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World Journal of Microbiology &... May 2021The Pseudomonas fluorescens complex contains at least eight phylogenetic groups and each of these includes several bacterial species sharing ecological and physiological... (Review)
Review
The Pseudomonas fluorescens complex contains at least eight phylogenetic groups and each of these includes several bacterial species sharing ecological and physiological traits. Pseudomonas chlororaphis classified in a separate group is represented by three different subspecies that show distinctive traits exploitable for phytostimulation and biocontrol of phytopathogens. The high level of microbial competitiveness in soil as well as the effectiveness in controlling several plant pathogens and pests can be related to the P. chlororaphis ability to implement different stimulating and toxic mechanisms in its interaction with plants and the other micro- and macroorganisms. Pseudomonas chlororaphis strains produce antibiotics, such as phenazines, pyrrolnitrine, 2-hexyl, 5-propyl resorcinol and hydrogen cyanide, siderophores such as pyoverdine and achromobactine and a complex blend of volatile organic compounds (VOCs) that effectively contribute to the control of several plant pathogens, nematodes and insects. Phenazines and some VOCs are also involved in the induction of systemic resistance in plants. This complex set of beneficial strategies explains the high increasing interest in P. chlororaphis for commercial and biotechnological applications. The aim of this review is to highlight the role of the different mechanisms involved in the biocontrol activity of P. chlororaphis strains.
Topics: Biological Control Agents; Disease Resistance; Phylogeny; Plant Development; Pseudomonas chlororaphis; Secondary Metabolism
PubMed: 33978868
DOI: 10.1007/s11274-021-03063-w -
Journal of Medical Microbiology Mar 2020isolates have been studied intensively for their beneficial traits. species function as probiotics in plants and fish, offering plants protection against microbes,... (Review)
Review
isolates have been studied intensively for their beneficial traits. species function as probiotics in plants and fish, offering plants protection against microbes, nematodes and insects. In this review, we discuss the classification of isolates within four subspecies; the shared traits include the production of coloured antimicrobial phenazines, high sequence identity between housekeeping genes and similar cellular fatty acid composition. The direct antimicrobial, insecticidal and nematocidal effects of isolates are correlated with known metabolites. Other metabolites prime the plants for stress tolerance and participate in microbial cell signalling events and biofilm formation among other things. Formulations of isolates and their metabolites are currently being commercialized for agricultural use.
Topics: Acyl-Butyrolactones; Agriculture; Anti-Infective Agents; Antinematodal Agents; Biofilms; Hydrogen Cyanide; Insecticides; Phenazines; Phenotype; Plants; Probiotics; Pseudomonas chlororaphis; Pyrrolnitrin; Resorcinols; Siderophores; Volatile Organic Compounds
PubMed: 32043956
DOI: 10.1099/jmm.0.001157 -
Transgenic Research Feb 2018Genetically modified crops undergo extensive evaluation to characterize their food, feed and environmental safety prior to commercial introduction, using a... (Review)
Review
Genetically modified crops undergo extensive evaluation to characterize their food, feed and environmental safety prior to commercial introduction, using a well-established, science-based assessment framework. One component of the safety assessment includes an evaluation of each introduced trait, including its source organism, for potential adverse pathogenic, toxic and allergenic effects. Several Pseudomonas species have a history of safe use in agriculture and certain species represent a source of genes with insecticidal properties. The ipd072Aa gene from P. chlororaphis encodes the IPD072Aa protein, which confers protection against certain coleopteran pests when expressed in maize plants. P. chlororaphis is ubiquitous in the environment, lacks known toxic or allergenic properties, and has a history of safe use in agriculture and in food and feed crops. This information supports, in part, the safety assessment of potential traits, such as IPD072Aa, that are derived from this source organism.
Topics: Bacterial Proteins; Biological Control Agents; Crops, Agricultural; Insecticides; Phylogeny; Plants, Genetically Modified; Pseudomonas chlororaphis; Zea mays
PubMed: 29427161
DOI: 10.1007/s11248-018-0061-6 -
EFSA Journal. European Food Safety... Jan 2017The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, the... (Review)
Review
The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, the Netherlands, and co-rapporteur Member State, Denmark, for the pesticide active substance strain MA 342 are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of strain MA 342 as a seed treatment in cereals (wheat, rye and triticale), carrots and peas against seed-borne diseases and foliar application in cereals against foliar and ear pathogens. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.
PubMed: 32625261
DOI: 10.2903/j.efsa.2017.4668 -
Frontiers in Microbiology 2019The goal of this mini review is to summarize the relevant contribution of some beneficial traits to the behavior of the species , and using that information, to give a... (Review)
Review
The goal of this mini review is to summarize the relevant contribution of some beneficial traits to the behavior of the species , and using that information, to give a practical point of view using the model biocontrol strain PCL1606 (PcPCL1606). Among the group of plant-beneficial rhizobacteria, has emerged as a plant- and soil-related bacterium that is mainly known because of its biological control of phytopathogenic fungi. Many traits have been reported to be crucial during the multitrophic interaction involving the plant, the fungal pathogen and the soil environment. To explore the different biocontrol-related traits, the biocontrol rhizobacterium PcPCL1606 has been used as a model in recent studies. This bacterium is antagonistic to many phytopathogenic fungi and displays effective biocontrol against fungal phytopathogens. Antagonistic and biocontrol activities are directly related to the production of the compound 2-hexyl, 5-propyl resorcinol (HPR), despite the production of other antifungal compounds. Furthermore, PcPCL1606 has displayed additional traits regarding its fitness in soil and plant root environments such as soil survival, efficient plant root colonization, cell-to-cell interaction or promotion of plant growth.
PubMed: 31024497
DOI: 10.3389/fmicb.2019.00719 -
Scientific Reports Aug 2021Trans-2,3-dihydro-3-hydroxyanthranilic acid (DHHA) is a cyclic β-amino acid used for the synthesis of non-natural peptides and chiral materials. And it is an...
Trans-2,3-dihydro-3-hydroxyanthranilic acid (DHHA) is a cyclic β-amino acid used for the synthesis of non-natural peptides and chiral materials. And it is an intermediate product of phenazine production in Pseudomonas spp. Lzh-T5 is a P. chlororaphis strain isolated from tomato rhizosphere found in China. It can synthesize three antifungal phenazine compounds. Disruption the phzF gene of P. chlororaphis Lzh-T5 results in DHHA accumulation. Several strategies were used to improve production of DHHA: enhancing the shikimate pathway by overexpression, knocking out negative regulatory genes, and adding metal ions to the medium. In this study, three regulatory genes (psrA, pykF, and rpeA) were disrupted in the genome of P. chlororaphis Lzh-T5, yielding 5.52 g/L of DHHA. When six key genes selected from the shikimate, pentose phosphate, and gluconeogenesis pathways were overexpressed, the yield of DHHA increased to 7.89 g/L. Lastly, a different concentration of Fe was added to the medium for DHHA fermentation. This genetically engineered strain increased the DHHA production to 10.45 g/L. According to our result, P. chlororaphis Lzh-T5 could be modified as a microbial factory to produce DHHA. This study laid a good foundation for the future industrial production and application of DHHA.
Topics: 3-Hydroxyanthranilic Acid; Culture Media; Fermentation; Ferric Compounds; Gene Knockdown Techniques; Genes, Bacterial; Genes, Regulator; Phenazines; Pseudomonas chlororaphis
PubMed: 34385485
DOI: 10.1038/s41598-021-94674-8 -
New Biotechnology Mar 2020Pseudomonas chlororaphis subsp. aurantiaca DSM 19603 was cultivated using glycerol as the sole carbon source for the simultaneous production of medium-chain length...
Pseudomonas chlororaphis subsp. aurantiaca DSM 19603 was cultivated using glycerol as the sole carbon source for the simultaneous production of medium-chain length polyhydroxyalkanoates (mcl-PHA), extracellular polysaccharide (EPS) and phenazines. A maximum cell dry mass of 11.79 g/L was achieved with a mcl-PHA content of 19 wt%, corresponding to a polymer concentration of 2.23 g/L. A considerably higher EPS production, 6.10 g/L, was attained. Phenazines synthesis was evidenced by the bright orange coloration developed by the culture during the cell growth phase. The mcl-PHA produced by P. chlororaphis was composed mainly of 3-hydroxydecanoate (50 wt%) with lower amounts of 3-hydroxyoctanoate (17 wt%), 3-hydroxytetradecanoate (17 wt%), 3-hydroxydodecanoate (13 wt%) and 3-hydroxyhexanoate (3 wt%). This PHA showed unique thermal features being highly amorphous, with a degree of crystallinity of 27% and a low melting temperature (45.0 °C). The secreted EPS was mostly composed of glucose, glucosamine, rhamnose and mannose, with smaller amounts of three other unidentified monomers. Although the bioprocess can be improved further to define the optimal conditions to produce each bioproduct (mcl-PHA, EPS or phenazines), this study has demonstrated for the first time the ability of P. chlororaphis to simultaneously produce three high-value products from a single substrate.
Topics: Biomass; Biopolymers; Glycerol; Kinetics; Phenazines; Polyhydroxyalkanoates; Polysaccharides, Bacterial; Pseudomonas chlororaphis; X-Ray Diffraction
PubMed: 31605767
DOI: 10.1016/j.nbt.2019.10.002 -
PeerJ 2021strain PA23 is a biocontrol agent that is able to protect canola against the pathogenic fungus . This bacterium secretes a number of metabolites that contribute to...
BACKGROUND
strain PA23 is a biocontrol agent that is able to protect canola against the pathogenic fungus . This bacterium secretes a number of metabolites that contribute to fungal antagonism, including pyrrolnitrin (PRN), phenazine (PHZ), hydrogen cyanide (HCN) and degradative enzymes. In order to be successful, a biocontrol agent must be able to persist in the environment and avoid the threat of grazing predators. The focus of the current study was to investigate whether PA23 is able to resist grazing by the protozoan predator (Ac) and to define the role of bacterial metabolites in the PA23-Ac interaction.
METHODS
Ac was co-cultured with PA23 WT and a panel of derivative strains for a period of 15 days, and bacteria and amoebae were enumerated on days 1, 5, 10 and 15. Ac was subsequently incubated in the presence of purified PRN, PHZ, and KCN and viability was assessed at 24, 48 and 72 h. Chemotactic assays were conducted to assess whether PA23 compounds exhibit repellent or attractant properties towards Ac. Finally, PA23 grown in the presence and absence of amoebae was subject to phenotypic characterization and gene expression analyses.
RESULTS
PRN, PHZ and HCN were found to contribute to PA23 toxicity towards Ac trophozoites, either by killing or inducing cyst formation. This is the first report of PHZ-mediated toxicity towards amoebae. In chemotaxis assays, amoebae preferentially migrated towards regulatory mutants devoid of extracellular metabolite production as well as a PRN mutant, indicating this antibiotic has repellent properties. Co-culturing of bacteria with amoebae led to elevated expression of the PA23 / quorum-sensing (QS) genes and and , which are under QS control. PHZ and PRN levels were similarly increased in Ac co-cultures, suggesting that PA23 can respond to predator cues and upregulate expression of toxins accordingly.
CONCLUSIONS
PA23 compounds including PRN, PHZ and HCN exhibited both toxic and repellent effects on Ac. Co-culturing of bacteria and amoebae lead to changes in bacterial gene expression and secondary metabolite production, suggesting that PA23 can sense the presence of these would-be predators and adjust its physiology in response.
PubMed: 33552738
DOI: 10.7717/peerj.10756 -
International Microbiology : the... Nov 2022The biocontrol rhizobacterium Pseudomonas chlororaphis is one of the bacterial species of the P. fluorescens group where insecticide fit genes have been found. Fit...
The biocontrol rhizobacterium Pseudomonas chlororaphis is one of the bacterial species of the P. fluorescens group where insecticide fit genes have been found. Fit toxin, supported with other antimicrobial compounds, gives the bacterial the ability to repel and to fight against eukaryotic organisms, such as nematodes and insect larvae, thus protecting the plant host and itself. Pseudomonas chlororaphis PCL1606 is an antagonistic rhizobacterium isolated from avocado roots and show efficient biocontrol against fungal soil-borne disease. The main antimicrobial compound produced by P. chlororaphis PCL606 is 2-hexyl-5-propyl resorcinol (HPR), which plays a crucial role in effective biocontrol against fungal pathogens. Further analysis of the P. chlororaphis PCL1606 genome showed the presence of hydrogen cyanide (HCN), pyrrolnitrin (PRN), and homologous fit genes. To test the insecticidal activity and to determine the bases for such activity, single and double mutants on the biosynthetic genes of these four compounds were tested in a Galleria mellonella larval model using inoculation by injection. The results revealed that Fit toxin and HPR in combination are involved in the insecticide phenotype of P. chlororaphis PCL1606, and additional compounds such as HCN and PRN could be considered supporting compounds.
Topics: Anti-Infective Agents; Hydrogen Cyanide; Insecticides; Pseudomonas chlororaphis; Pyrrolnitrin; Resorcinols; Soil
PubMed: 35670867
DOI: 10.1007/s10123-022-00253-w -
Applied Microbiology and Biotechnology Dec 2020Pseudomonas chlororaphis is a plant-associated bacterium with reported antagonistic activity against different organisms and plant growth-promoting properties. P....
Pseudomonas chlororaphis is a plant-associated bacterium with reported antagonistic activity against different organisms and plant growth-promoting properties. P. chlororaphis possesses exciting biotechnological features shared with another Pseudomonas with a nonpathogenic phenotype. Part of the antagonistic role of P. chlororaphis is due to its production of a wide variety of phenazines. To expand the knowledge of the metabolic traits of this organism, we constructed the first experimentally validated genome-scale model of P. chlororaphis ATCC 9446, containing 1267 genes and 2289 reactions, and analyzed strategies to maximize its potential for the production of phenazine-1-carboxamide (PCN). The resulting model also describes the capability of P. chlororaphis to carry out the denitrification process and its ability to consume sucrose (Scr), trehalose, mannose, and galactose as carbon sources. Additionally, metabolic network analysis suggested fatty acids as the best carbon source for PCN production. Moreover, the optimization of PCN production was performed with glucose and glycerol. The optimal PCN production phenotype requires an increased carbon flux in TCA and glutamine synthesis. Our simulations highlight the intrinsic HO flux associated with PCN production, which may generate cellular stress in an overproducing strain. These results suggest that an improved antioxidative strategy could lead to optimal performance of phenazine-producing strains of P. chlororaphis. KEY POINTS : • This is the first publication of a metabolic model for a strain of P. chlororaphis. • Genome-scale model is worthy tool to increase the knowledge of a non model organism. • Fluxes simulations indicate a possible effect of HO on phenazines production. • P. chlororaphis can be a suitable model for a wide variety of compounds.
Topics: Hydrogen Peroxide; Phenazines; Pseudomonas; Pseudomonas chlororaphis
PubMed: 32984920
DOI: 10.1007/s00253-020-10913-4