cytoplasm. Additionally, lysis of cells was observed during incubation with 4-chlorobiphenyl or biphenyl. Proteome of B. xenovorans LB400 exposed to biphenyl and 4-chlorobiphenyl were analysed by two-dimensional gel electrophoresis. Besides induction of the Bph enzymes of biphenyl catabolic pathways, incubation with 4-chlorobiphenyl or biphenyl results in the induction of the molecular chaperones DnaK and GroEL. Induction of these chaperones, which were also induced during heat shock, strongly suggests that exposure to (chloro)biphenyls constitutes stress conditions for LB400. During growth of LB400 on biphenyl, oxidative stress was evidenced by the induction of alkyl hydroperoxide reductase AhpC, which was also induced during exposure to H(2)O(2). 4-chlorobiphenyl and biphenyl induced catechol 1,2-dioxygenase, as well as polypeptides involved in energy production, amino acid metabolism and transport.