Multiparametric Sensing of Outer Membrane Vesicle-Derived Supported Lipid Bilayers Demonstrates the Specificity of Bacteriophage Interactions.

The use of bacteriophages, viruses that specifically infect bacteria, as antibiotics has become an area of great interest in recent years as the effectiveness of conventional antibiotics recedes. The detection of phage interactions with specific bacteria in a rapid and quantitative way is key for identifying phages of interest for novel antimicrobials. Outer membrane vesicles (OMVs) derived from Gram-negative bacteria can be used to make supported lipid bilayers (SLBs) and therefore membrane models that contain naturally occurring components of the bacterial outer membrane.

Biosynthesis of Antifungal Solanimycin May Involve an Iterative Nonribosomal Peptide Synthetase Module.

, a plant-pathogenic bacterium, produces solanimycin, a potent hybrid polyketide/nonribosomal peptide (PKS/NRPS) anti-fungal compound. The biosynthetic gene cluster responsible for synthesis of this compound has been identified. Because of instability, the complete structure of the compound has not yet been elucidated, but LC-MS identified that the cluster produces two main compounds, solanimycin A and B, differing by a single hydroxyl group.

Solanimycin: Biosynthesis and Distribution of a New Antifungal Antibiotic Regulated by Two Quorum-Sensing Systems.

The increasing emergence of drug-resistant fungal infections has necessitated a search for new compounds capable of combating fungal pathogens of plants, animals, and humans. Microorganisms represent the main source of antibiotics with applicability in agriculture and in the clinic, but many aspects of their metabolic potential remain to be explored. This report describes the discovery and characterization of a new antifungal compound, solanimycin, produced by a hybrid polyketide/nonribosomal peptide (PKS/NRPS) system in Dickeya solani, the enterobacterial pathogen of potato.

Revision in the first steps of the biosynthesis of the red antibiotic prodigiosin: use of a synthetic thioester to validate a new intermediate.

A biosynthetic pathway for the red-antibiotic, prodigiosin, was proposed over a decade ago but not all the suggested intermediates could be detected experimentally. Here we show that a thioester that was not originally included in the pathway is an intermediate. In addition, the enzyme PigE was originally described as a transaminase but we present evidence that it also catalyses the reduction of the thioester intermediate to its aldehyde substrate.

Ambigols from the Cyanobacterium Increase Prodigiosin Production in spp.

When a library of 573 cyanobacteria extracts was screened for inhibition of the quorum sensing regulated prodigiosin production of , an extract of the cyanobacterium (Näg.) Gomont 108b was found to drastically increase prodigiosin production. Bioactivity-guided isolation of the active compounds resulted in the two new natural products ambigol D and E along with the known ambigols A and C.

The FloR master regulator controls flotation, virulence and antibiotic production in Serratia sp. ATCC 39006.

Serratia sp. ATCC 39006 produces intracellular gas vesicles to enable upward flotation in water columns. It also uses flagellar rotation to swim through liquid and swarm across semi-solid surfaces.

Substrate Flexibility of the Flavin-Dependent Dihydropyrrole Oxidases PigB and HapB Involved in Antibiotic Prodigiosin Biosynthesis.

In the biosynthesis of the tripyrrolic pigment prodigiosin, PigB is a predicted flavin-dependent oxidase responsible for the formation of 2-methyl-3-amylpyrrole (MAP) from a dihydropyrrole. To prove which dihydropyrrole is the true intermediate, both possibilities, 5-methyl-4-pentyl-3,4-dihydro-2H-pyrrole (5 a, resulting from transamination of the aldehyde of 3-acetyloctanal) and 2-methyl-3-pentyl-3,4-dihydro-2H-pyrrole (6, resulting from transamination of the ketone), were synthesised. Only 5 a restored pigment production in a strain of Serratia sp.

Environmental potassium regulates bacterial flotation, antibiotic production and turgor pressure in Serratia through the TrkH transporter.

Serratia sp. strain ATCC 39006 (S39006) can float in aqueous environments due to natural production of gas vesicles (GVs). Expression of genes for GV morphogenesis is stimulated in low oxygen conditions, thereby enabling migration to the air-liquid interface.

The rsmS (ybaM) mutation causes bypass suppression of the RsmAB post-transcriptional virulence regulation system in enterobacterial phytopathogens.

Plant cell wall degrading enzymes (PCWDEs) are the primary virulence determinants of soft rotting bacteria such as the potato pathogen, Pectobacterium atrosepticum. The regulation of secondary metabolite (Rsm) system controls production of PCWDEs in response to changing nutrient conditions. This work identified a new suppressor of an rsmB mutation - ECA1172 or rsmS (rsmB suppressor).

Draft Genome Sequence of Pectobacterium carotovorum subsp. carotovorum ATCC 39048, a Carbapenem-Producing Phytopathogen.

Pectobacterium carotovorum subsp. carotovorum ATCC 39048 was originally isolated in the 1980s and studied because it produced the β-lactam antibiotic 1-carbapen-2-em-3-carboxylic acid. The draft genome for this strain was 4,637,928 bp with a G+C content of 51.

The LacI-Family Transcription Factor, RbsR, Is a Pleiotropic Regulator of Motility, Virulence, Siderophore and Antibiotic Production, Gas Vesicle Morphogenesis and Flotation in .

Gas vesicles (GVs) are proteinaceous, gas-filled organelles used by some bacteria to enable upward movement into favorable air/liquid interfaces in aquatic environments. sp. ATCC39006 (S39006) was the first enterobacterium discovered to produce GVs naturally.

Draft Genome Sequences of Strains CAPREx E7 and CAPREx E2-2.

strains CAPREx E7 and CAPREx E2-2 were isolated from Ghanaian yams at a London market. The draft genome sequences indicate that the two strains are similar, with genomes of 5,042,838 and 5,039,930 bp and 56.19% and 55.

Draft Genome Sequences of Strains CAPREx SY13 and CAPREx SY21 Isolated from Yams.

strains CAPREx SY13 and CAPREx SY21 were isolated from Ghanaian yams from a London market. The draft genomes suggest that the strains are similar, with genomes of 5,308,004 and 5,157,134 bp and 59.35 and 59.

Overproduction of individual gas vesicle proteins perturbs flotation, antibiotic production and cell division in the enterobacterium Serratia sp. ATCC 39006.

Gas vesicles are intracellular proteinaceous organelles that facilitate bacterial colonization of static water columns. In the enterobacterium Serratia sp. ATCC 39006, gas vesicle formation requires the proteins GvpA1, GvpF1, GvpG, GvpA2, GvpK, GvpA3, GvpF2 and GvpF3 and the three gas vesicle regulatory proteins GvrA, GvrB and GvrC.

Molecular genetic and physical analysis of gas vesicles in buoyant enterobacteria.

Different modes of bacterial taxis play important roles in environmental adaptation, survival, colonization and dissemination of disease. One mode of taxis is flotation due to the production of gas vesicles. Gas vesicles are proteinaceous intracellular organelles, permeable only to gas, that enable flotation in aquatic niches.

A Plasmid-Transposon Hybrid Mutagenesis System Effective in a Broad Range of Enterobacteria.

Random transposon mutagenesis is a powerful technique used to generate libraries of genetic insertions in many different bacterial strains. Here we develop a system facilitating random transposon mutagenesis in a range of different Gram-negative bacterial strains, including Pectobacterium atrosepticum, Citrobacter rodentium, Serratia sp. ATCC39006, Serratia plymuthica, Dickeya dadantii, and many more.

A Type III protein-RNA toxin-antitoxin system from Bacillus thuringiensis promotes plasmid retention during spore development.

Members of the Bacillus cereus sensu lato group of bacteria often contain multiple large plasmids, including those encoding virulence factors in B. anthracis. Bacillus species can develop into spores in response to stress.

Draft Genome Sequence of Serratia sp. Strain ATCC 39006, a Model Bacterium for Analysis of the Biosynthesis and Regulation of Prodigiosin, a Carbapenem, and Gas Vesicles.

Serratia sp. strain ATCC 39006 is a Gram-negative bacterium and a member of the Enterobacteriaceae that produces various bioactive secondary metabolites, including the tripyrrole red pigment prodigiosin and the β-lactam antibiotic 1-carbapenen-2-em-3-carboxylic acid (a carbapenem). This strain is the only member of the Enterobacteriaceae known to naturally produce gas vesicles, as flotation organelles.

Virulence in Pectobacterium atrosepticum is regulated by a coincidence circuit involving quorum sensing and the stress alarmone, (p)ppGpp.

Pectobacterium atrosepticum (Pca) is a Gram-negative phytopathogen which causes disease by secreting plant cell wall degrading exoenzymes (PCWDEs). Previous studies have shown that PCWDE production is regulated by (i) the intercellular quorum sensing (QS) signal molecule, 3-oxo-hexanoyl-l-homoserine lactone (OHHL), and (ii) the intracellular 'alarmone', (p)ppGpp, which reports on nutrient limitation. Here we show that these two signals form an integrated coincidence circuit which ensures that metabolically costly PCWDE synthesis does not occur unless the population is simultaneously quorate and nutrient limited.

Genome sequence of a new Streptomyces coelicolor generalized transducing bacteriophage, ΦCAM.

Streptomyces coelicolor is a model system for the study of Streptomyces, a genus of bacteria responsible for the production of many clinically important antibiotics. Here we report the genome sequence of ΦCAM, a new S. coelicolor generalized transducing bacteriophage, isolated from a soil sample originating from Lincolnshire, United Kingdom.

Identification of genes in the VirR regulon of Pectobacterium atrosepticum and characterization of their roles in quorum sensing-dependent virulence.

In the economically important phytopathogen, Pectobacterium atrosepticum, expression of plant cell wall degrading enzymes and other virulence determinants is controlled in a cell density-dependent fashion, termed quorum sensing (QS). Canonical QS systems in Gram-negative bacteria contain a LuxI-type protein, synthesizing a signalling molecule, and a LuxR-type regulator, responding to the signalling molecule above threshold concentrations. In P.

Citrobacter rodentium is an unstable pathogen showing evidence of significant genomic flux.

Citrobacter rodentium is a natural mouse pathogen that causes attaching and effacing (A/E) lesions. It shares a common virulence strategy with the clinically significant human A/E pathogens enteropathogenic E. coli (EPEC) and enterohaemorrhagic E.

The Pseudomonas aeruginosa generalized transducing phage phiPA3 is a new member of the phiKZ-like group of 'jumbo' phages, and infects model laboratory strains and clinical isolates from cystic fibrosis patients.

Pseudomonas aeruginosa is an important pathogen in cystic fibrosis patients, and a model organism for the study of nosocomially acquired infections, biofilms and intrinsic multidrug resistance. In this study we characterize ϕPA3, a new generalized transducing bacteriophage for P. aeruginosa.

Identification and characterization of int (integrase), xis (excisionase) and chromosomal attachment sites of the integrative and conjugative element ICEBs1 of Bacillus subtilis.

ICEBs1 is an integrative and conjugative element (conjugative transposon) integrated into trnS-leu2 in Bacillus subtilis. In response to DNA damage or high concentrations of potential mating partners, ICEBs1 can excise and transfer to various recipients, including other species. We found that excision of ICEBs1 occurs by site-specific recombination within 60 bp direct repeats that mark the junctions between ICEBs1 and chromosomal DNA.