The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Dianne K Newman - One of the best experts on this subject based on the ideXlab platform.
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global landscape of Phenazine biosynthesis and biodegradation reveals species specific colonization patterns in agricultural soils and crop microbiomes
eLife, 2020Co-Authors: Daniel Dar, Linda S Thomashow, David M Weller, Dianne K NewmanAbstract:Phenazines are natural bacterial antibiotics that can protect crops from disease. However, for most crops it is unknown which producers and specific Phenazines are ecologically relevant, and whether Phenazine biodegradation can counter their effects. To better understand their ecology, we developed and environmentally-validated a quantitative metagenomic approach to mine for Phenazine biosynthesis and biodegradation genes, applying it to >800 soil and plant-associated shotgun-metagenomes. We discover novel producer-crop associations and demonstrate that Phenazine biosynthesis is prevalent across habitats and preferentially enriched in rhizospheres, whereas biodegrading bacteria are rare. We validate an association between maize and Dyella japonica, a putative producer abundant in crop microbiomes. D. japonica upregulates Phenazine biosynthesis during phosphate limitation and robustly colonizes maize seedling roots. This work provides a global picture of Phenazines in natural environments and highlights plant-microbe associations of agricultural potential. Our metagenomic approach may be extended to other metabolites and functional traits in diverse ecosystems.
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enzymatic degradation of Phenazines can generate energy and protect sensitive organisms from toxicity
Mbio, 2015Co-Authors: Kyle C Costa, Megan Bergkessel, Scott Saunders, Jonas Korlach, Dianne K NewmanAbstract:Diverse bacteria, including several Pseudomonas species, produce a class of redox-active metabolites called Phenazines that impact different cell types in nature and disease. Phenazines can affect microbial communities in both positive and negative ways, where their presence is correlated with decreased species richness and diversity. However, little is known about how the concentration of Phenazines is modulated in situ and what this may mean for the fitness of members of the community. Through culturing of Phenazine-degrading mycobacteria, genome sequencing, comparative genomics, and molecular analysis, we identified several conserved genes that are important for the degradation of three Pseudomonas-derived Phenazines: Phenazine-1-carboxylic acid (PCA), Phenazine-1-carboxamide (PCN), and pyocyanin (PYO). PCA can be used as the sole carbon source for growth by these organisms. Deletion of several genes in Mycobacterium fortuitum abolishes the degradation phenotype, and expression of two genes in a heterologous host confers the ability to degrade PCN and PYO. In cocultures with Phenazine producers, Phenazine degraders alter the abundance of different Phenazine types. Not only does degradation support mycobacterial catabolism, but also it provides protection to bacteria that would otherwise be inhibited by the toxicity of PYO. Collectively, these results serve as a reminder that microbial metabolites can be actively modified and degraded and that these turnover processes must be considered when the fate and impact of such compounds in any environment are being assessed.
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Phenazine redox cycling enhances anaerobic survival in pseudomonas aeruginosa by facilitating generation of atp and a proton motive force
Molecular Microbiology, 2014Co-Authors: Nathaniel R Glasser, Suzanne E Kern, Dianne K NewmanAbstract:While many studies have explored the growth of Pseudomonas aeruginosa, comparatively few have focused on its survival. Previously, we reported that endogenous Phenazines support the anaerobic survival of P. aeruginosa, yet the physiological mechanism underpinning survival was unknown. Here, we demonstrate that Phenazine redox cycling enables P. aeruginosa to oxidize glucose and pyruvate into acetate, which promotes survival by coupling acetate and ATP synthesis through the activity of acetate kinase. By measuring intracellular NAD(H) and ATP concentrations, we show that survival is correlated with ATP synthesis, which is tightly coupled to redox homeostasis during pyruvate fermentation but not during arginine fermentation. We also show that ATP hydrolysis is required to generate a proton-motive force using the ATP synthase complex during fermentation. Together, our results suggest that Phenazines enable maintenance of the proton-motive force by promoting redox homeostasis and ATP synthesis. This work demonstrates the more general principle that extracellular redox-active molecules, such as Phenazines, can broaden the metabolic versatility of microorganisms by facilitating energy generation.
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Phenazine content in the cystic fibrosis respiratory tract negatively correlates with lung function and microbial complexity
American Journal of Respiratory Cell and Molecular Biology, 2012Co-Authors: Ryan C Hunter, Dianne K Newman, Vanja Klepacceraj, Magen M Lorenzi, Hannah Grotzinger, Thomas R MartinAbstract:Although much is known about how virulence factors affect pathogens and host tissues in vitro, far less is understood about their dynamics in vivo. As a step toward characterizing the chemistry of infected environments, we measured Phenazine abundance in the lungs of patients with cystic fibrosis (CF). Phenazines are redox-active small molecules produced by Pseudomonas aeruginosa that damage host epithelia, curb the growth of competing organisms, and play physiologically important roles in the cells that produce them. Here, we quantify Phenazines within expectorated sputum, characterize the P. aeruginosa populations responsible for Phenazine production, and assess their relationship to CF lung microflora. Chemical analyses of expectorated sputum showed that the concentrations of two Phenazines, namely, pyocyanin (PYO) and Phenazine-1–carboxylic acid (PCA), were negatively correlated (ρ = −0.68 and −0.57, respectively) with lung function. Furthermore, the highest Phenazine concentrations were found in patients whose pulmonary function showed the greatest rates of decline. The constituent P. aeruginosa populations within each patient showed diverse capacities for Phenazine production. Early during infection, individual isolates produced more PYO than later during infection. However, total PYO concentrations in sputum at any given stage correlated well with the average production by the total P. aeruginosa population. Finally, bacterial community complexity was negatively correlated with Phenazine concentrations and declines in lung function, suggesting a link to the refinement of the overall microbial population. Together, these data demonstrate that Phenazines negatively correlate with CF disease states in ways that were previously unknown, and underscore the importance of defining in vivo environmental parameters to better predict clinical outcomes of infections.
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endogenous Phenazine antibiotics promote anaerobic survival of pseudomonas aeruginosa via extracellular electron transfer
Journal of Bacteriology, 2010Co-Authors: Dianne K Newman, Yun Wang, Suzanne E KernAbstract:Antibiotics are increasingly recognized as having other, important physiological functions for the cells that produce them. An example of this is the effect that Phenazines have on signaling and community development for Pseudomonas aeruginosa (L. E. Dietrich, T. K. Teal, A. Price-Whelan, and D. K. Newman, Science 321:1203-1206, 2008). Here we show that Phenazine-facilitated electron transfer to poised-potential electrodes promotes anaerobic survival but not growth of Pseudomonas aeruginosa PA14 under conditions of oxidant limitation. Other electron shuttles that are reduced but not made by PA14 do not facilitate survival, suggesting that the survival effect is specific to endogenous Phenazines.
Xuehong Zhang - One of the best experts on this subject based on the ideXlab platform.
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identification of a novel bioactive Phenazine derivative and regulation of phop on its production in streptomyces lomondensis s015
Journal of Agricultural and Food Chemistry, 2021Co-Authors: Ruxiang Deng, Wei Wang, Zhuo Zhang, Xuehong ZhangAbstract:Natural Phenazines are a class of multifunctional secondary metabolites of bacteria that play an important role in the biocontrol of plant pathogens. In this paper, a novel bioactive Phenazine derivative was isolated from Streptomyces lomondensis S015 through silica gel chromatography and preparative high-performance liquid chromatography (HPLC). The structure was identified as 1-carboxyl-6-formyl-4,7,9-trihydroxy-Phenazine (CFTHP) by NMR spectroscopy in combination with ultraperformance liquid chromatography & mass spectrometry (UPLC-MS). CFTHP could inhibit Pythium ultimum, Rhizoctonia solani, Septoria steviae, and Fusarium oxysporum f. sp. niveum with minimal inhibitory concentration (MIC) values of 16, 32, 16, and 16 μg/mL, respectively. A global regulatory gene phoP could positively regulate CFTHP biosynthesis since its production was 3.0-fold enhanced by phoP overexpression and inhibited by phoP deletion in Streptomyces lomondensis S015. These studies illustrated the potential of CFTHP as a promising biopesticide and provided a reference for Phenazine production improvement.
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designing an artificial pathway for the biosynthesis of a novel Phenazine n oxide in pseudomonas chlororaphis ht66
ACS Synthetic Biology, 2020Co-Authors: Shuqi Guo, Wei Wang, Rongfeng Liu, Xuehong ZhangAbstract:Aromatic N-oxides are valuable due to their versatile chemical, pharmaceutical, and agricultural applications. Natural Phenazine N-oxides possess potent biological activities and can be applied in many ways; however, few N-oxides have been identified. Herein, we developed a microbial system to synthesize Phenazine N-oxides via an artificial pathway. First, the N-monooxygenase NaphzNO1 was predicted and screened in Nocardiopsis sp. 13-12-13 through a product comparison and gene sequencing. Subsequently, according to similarities in the chemical structures of substrates, an artificial pathway for the synthesis of a Phenazine N-oxide in Pseudomonas chlororaphis HT66 was designed and established using three heterologous enzymes, a monooxygenase (PhzS) from P. aeruginosa PAO1, a monooxygenase (PhzO) from P. chlororaphis GP72, and the N-monooxygenase NaphzNO1. A novel Phenazine derivative, 1-hydroxyPhenazine N'10-oxide, was obtained in an engineered strain, P. chlororaphis HT66-SN. The Phenazine N-monooxygenase NaphzNO1 was identified by metabolically engineering the Phenazine-producing platform P. chlororaphis HT66. Moreover, the function of NaphzNO1, which can catalyze the conversion of 1-hydroxyPhenazine but not that of 2-hydroxyPhenazine, was confirmed in vitro. Additionally, 1-hydroxyPhenazine N'10-oxide demonstrated substantial cytotoxic activity against two human cancer cell lines, MCF-7 and HT-29. Furthermore, the highest microbial production of 1-hydroxyPhenazine N'10-oxide to date was achieved at 143.4 mg/L in the metabolically engineered strain P3-SN. These findings demonstrate that P. chlororaphis HT66 has the potential to be engineered as a platform for Phenazine-modifying gene identification and derivative production. The present study also provides a promising alternative for the sustainable synthesis of aromatic N-oxides with unique chemical structures by N-monooxygenase.
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Enhanced biosynthesis of Phenazine-1-carboxamide by engineered Pseudomonas chlororaphis HT66.
Microbial cell factories, 2018Co-Authors: Huasong Peng, Muhammad Bilal, Wei Wang, Zhang Pingyuan, Xuehong ZhangAbstract:Phenazine-1-carboxamide (PCN), a Phenazine derivative, is strongly antagonistic to fungal phytopathogens. The high PCN biocontrol activity fascinated researcher’s attention in isolating and identifying novel bacterial strains combined with engineering strategies to target PCN as a lead molecule. The chemical route for Phenazines biosynthesis employs toxic chemicals and display low productivities, require harsh reaction conditions, and generate toxic by-products. Phenazine biosynthesis using some natural Phenazine-producers represent remarkable advantages of non-toxicity and possibly high yield in environmentally-friendlier settings. A biocontrol bacterium with antagonistic activity towards fungal plant pathogens, designated as strain HT66, was isolated from the rice rhizosphere. The strain HT66 was identified as Pseudomonas chlororaphis based on the colony morphology, gas chromatography of cellular fatty acids and 16S rDNA sequence analysis. The secondary metabolite produced by HT66 strain was purified and identified as PCN through mass spectrometry, and 1H, 13C nuclear magnetic resonance spectrum. The yield of PCN by wild-type strain HT66 was 424.87 mg/L at 24 h. The inactivation of psrA and rpeA increased PCN production by 1.66- and 3.06-fold, respectively, which suggests that psrA and rpeA are PCN biosynthesis repressors. qRT-PCR analysis showed that the expression of phzI, phzR, and phzE was markedly increased in the psrA and rpeA double mutant than in psrA or rpeA mutant. However, the transcription level of rpeA and rpeB in strain HT66ΔpsrA increased by 3.52- and 11.58-folds, respectively. The reduced psrA expression in HT66ΔrpeA strain evidenced a complex regulation mechanism for PCN production in HT66. In conclusion, the results evidence that P. chlororaphis HT66 could be modified as a potential cell factory for industrial-scale biosynthesis of PCN and other Phenazine derivatives by metabolic engineering strategies.
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identification of biphenyl 2 3 dioxygenase and its catabolic role for Phenazine degradation in sphingobium yanoikuyae b1
Journal of Environmental Management, 2017Co-Authors: Qiang Zhao, Muhammad Bilal, Wei Wang, Shengjie Yue, Xuehong ZhangAbstract:Phenazines are important nitrogen-containing secondary metabolites that display a range of biological functionalities. However, these compounds have shown lethal effects on humans and, the fate of Phenazine in the ecosystem remains uncertain. In this study, we investigated that Sphingobium yanoikuyae B1 could utilize Phenazine as a sole carbon source for growth. Intermediate produced during Phenazine degradation was purified and identified as 1, 2-dihydrogen 1, 2-dihydroxy Phenazine. Biphenyl 2, 3-dioxygenase was determined to be the initial dioxygenase for Phenazine degradation through gene cloning and whole cell transformation techniques. Phenazine was converted to 1, 2-dihydrogen 1, 2-dihydroxy Phenazine through hydrogenation and hydroxylation, which then transformed to 2-hydroxy Phenazine through spontaneous dehydration. ThebphA1fA2f, were evidenced to be the only genes encoding the initial dioxygenase for Phenazine degradation. BphB (dihydrodiol dehydrogenase) and BphC (2,3-dihydroxybiphenyl 1,2-dioxygenase) did not exhibit any 1, 2-dihydrogen 1, 2-dihydroxy Phenazine and 1, 2-dihydroxy Phenazine degradation capability, suggesting no contribution in Phenazine degradation. Phylogenetic analysis of the dioxygenases demonstrated enormous biodegradation potential in strain B1. In conclusion, this study opens up new possibilities in better understanding the Phenazine degradation in the environment.
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engineering pseudomonas for Phenazine biosynthesis regulation and biotechnological applications a review
World Journal of Microbiology & Biotechnology, 2017Co-Authors: Muhammad Bilal, Wei Wang, Shuqi Guo, Hafiz M N Iqbal, Xuehong ZhangAbstract:Pseudomonas strains are increasingly attracting considerable attention as a valuable bacterial host both for basic and applied research. It has been considered as a promising candidate to produce a variety of bioactive secondary metabolites, particularly Phenazines. Apart from the biotechnological perspective, these aromatic compounds have the notable potential to inhibit plant-pathogenic fungi and thus are useful in controlling plant diseases. Nevertheless, Phenazines production is quite low by the wild-type strains that necessitated its yield improvement for large-scale agricultural applications. Metabolic engineering approaches with the advent of plentiful information provided by systems-level genomic and transcriptomic analyses enabled the development of new biological agents functioning as potential cell factories for producing the desired level of value-added bioproducts. This study presents an up-to-date overview of recombinant Pseudomonas strains as the preferred choice of host organisms for the biosynthesis of natural Phenazines. The biosynthetic pathway and regulatory mechanism involved in the Phenazine biosynthesis are comprehensively discussed. Finally, a summary of biological functionalities and biotechnological applications of the Phenazines is also provided.
Lars E P Dietrich - One of the best experts on this subject based on the ideXlab platform.
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interdependency of respiratory metabolism and Phenazine associated physiology in pseudomonas aeruginosa pa14
Journal of Bacteriology, 2020Co-Authors: Alexa Pricewhelan, William Cole Cornell, Lars E P DietrichAbstract:Extracellular electron transfer (EET), the reduction of compounds that shuttle electrons to distal oxidants, can support bacterial survival when preferred oxidants are not directly accessible. EET has been shown to contribute to virulence in some pathogenic organisms and is required for current generation in mediator-based fuel cells. In several species, components of the electron transport chain (ETC) have been implicated in electron shuttle reduction, raising the question of how shuttling-based metabolism is integrated with primary routes of metabolic electron flow. The clinically relevant bacterium Pseudomonas aeruginosa can utilize carbon sources (i.e., electron donors) covering a broad range of reducing potentials and possesses a branched ETC that can be modulated to optimize respiratory efficiency. It also produces electron shuttles called Phenazines that facilitate intracellular redox balancing, increasing the complexity of its metabolic potential. In this study, we investigated the reciprocal influence of respiratory metabolism and Phenazine-associated physiology in P. aeruginosa PA14. We found that Phenazine production affects respiratory activity and terminal oxidase gene expression and that carbon source identity influences the mechanisms enabling Phenazine reduction. Furthermore, we found that growth in biofilms, a condition for which Phenazine metabolism is critical to normal development and redox balancing, affects the composition of the P. aeruginosa Phenazine pool. Together, these findings can aid interpretation of P. aeruginosa behavior during host infection and provide inroads to understanding the cross talk between primary metabolism and shuttling-based physiology in the diverse bacteria that carry out EET.IMPORTANCE The clinically relevant pathogen Pseudomonas aeruginosa uses diverse organic compounds as electron donors and possesses multiple enzymes that transfer electrons from central metabolism to O2 These pathways support a balanced intracellular redox state and produce cellular energy. P. aeruginosa also reduces secondary metabolites called Phenazines to promote redox homeostasis and virulence. In this study, we examined the reciprocal relationship between these primary and secondary routes of electron flow. We found that Phenazines affect respiratory function and that the complement of Phenazines produced is strongly affected by growth in assemblages called biofilms. These results provide a more nuanced understanding of P. aeruginosa redox metabolism and may inform strategies for treating persistent infections caused by this bacterium.
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interdependency of respiratory metabolism and Phenazine associated physiology in pseudomonas aeruginosa pa14
bioRxiv, 2019Co-Authors: Alexa Pricewhelan, William Cole Cornell, Lars E P DietrichAbstract:ABSTRACT Extracellular electron transfer (EET), the reduction of compounds that shuttle electrons to distal oxidants, can support bacterial survival when preferred oxidants are not directly accessible. EET has been shown to contribute to virulence in some pathogenic organisms and is required for current generation in mediator-based fuel cells. In several species, components of the electron transport chain (ETC) have been implicated in electron shuttle reduction, raising the question of how shuttling-based metabolism is integrated with primary routes of metabolic electron flow. The clinically relevant bacterium Pseudomonas aeruginosa can utilize carbon sources (i.e., electron donors) covering a broad range of reducing potentials and possesses a branched ETC that can be modulated to optimize respiratory efficiency. It also produces electron shuttles called Phenazines that facilitate intracellular redox balancing, increasing the complexity of its metabolic potential. In this study, we investigated the reciprocal influence of respiratory metabolism and Phenazine-associated physiology in Pseudomonas aeruginosa PA14. We found that Phenazine production affects respiratory activity and terminal oxidase gene expression, and that carbon source identity influences the mechanisms enabling Phenazine reduction. Furthermore, we found that growth in biofilms, a condition for which Phenazine metabolism is critical to normal development and redox balancing, dramatically affects the composition of the P. aeruginosa Phenazine pool. Together, these findings can aid interpretation of P. aeruginosa behavior during host infection and provide inroads to understanding the crosstalk between primary metabolism and shuttling-based physiology in the diverse bacteria that carry out EET. IMPORTANCE Pseudomonas aeruginosa is a major cause of healthcare-associated infections and long-term lung infections in people with cystic fibrosis. It can use diverse organic compounds as electron donors and possesses multiple enzymes that can transfer electrons from central metabolism to O2. These pathways support a balanced intracellular redox state and the production of cellular energy. Under hypoxic conditions, P. aeruginosa can reduce Phenazines, secondary metabolites that also promote redox homeostasis and that contribute to virulence. We asked how these primary and secondary routes of electron flow influence each other. We found that Phenazines affect respiratory function, that the roles of respiratory enzymes in Phenazine reduction are highly condition-dependent, and that the complement of Phenazines produced is strongly affected by growth in assemblages called biofilms. These results provide a more nuanced understanding of P. aeruginosa redox metabolism and may inform strategies for treating persistent infections caused by this bacterium.
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Phenazine production promotes antibiotic tolerance and metabolic heterogeneity in pseudomonas aeruginosa biofilms
Nature Communications, 2019Co-Authors: Konstanze T Schiessl, Alexa Pricewhelan, Sakila Z Nazia, Bryan Wang, Wei Min, Lars E P DietrichAbstract:Antibiotic efficacy can be antagonized by bioactive metabolites and other drugs present at infection sites. Pseudomonas aeruginosa, a common cause of biofilm-based infections, releases metabolites called Phenazines that accept electrons to support cellular redox balancing. Here, we find that Phenazines promote tolerance to clinically relevant antibiotics, such as ciprofloxacin, in P. aeruginosa biofilms and that this effect depends on the carbon source provided for growth. We couple stable isotope labeling with stimulated Raman scattering microscopy to visualize biofilm metabolic activity in situ. This approach shows that Phenazines promote metabolism in microaerobic biofilm regions and influence metabolic responses to ciprofloxacin treatment. Consistent with roles of specific respiratory complexes in supporting Phenazine utilization in biofilms, Phenazine-dependent survival on ciprofloxacin is diminished in mutants lacking these enzymes. Our work introduces a technique for the chemical imaging of biosynthetic activity in biofilms and highlights complex interactions between bacterial products, their effects on biofilm metabolism, and the antibiotics we use to treat infections.
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the pseudomonas aeruginosa efflux pump mexghi opmd transports a natural Phenazine that controls gene expression and biofilm development
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Hassan Sakhtah, Alexa Pricewhelan, Deborah A Hogan, Diana K Morales, Leslie Koyama, Yihan Zhang, Blanche L Fields, Kenneth L Shepard, Lars E P DietrichAbstract:Redox-cycling compounds, including endogenously produced Phenazine antibiotics, induce expression of the efflux pump MexGHI-OpmD in the opportunistic pathogen Pseudomonas aeruginosa. Previous studies of P. aeruginosa virulence, physiology, and biofilm development have focused on the blue Phenazine pyocyanin and the yellow Phenazine-1-carboxylic acid (PCA). In P. aeruginosa Phenazine biosynthesis, conversion of PCA to pyocyanin is presumed to proceed through the intermediate 5-methylPhenazine-1-carboxylate (5-Me-PCA), a reactive compound that has eluded detection in most laboratory samples. Here, we apply electrochemical methods to directly detect 5-Me-PCA and find that it is transported by MexGHI-OpmD in P. aeruginosa strain PA14 planktonic and biofilm cells. We also show that 5-Me-PCA is sufficient to fully induce MexGHI-OpmD expression and that it is required for wild-type colony biofilm morphogenesis. These physiological effects are consistent with the high redox potential of 5-Me-PCA, which distinguishes it from other well-studied P. aeruginosa Phenazines. Our observations highlight the importance of this compound, which was previously overlooked due to the challenges associated with its detection, in the context of P. aeruginosa gene expression and multicellular behavior. This study constitutes a unique demonstration of efflux-based self-resistance, controlled by a simple circuit, in a Gram-negative pathogen.
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integrated circuit based electrochemical sensor for spatially resolved detection of redox active metabolites in biofilms
Nature Communications, 2014Co-Authors: Daniel L Bellin, Lars E P Dietrich, Hassan Sakhtah, Jacob K Rosenstein, Peter M Levine, Jordan Thimot, Kevin J Emmett, Kenneth L ShepardAbstract:Despite advances in monitoring spatiotemporal expression patterns of genes and proteins with fluorescent probes, direct detection of metabolites and small molecules remains challenging. A technique for spatially resolved detection of small molecules would benefit the study of redox-active metabolites that are produced by microbial biofilms and can affect their development. Here we present an integrated circuit-based electrochemical sensing platform featuring an array of working electrodes and parallel potentiostat channels. ‘Images’ over a 3.25 � 0.9 mm 2 area can be captured with a diffusion-limited spatial resolution of 750mm. We demonstrate that square wave voltammetry can be used to detect, identify and quantify (for concentrations as low as 2.6mM) four distinct redox-active metabolites called Phenazines. We characterize Phenazine production in both wild-type and mutant Pseudomonas aeruginosa PA14 colony biofilms, and find correlations with fluorescent reporter imaging of Phenazine biosynthetic gene expression.
Linda S Thomashow - One of the best experts on this subject based on the ideXlab platform.
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global landscape of Phenazine biosynthesis and biodegradation reveals species specific colonization patterns in agricultural soils and crop microbiomes
eLife, 2020Co-Authors: Daniel Dar, Linda S Thomashow, David M Weller, Dianne K NewmanAbstract:Phenazines are natural bacterial antibiotics that can protect crops from disease. However, for most crops it is unknown which producers and specific Phenazines are ecologically relevant, and whether Phenazine biodegradation can counter their effects. To better understand their ecology, we developed and environmentally-validated a quantitative metagenomic approach to mine for Phenazine biosynthesis and biodegradation genes, applying it to >800 soil and plant-associated shotgun-metagenomes. We discover novel producer-crop associations and demonstrate that Phenazine biosynthesis is prevalent across habitats and preferentially enriched in rhizospheres, whereas biodegrading bacteria are rare. We validate an association between maize and Dyella japonica, a putative producer abundant in crop microbiomes. D. japonica upregulates Phenazine biosynthesis during phosphate limitation and robustly colonizes maize seedling roots. This work provides a global picture of Phenazines in natural environments and highlights plant-microbe associations of agricultural potential. Our metagenomic approach may be extended to other metabolites and functional traits in diverse ecosystems.
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biological control of rhizoctonia root rot on bean by Phenazine and cyclic lipopeptide producing pseudomonas cmr12a
Phytopathology, 2011Co-Authors: Jolien Daes, Lars E P Dietrich, Marc Ongena, Gia Khuong Hoang Hua, Dmitri V Mavrodi, Linda S Thomashow, Katrien De Maeyer, Joke Pannecoucque, Ilse Forrez, Monica HöfteAbstract:Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing Phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of Phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia solani, the intermediately aggressive AG 2-2 and the highly aggressive AG 4 HGI, were included in growth-chamber experiments with bean plants. The wild-type strain CMR12a dramatically reduced disease severity caused by both R. solani AGs. A CLP-deficient and a Phenazine-deficient mutant of CMR12a still protected bean plants, albeit to a lesser extent compared with the wild type. Two mutants deficient in both Phenazine and CLP production completely lost their biocontrol activity. Disease-suppressive capacity of CMR12a decreased after washing bacteria before application to soil and thereby removing metabolites produced during growth on plate. In addition, microscopic observations revealed pronounced branching of hyphal tips of both R. solani AGs in the presence of CMR12a. More branched and denser mycelium was also observed for the Phenazine-deficient mutant; however, neither the CLP-deficient mutant nor the mutants deficient in both CLPs and Phenazines influenced hyphal growth. Together, results demonstrate the involvement of Phenazines and CLPs during Pseudomonas CMR12a-mediated biocontrol of Rhizoctonia root rot of bean.
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biological control of rhizoctonia root rot on bean by Phenazine and cyclic lipopeptide producing pseudomonas cmr12a
Phytopathology, 2011Co-Authors: Jolien Daes, Lars E P Dietrich, Marc Ongena, Dmitri V Mavrodi, Linda S Thomashow, Katrien De Maeyer, Joke Pannecoucque, Ilse Forrez, Monica HöfteAbstract:D’aes, J., Hua, G. K. H., De Maeyer, K., Pannecoucque, J., Forrez, I., Ongena, M., Dietrich, L. E. P., Thomashow, L. S., Mavrodi, D. V., and Hofte, M. 2011. Biological control of Rhizoctonia root rot on bean by Phenazine- and cyclic lipopeptide-producing Pseudomonas CMR12a. Phytopathology 101:996-1004. Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing Phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of Phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia solani, the intermediately aggressive AG 2-2 and the highly aggressive AG 4 HGI, were included in growth-chamber experiments with bean plants. The wild-type strain CMR12a dramatically reduced disease severity caused by both R. solani AGs. A CLP-deficient and a Phenazine-deficient mutant of CMR12a still protected bean plants, albeit to a lesser extent compared with the wild type. Two mutants deficient in both Phenazine and CLP production completely lost their biocontrol activity. Disease-suppressive capacity of CMR12a decreased after washing bacteria before application to soil and thereby removing metabolites produced during growth on plate. In addition, microscopic observations revealed pronounced branching of hyphal tips of both R. solani AGs in the presence of CMR12a. More branched and denser mycelium was also observed for the Phenazine-deficient mutant; however, neither the CLP-deficient mutant nor the mutants deficient in both CLPs and Phenazines influenced hyphal growth. Together, results demonstrate the involvement of Phenazines and CLPs during Pseudomonas CMR12amediated biocontrol of Rhizoctonia root rot of bean.
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Phenazine compounds in fluorescent pseudomonas spp biosynthesis and regulation
Annual Review of Phytopathology, 2006Co-Authors: Dmitri V Mavrodi, Wulf Blankenfeldt, Linda S ThomashowAbstract:Abstract The Phenazines include upward of 50 pigmented, heterocyclic nitrogen-containing secondary metabolites synthesized by some strains of fluorescent Pseudomonas spp. and a few other bacterial genera. The antibiotic properties of these compounds have been known for over 150 years, but advances within the past two decades have provided significant new insights into the genetics, biochemistry, and regulation of Phenazine synthesis, as well as the mode of action and functional roles of these compounds in the environment. This new knowledge reveals conservation of biosynthetic enzymes across genera but raises questions about conserved biosynthetic mechanisms, and sets the stage for improving the performance of Phenazine producers used as biological control agents for soilborne plant pathogens.
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functional analysis of genes for biosynthesis of pyocyanin and Phenazine 1 carboxamide from pseudomonas aeruginosa pao1
Journal of Bacteriology, 2001Co-Authors: Dmitri V Mavrodi, Robert F Bonsall, Shannon M Delaney, Marilyn Soule, Greg Phillips, Linda S ThomashowAbstract:Phenazine compounds produced by fluorescent Pseudomonas species are biologically active metabolites that function in microbial competitiveness (37), the suppression of soilborne plant pathogens (1, 11, 55, 56), and virulence in human and animal hosts (35). The most widely studied Phenazine-producing fluorescent pseudomonad is P. aeruginosa, a gram-negative opportunistic pathogen of animals, insects, nematodes, and plants (30, 33, 35, 46). In humans, P. aeruginosa infects immunocompromised, burned, or injured patients and can cause both acute and chronic lung disease. Strains of P. aeruginosa produce a variety of redox-active Phenazine compounds, including pyocyanin, Phenazine-1-carboxylic acid (PCA), 1-hydroxyPhenazine (1-OH-PHZ), and Phenazine-1-carboxamide (PCN) (7, 52, 57). From 90 to 95% of P. aeruginosa isolates produce pyocyanin (52), and the presence of high concentrations of pyocyanin in the sputum of cystic fibrosis patients has suggested that this compound plays a role in pulmonary tissue damage observed with chronic lung infections (64). This idea is supported by several recent studies which demonstrated that pyocyanin contributes in a variety of ways to the pathophysiological effects observed in airways infected by P. aeruginosa. Pyocyanin interferes with the regulation of ion transport, ciliary beat frequency, and mucus secretion in airway epithelial cells by altering the cytosolic concentration of calcium (15). It may interact with endothelium-derived relaxing factor or with nitric oxide (which plays a central role in the control of blood pressure, blood flow, and immune function) through the formation of a complex, or it may act by inhibition of nitric oxide synthase (29, 58, 59). Phenazines that are produced by P. aeruginosa also can stimulate alveolar macrophages to produce two neutrophil chemotaxins, IL-8 and leukotriene B4, that attract neutrophils into airways, causing an inflammatory response and neutrophil-mediated tissue damage (14, 33). The unusually broad range of biological activity associated with Phenazines is thought to be due to their ability to undergo redox cycling in the presence of various reducing agents and molecular oxygen, which leads to the accumulation of toxic superoxide (O2−) and hydrogen peroxide (H2O2) and eventually to oxidative cell injury or death (6, 25). It also has been shown that pyocyanin can interact synergistically with the siderophore pyochelin and with transferrin cleaved by proteases secreted by both P. aeruginosa and neutrophils in infected lungs to catalyze the formation of the highly cytotoxic hydroxyl radical (·OH), which damages pulmonary endothelial cells (6, 38). In model pathogenesis systems, Phenazine synthesis by P. aeruginosa is required for the generation of disease symptoms in plants and for effective killing of the nematode Caenorhabditis elegans and the greater wax moth, Galleria mellonella (30, 35, 46). Phenazine compounds produced in the rhizosphere of plants contribute to the biological control activity of P. aeruginosa against Fusarium wilt of chickpea and Pythium damping-off of bean (1). Although the pathophysiological effects of Phenazines produced by P. aeruginosa in host organisms are well studied (6, 14, 15, 33, 34, 38, 64) and pyocyanin-deficient phenotypes frequently have been described (18, 19, 26, 32, 35, 46, 54), the biochemistry and genetics of Phenazine synthesis in P. aeruginosa have remained unclear. We describe here cloning and functional analysis of two seven-gene Phenazine operons and three Phenazine-modifying genes from P. aeruginosa PAO1. Our results show that P. aeruginosa contains a complex Phenazine biosynthetic pathway consisting of two homologous core loci (phzA1B1C1D1E1F1G1 and phzA2B2C2D2E2F2G2) responsible for synthesis of PCA and three additional genes (phzM, phzS, and phzH) encoding unique enzymes involved in the conversion of PCA to pyocyanin and PCN. We detected the core biosynthetic operon by Southern hybridization in 21 Phenazine-producing pseudomonads, including strains of P. aeruginosa, Pseudomonas fluorescens, Pseudomonas chlororaphis, and Pseudomonas aureofaciens, but not in seven Phenazine-producing isolates of Burkholderia cepacia, Burkholderia phenazinium, and Brevibacterium iodinum. Thus, the core biosynthetic pathway is highly conserved in fluorescent Pseudomonas spp. but differs significantly from that in other Phenazine-producing bacterial genera.
Monica Höfte - One of the best experts on this subject based on the ideXlab platform.
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Role of Phenazines and cyclic lipopeptides produced by pseudomonas sp. CMR12a in induced systemic resistance on rice and bean
Environmental microbiology reports, 2016Co-Authors: Gia Khuong Hoang Hua, Marc Ongena, Monica HöfteAbstract:Pseudomonas sp. CMR12a produces two different classes of cyclic lipopeptides (CLPs) (orfamides and sessilins), which all play a role in direct antagonism against soilborne pathogens. Here we show that Pseudomonas sp. CMR12a is also able to induce systemic resistance to Magnaporthe oryzae on rice and to the web blight pathogen Rhizoctonia solani AG2-2 on bean. Plant assays with biosynthesis mutants of Pseudomonas sp. CMR12a impaired in the production of Phenazines and/or CLPs and purified metabolites revealed that distinct bacterial determinants are responsible for inducing systemic resistance in these two pathosystems. In rice, mutants impaired in Phenazine production completely lost their ability to induce systemic resistance, while a soil drench with pure Phenazine-1-carboxamide (PCN) at a concentration of 0.1 or 1 μM was active in inducing resistance against M. oryzae. In bean, mutants that only produced Phenazines, sessilins or orfamides were still able to induce systemic resistance against Rhizoctonia web blight, but a balanced production of these metabolites was needed. This study not only shows that Pseudomonas sp. CMR12a can protect rice to blast disease and bean to web blight disease, but also displays that the determinants involved in induced systemic resistance are plant, pathogen and concentration dependent.
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biological control of rhizoctonia root rot on bean by Phenazine and cyclic lipopeptide producing pseudomonas cmr12a
Phytopathology, 2011Co-Authors: Jolien Daes, Lars E P Dietrich, Marc Ongena, Gia Khuong Hoang Hua, Dmitri V Mavrodi, Linda S Thomashow, Katrien De Maeyer, Joke Pannecoucque, Ilse Forrez, Monica HöfteAbstract:Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing Phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of Phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia solani, the intermediately aggressive AG 2-2 and the highly aggressive AG 4 HGI, were included in growth-chamber experiments with bean plants. The wild-type strain CMR12a dramatically reduced disease severity caused by both R. solani AGs. A CLP-deficient and a Phenazine-deficient mutant of CMR12a still protected bean plants, albeit to a lesser extent compared with the wild type. Two mutants deficient in both Phenazine and CLP production completely lost their biocontrol activity. Disease-suppressive capacity of CMR12a decreased after washing bacteria before application to soil and thereby removing metabolites produced during growth on plate. In addition, microscopic observations revealed pronounced branching of hyphal tips of both R. solani AGs in the presence of CMR12a. More branched and denser mycelium was also observed for the Phenazine-deficient mutant; however, neither the CLP-deficient mutant nor the mutants deficient in both CLPs and Phenazines influenced hyphal growth. Together, results demonstrate the involvement of Phenazines and CLPs during Pseudomonas CMR12a-mediated biocontrol of Rhizoctonia root rot of bean.
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biological control of rhizoctonia root rot on bean by Phenazine and cyclic lipopeptide producing pseudomonas cmr12a
Phytopathology, 2011Co-Authors: Jolien Daes, Lars E P Dietrich, Marc Ongena, Dmitri V Mavrodi, Linda S Thomashow, Katrien De Maeyer, Joke Pannecoucque, Ilse Forrez, Monica HöfteAbstract:D’aes, J., Hua, G. K. H., De Maeyer, K., Pannecoucque, J., Forrez, I., Ongena, M., Dietrich, L. E. P., Thomashow, L. S., Mavrodi, D. V., and Hofte, M. 2011. Biological control of Rhizoctonia root rot on bean by Phenazine- and cyclic lipopeptide-producing Pseudomonas CMR12a. Phytopathology 101:996-1004. Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing Phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of Phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia solani, the intermediately aggressive AG 2-2 and the highly aggressive AG 4 HGI, were included in growth-chamber experiments with bean plants. The wild-type strain CMR12a dramatically reduced disease severity caused by both R. solani AGs. A CLP-deficient and a Phenazine-deficient mutant of CMR12a still protected bean plants, albeit to a lesser extent compared with the wild type. Two mutants deficient in both Phenazine and CLP production completely lost their biocontrol activity. Disease-suppressive capacity of CMR12a decreased after washing bacteria before application to soil and thereby removing metabolites produced during growth on plate. In addition, microscopic observations revealed pronounced branching of hyphal tips of both R. solani AGs in the presence of CMR12a. More branched and denser mycelium was also observed for the Phenazine-deficient mutant; however, neither the CLP-deficient mutant nor the mutants deficient in both CLPs and Phenazines influenced hyphal growth. Together, results demonstrate the involvement of Phenazines and CLPs during Pseudomonas CMR12amediated biocontrol of Rhizoctonia root rot of bean.