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Molecular Microbiology Dec 2011Many bacteria are now believed to produce small signal molecules in order to communicate in a process called quorum sensing (QS), which mediates cooperative traits and a... (Review)
Review
Many bacteria are now believed to produce small signal molecules in order to communicate in a process called quorum sensing (QS), which mediates cooperative traits and a co-ordinated behaviour. Pseudomonads have been extensively studied for their QS response highlighting that it plays a major role in determining their lifestyle. The main QS signal molecules produced by Pseudomonas belong to the family of N-acyl-homoserine lactones (AHLs); these are synthesized by a LuxI-family synthase and sensed by a LuxR-family regulator. Most often in Pseudomonas, repressor genes intergenically located between luxI and luxR form an integral part of QS system. Recent studies have highlighted an important role of these repressors (called RsaL and RsaM) in containing the QS response within cost-effective levels; this is central for pseudomonads as they have very versatile genomes allowing them to live in constantly changing and highly dynamic environments. This review focuses on the role played by RsaL and RsaM repressors and discusses the important implications of this control of the QS response.
Topics: Acyl-Butyrolactones; Gene Expression Regulation, Bacterial; Pseudomonas; Quorum Sensing; Repressor Proteins; Signal Transduction
PubMed: 22060261
DOI: 10.1111/j.1365-2958.2011.07890.x -
Applied and Environmental Microbiology Jan 2016The Pseudomonas genus contains a metabolically versatile group of organisms that are known to occupy numerous ecological niches, including the rhizosphere and endosphere...
The Pseudomonas genus contains a metabolically versatile group of organisms that are known to occupy numerous ecological niches, including the rhizosphere and endosphere of many plants. Their diversity influences the phylogenetic diversity and heterogeneity of these communities. On the basis of average amino acid identity, comparative genome analysis of >1,000 Pseudomonas genomes, including 21 Pseudomonas strains isolated from the roots of native Populus deltoides (eastern cottonwood) trees resulted in consistent and robust genomic clusters with phylogenetic homogeneity. All Pseudomonas aeruginosa genomes clustered together, and these were clearly distinct from other Pseudomonas species groups on the basis of pangenome and core genome analyses. In contrast, the genomes of Pseudomonas fluorescens were organized into 20 distinct genomic clusters, representing enormous diversity and heterogeneity. Most of our 21 Populus-associated isolates formed three distinct subgroups within the major P. fluorescens group, supported by pathway profile analysis, while two isolates were more closely related to Pseudomonas chlororaphis and Pseudomonas putida. Genes specific to Populus-associated subgroups were identified. Genes specific to subgroup 1 include several sensory systems that act in two-component signal transduction, a TonB-dependent receptor, and a phosphorelay sensor. Genes specific to subgroup 2 contain hypothetical genes, and genes specific to subgroup 3 were annotated with hydrolase activity. This study justifies the need to sequence multiple isolates, especially from P. fluorescens, which displays the most genetic variation, in order to study functional capabilities from a pangenomic perspective. This information will prove useful when choosing Pseudomonas strains for use to promote growth and increase disease resistance in plants.
Topics: Comparative Genomic Hybridization; Genetic Variation; Genome, Bacterial; Phylogeny; Plant Roots; Populus; Pseudomonas; Pseudomonas aeruginosa; Pseudomonas fluorescens; Pseudomonas putida; Rhizosphere; Sequence Analysis, DNA
PubMed: 26519390
DOI: 10.1128/AEM.02612-15 -
Applied and Environmental Microbiology Jun 1989
Review
Topics: Gene Expression Regulation; Genes, Bacterial; Models, Genetic; Plasmids; Pseudomonas; Toluene
PubMed: 2669630
DOI: 10.1128/aem.55.6.1323-1328.1989 -
Applied and Environmental Microbiology May 1993Two Pseudomonas isolates, named ES-1 and ES-2, were shown to possess a wide degradative spectrum for haloalkanes in general and bromoalkanes in particular but did not...
Two Pseudomonas isolates, named ES-1 and ES-2, were shown to possess a wide degradative spectrum for haloalkanes in general and bromoalkanes in particular but did not degrade nonsubstituted alkanes. The utilization of water-insoluble haloalkanes, such as 1-bromooctane, appeared to consist of three phases: (i) extracellular emulsification by a constitutively excreted, broad-spectrum surface-active agent, (ii) dehalogenation by an inducible hydrolytic dehalogenase (possibly periplasmic), and (iii) intracellular degradation of the residual carbon skeleton. Several observations suggest the existence of more than one dehalogenase in strain ES-2.
Topics: Alkanes; Biodegradation, Environmental; Excipients; Hydrocarbons, Brominated; Pseudomonas
PubMed: 8517736
DOI: 10.1128/aem.59.5.1403-1409.1993 -
Journal of Clinical Microbiology May 1981An elderly male patient with Pseudomonas denitrificans bacteremia and meningitis is described. The antimicrobial susceptibility and minimum criteria necessary for the...
An elderly male patient with Pseudomonas denitrificans bacteremia and meningitis is described. The antimicrobial susceptibility and minimum criteria necessary for the identification of this unusual and rare human pathogen are discussed.
Topics: Anti-Bacterial Agents; Blood; Cerebrospinal Fluid; Drug Resistance, Microbial; Humans; Male; Meningitis; Middle Aged; Pseudomonas; Pseudomonas Infections; Sepsis
PubMed: 7240392
DOI: 10.1128/jcm.13.5.1004-1006.1981 -
Microbiology Spectrum Dec 2023The genus contains many members currently being investigated for applications in biodegradation, biopesticides, biocontrol, and synthetic biology. Though several...
The genus contains many members currently being investigated for applications in biodegradation, biopesticides, biocontrol, and synthetic biology. Though several strains have been identified with beneficial properties, chromosomal manipulations to further improve these strains for commercial applications have been limited due to the lack of efficient genetic tools that have been tested across this genus. Here, we test the recombineering efficiencies of five phage-derived recombinases across three biotechnologically relevant strains: KT2440, Pf-5, and CHA0. These results demonstrate a method to generate targeted mutations quickly and efficiently across these strains, ideally introducing a method that can be implemented across the genus and a strategy that may be applied to develop analogous systems in other nonmodel bacteria.
Topics: Pseudomonas; Recombinases; Bacteriophages
PubMed: 37882574
DOI: 10.1128/spectrum.03176-23 -
Research in Microbiology Oct 2014Pseudomonas bacteria are ubiquitous Gram-negative and aerobic microorganisms that are known to harbor metal resistance mechanisms such as efflux pumps and intracellular...
Pseudomonas bacteria are ubiquitous Gram-negative and aerobic microorganisms that are known to harbor metal resistance mechanisms such as efflux pumps and intracellular redox enzymes. Specific Pseudomonas bacteria have been quantified in some metal-contaminated environments, but the entire Pseudomonas population has been poorly investigated under these conditions, and the link with metal bioavailability was not previously examined. In the present study, quantitative PCR and cell cultivation were used to monitor and characterize the Pseudomonas population at 4 different sediment sites contaminated with various levels of metals. At the same time, total metals and metal bioavailability (as estimated using an HCl 1 m extraction) were measured. It was found that the total level of Pseudomonas, as determined by qPCR using two different genes (oprI and the 16S rRNA gene), was positively and significantly correlated with total and HCl-extractable Cu, Co, Ni, Pb and Zn, with high correlation coefficients (>0.8). Metal-contaminated sediments featured isolates of the Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas lutea and Pseudomonas aeruginosa groups, with other bacterial genera such as Mycobacterium, Klebsiella and Methylobacterium. It is concluded that Pseudomonas bacteria do proliferate in metal-contaminated sediments, but are still part of a complex community.
Topics: Biological Availability; Biota; DNA, Bacterial; DNA, Ribosomal; Geologic Sediments; Metals; Molecular Sequence Data; Pseudomonas; RNA, Ribosomal, 16S; Real-Time Polymerase Chain Reaction; Sequence Analysis, DNA
PubMed: 25102022
DOI: 10.1016/j.resmic.2014.07.011 -
Food Microbiology Aug 2018Microbiological, chemical and physical parameters of minimally processed red chicory (Cichorium intybus L.) subjected to two different transformation processes were...
Microbiological, chemical and physical parameters of minimally processed red chicory (Cichorium intybus L.) subjected to two different transformation processes were investigated. A classic ready-to-eat (RTE) process (P1) and a production without cutting (P2) were monitored during refrigerated (4 °C) storage (15 d). Total mesophilic microorganisms, total psychrotrophic microorganisms and pseudomonads were detected at the highest cell densities in all samples. Presumptive Pseudomonas population dominated the cultivable microbial community of RTE red chicory and were characterized genetically. Twenty-two randomly amplified polymorphic DNA (RAPD) types were investigated by 16S rRNA gene sequencing, resulting in members of Rahnella and Pseudomonas. The identification of Pseudomonas species was further determined by sequencing of gyrB, rpoB and rpoD genes resulting in 16 species. A highest visual quality and a lower weight loss and colour variation were registered for P2, while soluble solid, nitrate and ascorbic acid contents were not affected by processing and storage. The integrated microbiological, chemical and physical approach applied in this study demonstrated the longer shelf-life of P2 red chicory.
Topics: Cichorium intybus; Food Storage; Pseudomonas; Random Amplified Polymorphic DNA Technique; Vegetables
PubMed: 29526216
DOI: 10.1016/j.fm.2018.02.008 -
Diagnostic Microbiology and Infectious... Mar 2021The NitroSpeed-Carba NP test was used to rapidly detect and discriminate between the different types of carbapenemases (classes A, B, and D) within 30 minutes among a...
The NitroSpeed-Carba NP test was used to rapidly detect and discriminate between the different types of carbapenemases (classes A, B, and D) within 30 minutes among a collection of 202 Pseudomonas sp. strains (mostly Pseudomonas aeruginosa). A total of 99 carbapenemase-(including enzymes exhibiting weak carbapenemase activity such as several Guyana Extended-Spectrum (GES)-ß-lactamases) and 103 non-carbapenemase producers were tested, and the overall specificity and sensitivity were 100% and 99%, respectively. The NitroSpeed-Carba NP test is a rapid, specific, sensitive, and easy-to-implement technique for identification of carbapenemase-producing Pseudomonas spp.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Bacteriological Techniques; Humans; Microbial Sensitivity Tests; Pseudomonas; Pseudomonas Infections; Reagent Kits, Diagnostic; Sensitivity and Specificity; beta-Lactamases
PubMed: 33321426
DOI: 10.1016/j.diagmicrobio.2020.115280 -
Molecular Plant Pathology Dec 2012Pseudomonas savastanoi pv. savastanoi is the causal agent of olive (Olea europaea) knot disease and an unorthodox member of the P. syringae complex, causing aerial... (Review)
Review
UNLABELLED
Pseudomonas savastanoi pv. savastanoi is the causal agent of olive (Olea europaea) knot disease and an unorthodox member of the P. syringae complex, causing aerial tumours instead of the foliar necroses and cankers characteristic of most members of this complex. Olive knot is present wherever olive is grown; although losses are difficult to assess, it is assumed that olive knot is one of the most important diseases of the olive crop. The last century witnessed a large number of scientific articles describing the biology, epidemiology and control of this pathogen. However, most P. savastanoi pv. savastanoi strains are highly recalcitrant to genetic manipulation, which has effectively prevented the pathogen from benefitting from the scientific progress in molecular biology that has elevated the foliar pathogens of the P. syringae complex to supermodels. A number of studies in recent years have made significant advances in the biology, ecology and genetics of P. savastanoi pv. savastanoi, paving the way for the molecular dissection of its interaction with other nonpathogenic bacteria and their woody hosts. The selection of a genetically pliable model strain was soon followed by the development of rapid methods for virulence assessment with micropropagated olive plants and the analysis of cellular interactions with the plant host. The generation of a draft genome of strain NCPPB 3335 and the closed sequence of its three native plasmids has allowed for functional and comparative genomic analyses for the identification of its pathogenicity gene complement. This includes 34 putative type III effector genes and genomic regions, shared with other pathogens of woody hosts, which encode metabolic pathways associated with the degradation of lignin-derived compounds. Now, the time is right to explore the molecular basis of the P. savastanoi pv. savastanoi-olive interaction and to obtain insights into why some pathovars like it necrotic and why some like it knot.
SYNONYMS
Pseudomonas syringae pv. savastanoi.
TAXONOMY
Kingdom Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Family Pseudomonadaceae; Genus Pseudomonas; included in genomospecies 2 together with at least P. amygdali, P. ficuserectae, P. meliae and 16 other pathovars from the P. syringae complex (aesculi, ciccaronei, dendropanacis, eriobotryae, glycinea, hibisci, mellea, mori, myricae, phaseolicola, photiniae, sesami, tabaci, ulmi and certain strains of lachrymans and morsprunorum); when a formal proposal is made for the unification of these bacteria, the species name P. amygdali would take priority over P. savastanoi.
MICROBIOLOGICAL PROPERTIES
Gram-negative rods, 0.4-0.8 × 1.0-3.0 μm, aerobic. Motile by one to four polar flagella, rather slow growing, optimal temperatures for growth of 25-30 °C; oxidase negative, arginine dihydrolase negative; elicits the hypersensitive response on tobacco; most isolates are fluorescent and levan negative, although some isolates are nonfluorescent and levan positive.
HOST RANGE
P. savastanoi pv. savastanoi causes tumours in cultivated and wild olive and ash (Fraxinus excelsior). Although strains from olive have been reported to infect oleander (Nerium oleander), this is generally not the case; however, strains of P. savastanoi pv. nerii can infect olive. Pathovars fraxini and nerii are differentiated from pathovar savastanoi mostly in their host range, and were not formally recognized until 1996. Literature before about 1996 generally names strains of the three pathovars as P. syringae ssp. savastanoi or P. savastanoi ssp. savastanoi, contributing to confusion on the host range and biological properties.
DISEASE SYMPTOMS
Symptoms of infected trees include hyperplastic growths (tumorous galls or knots) on the stems and branches of the host plant and, occasionally, on leaves and fruits.
EPIDEMIOLOGY
The pathogen can survive and multiply on aerial plant surfaces, as well as in knots, from where it can be dispersed by rain, wind, insects and human activities, entering the plant through wounds. Populations are very unevenly distributed in the plant, and suffer drastic fluctuations throughout the year, with maximum numbers of bacteria occurring during rainy and warm months. Populations of P. savastanoi pv. savastanoi are normally associated with nonpathogenic bacteria, both epiphytically and endophytically, and have been demonstrated to form mutualistic consortia with Erwinia toletana and Pantoea agglomerans, which could result in increased bacterial populations and disease symptoms.
DISEASE CONTROL
Based on preventive measures, mostly sanitary and cultural practices. Integrated control programmes benefit from regular applications of copper formulations, which should be maintained for at least a few years for maximum benefit. Olive cultivars vary in their susceptibility to olive knot, but there are no known cultivars with full resistance to the pathogen.
USEFUL WEBSITES
http://www.pseudomonas-syringae.org/; http://genome.ppws.vt.edu/cgi-bin/MLST/home.pl; ASAP access to the P. savastanoi pv. savastanoi NCPPB 3335 genome sequence https://asap.ahabs.wisc.edu/asap/logon.php.
Topics: Adaptation, Physiological; Genome, Bacterial; Host-Pathogen Interactions; Humans; Olea; Plant Diseases; Pseudomonas
PubMed: 22805238
DOI: 10.1111/j.1364-3703.2012.00816.x