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Microbial Biotechnology Nov 2023Virulence factor modulating (VFM) is a quorum sensing (QS) signal shared by and specific to Dickeya bacteria, regulating the production of plant cell wall degrading...
Virulence factor modulating (VFM) is a quorum sensing (QS) signal shared by and specific to Dickeya bacteria, regulating the production of plant cell wall degrading enzymes (PCWDEs) and virulence of Dickeya. High polarity and trace of VFM signal increase the difficulty of signal separation and structure identification, and thus limit the development of quorum quenching strategy to biocontrol bacterial soft rot diseases caused by Dickeya. In order to high-throughput screen VFM quenching bacteria, a vfmE-gfp biosensor VR2 (VFM Reporter) sensitive to VFM signal was first constructed. Subsequently, two bacterial strains with high quenching efficiency were screened out by fluorescence intensity measurement and identified as Pseudomonas chlororaphis L5 and Enterobacter asburiae L95 using multilocus sequence analysis (MLSA). L5 and L95 supernatants reduced the expression of vfm genes, and both strains also decreased the production of PCWDEs of D. zeae MS2 and significantly reduced the virulence of D. oryzae EC1 on rice seedlings, D. zeae MS2 on banana seedlings, D. dadantii 3937 on potato and D. fangzhongdai CL3 on taro. Findings in this study provide a method to high-throughput screen VFM quenching bacteria and characterize novel functions of P. chlororaphis and E. asburiae in biocontrolling plant diseases through quenching VFM QS signal.
Topics: Virulence Factors; Dickeya; Quorum Sensing; Pseudomonas chlororaphis; Enterobacteriaceae; Plant Diseases
PubMed: 37815509
DOI: 10.1111/1751-7915.14351 -
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 -
Pathogens (Basel, Switzerland) Jul 2021Wheat is a worldwide staple food crop, and take-all caused by var. can lead to a tremendous decrease in wheat yield and quality. In this study, strain YB-10 was...
Wheat is a worldwide staple food crop, and take-all caused by var. can lead to a tremendous decrease in wheat yield and quality. In this study, strain YB-10 was isolated from wheat rhizospheric soil and identified as by morphology and 16S rRNA gene sequencing. YB-10 had extracellular protease and cellulase activities and strongly inhibited the mycelium growth of var. in dual cultures. Up to 87% efficacy of YB-10 in controlling the take-all of seedlings was observed in pot experiments when wheat seed was coated with the bacterium. YB-10 was also positive for indole acetic acid (IAA) and siderophore production, and coating wheat seed with the bacterium significantly promoted the growth of seedlings at 10 and 10 CFU/mL. Furthermore, treatment with YB-10 increased activities of the wheat defense-related enzymes POD, SOD, CAT, PAL and PPO in seedlings, indicating induced resistance against pathogens. Overall, YB-10 is a promising new seed-coating agent to both promote wheat growth and suppress take-all.
PubMed: 34358053
DOI: 10.3390/pathogens10070903 -
Frontiers in Microbiology 2023Phenazine-1-carboxylic acid (PCA) is a biologically active substance with the ability to prevent and control crop diseases. It was certified as a pesticide by the...
Phenazine-1-carboxylic acid (PCA) is a biologically active substance with the ability to prevent and control crop diseases. It was certified as a pesticide by the Ministry of Agriculture of China in 2011 and was named "Shenzimycin." Lzh-T5 is a strain found in the rhizosphere of tomatoes. This strain can produce only 230 mg/L of PCA. We used LDA-4, which produces the phenazine synthetic intermediate trans-2,3-dihydro-3-hydroxyanthranilic acid in high amounts, as the starting strain. By restoring and knocking out , we achieved PCA accumulation. Moreover, PCA production was enhanced after knocking out negative regulators, enhancing the shikimate pathway, and performing fed-batch fermentation, thus resulting in the production of 10,653 mg/L of PCA. It suggested that Lzh-T5 has the potential to become an efficiency cell factory of biologically active substances.
PubMed: 37168109
DOI: 10.3389/fmicb.2023.1186052 -
3 Biotech Jun 2023The recent advances in omics and computational analysis have enabled the capacity to identify the exclusive strain-specific metabolites and novel biosynthetic gene...
UNLABELLED
The recent advances in omics and computational analysis have enabled the capacity to identify the exclusive strain-specific metabolites and novel biosynthetic gene clusters. This study analyzed eight strains of including GS1, GS3, GS4, GS6, GS7, FS2, ARS38, PBSt2, one strain of RP4, one strain of (At1RP4), and one strain of (RS1) for the production of rhamnolipids, quorum-sensing signals, and osmolytes. Seven rhamnolipid derivatives were variably detected in fluorescent pseudomonads. These rhamnolipids included Rha-C-C, Rha-Rha-C-C, Rha-C-Cdb, Rha-C-C, Rha-Rha-C-C Rha-C-C, and Rha-Rha-C-Cdb. spp. also showed the variable production of osmoprotectants including N-acetyl glutaminyl glutamine amide (NAGGN), betaine, ectoine, and trehalose. Betaine and ectoine were produced by all pseudomonads, however, NAGGN and trehalose were observed by five and three strains, respectively. Four strains including (RP4), (At1RP4), (RS1), and (PBSt2) were exposed to 1- 4% NaCl concentrations and evaluated for the changes in phenazine production profile which were negligible. AntiSMASH 5.0 platform showed 50 biosynthetic gene clusters in PB-St2, of which 23 (45%) were classified as putative gene clusters with ClusterFinder algorithm, five (10%) were classified as non-ribosomal peptides synthetases (NRPS), five (10%) as saccharides, and four (8%) were classified as putative fatty acids. The genomic attributes and comprehensive insights into the metabolomic profile of these spp. strains showcase their phytostimulatory, phyto-protective, and osmoprotective effects of diverse crops grown in normal and saline soils.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1007/s13205-023-03607-x.
PubMed: 37193329
DOI: 10.1007/s13205-023-03607-x -
Journal of Agricultural and Food... Apr 2024Polyhydroxyalkanoates (PHAs) are promising alternatives to petroleum-based plastics, owing to their biodegradability and superior material properties. Here, the...
Polyhydroxyalkanoates (PHAs) are promising alternatives to petroleum-based plastics, owing to their biodegradability and superior material properties. Here, the controllable biosynthesis of scl--mcl PHA containing 3-hydroxybutyrate (3HB) and mcl 3-hydroxyalkanoates was achieved in HT66. First, key genes involved in fatty acid β-oxidation, the fatty acid biosynthesis pathway, and the -- operon were deleted to develop a chassis strain. Subsequently, an acetoacetyl-CoA reductase gene and a PHA synthase gene with broad substrate specificity were heterologously expressed for producing and polymerizing the 3HB monomer with mcl 3-hydroxyalkanoates under the assistance of native β-ketothiolase gene . Furthermore, the monomer composition of scl--mcl PHA was regulated by adjusting the amount of glucose and dodecanoic acid supplemented. Notably, the cell dry weight and scl--mcl PHA content reached 14.2 g/L and 60.1 wt %, respectively, when the engineered strain HT11Δ:: was cultured in King's B medium containing 5 g/L glucose and 5 g/L dodecanoic acid. These results demonstrated that can be a platform for producing scl--mcl PHA and has the potential for industrial application.
Topics: 3-Hydroxybutyric Acid; Pseudomonas chlororaphis; Acyltransferases; Polyhydroxyalkanoates; Glucose
PubMed: 38564621
DOI: 10.1021/acs.jafc.4c00777 -
Microbial Biotechnology Jan 2021Rhamnolipids are biosurfactants with a wide range of industrial applications that entered into the market a decade ago. They are naturally produced by Pseudomonas... (Review)
Review
Rhamnolipids are biosurfactants with a wide range of industrial applications that entered into the market a decade ago. They are naturally produced by Pseudomonas aeruginosa and some Burkholderia species. Occasionally, some strains of different bacterial species, like Pseudomonas chlororaphis NRRL B-30761, which have acquired RL-producing ability by horizontal gene transfer, have been described. P. aeruginosa, the ubiquitous opportunistic pathogenic bacterium, is the best rhamnolipids producer, but Pseudomonas putida has been used as heterologous host for the production of this biosurfactant with relatively good yields. The molecular genetics of rhamnolipids production by P. aeruginosa has been widely studied not only due to the interest in developing overproducing strains, but because it is coordinately regulated with the expression of different virulence-related traits by the quorum-sensing response. Here, we highlight how the research of the molecular mechanisms involved in rhamnolipid production have impacted the development of strains that are suitable for industrial production of this biosurfactant, as well as some perspectives to improve these industrial useful strains.
Topics: Glycolipids; Molecular Biology; Pseudomonas; Pseudomonas aeruginosa; Pseudomonas putida; Surface-Active Agents
PubMed: 33151628
DOI: 10.1111/1751-7915.13700 -
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 -
Frontiers in Microbiology 2024The rhizosphere microbiome is critical to plant health and resistance. PGPR are well known as plant-beneficial bacteria and generally regulate nutrient utilization as...
INTRODUCTION
The rhizosphere microbiome is critical to plant health and resistance. PGPR are well known as plant-beneficial bacteria and generally regulate nutrient utilization as well as plant responses to environmental stimuli. In our previous work, one typical PGPR strain, IRHB3, isolated from the soybean rhizosphere, had positive impacts on soil-borne disease suppression and growth promotion in the greenhouse, but its biocontrol mechanism and application in the field are not unclear.
METHODS
In the current study, IRHB3 was introduced into field soil, and its effects on the local rhizosphere microbiome, disease resistance, and soybean growth were comprehensively analyzed through high-throughput sequencing and physiological and molecular methods.
RESULTS AND DISCUSSION
We found that IRHB3 significantly increased the richness of the bacterial community but not the structure of the soybean rhizosphere. Functional bacteria related to phosphorus solubilization and nitrogen fixation, such as , , , , and , were recruited in rich abundance by IRHB3 to the soybean rhizosphere as compared to those without IRHB3. In addition, the IRHB3 supplement obviously maintained the homeostasis of the rhizosphere microbiome that was disturbed by , resulting in a lower disease index of root rot when compared with . Furthermore, JA-mediated induced resistance was rapidly activated by IRHB3 following and expression, and meanwhile, a set of nodulation genes, , , and , were also considerably induced by IRHB3 to improve nitrogen fixation ability and promote soybean yield, even when plants were infected by . Thus, IRHB3 tends to synergistically interact with local rhizosphere microbes to promote host growth and induce host resistance in the field.
PubMed: 38380096
DOI: 10.3389/fmicb.2024.1328863 -
Microbial Biotechnology Jan 2024Rhamnolipids (RL) are biosurfactants naturally produced by the opportunistic pathogen Pseudomonas aeruginosa. Currently, RL are commercialized for various applications...
Rhamnolipids (RL) are biosurfactants naturally produced by the opportunistic pathogen Pseudomonas aeruginosa. Currently, RL are commercialized for various applications and produced by Pseudomonas putida due to the health risks associated with their large-scale production by P. aeruginosa. In this work, we show that RL containing one or two rhamnose moieties (mono-RL or di-RL, respectively) can be produced by the innocuous soil-bacterium Pseudomonas chlororaphis subsp chlororaphis ATCC 9446 at titres up to 66 mg/L (about 86% of the production of P. aeruginosa PAO1 in the same culture conditions). The production of RL depends on the expression of P. aeruginosa PAO1 genes encoding the enzymes RhlA, RhlB and RhlC. These genes were introduced in a plasmid, together with a transcriptional regulator (rhlR) forming part of the same operon, with and without RhlC. We show that the activation of rhlAB by RhlR depends on its interaction with P. chlororaphis endogenous acyl-homoserine lactones, which are synthetized by either PhzI or CsaI autoinducer synthases (producing 3-hydroxy-hexanoyl homoserine lactone, 3OH-C6-HSL, or 3-oxo-hexanoyl homoserine lactone, 3O-C6-HSL, respectively). P. chlororaphis transcriptional regulator couple with 3OH-C6-HSL is the primary activator of gene expression for phenazine-1-carboxylic acid (PCA) and phenazine-1-carboxamide (PCN) production in this soil bacterium. We show that RhlR coupled with 3OH-C6-HSL or 3O-C6-HSL promotes RL production and increases the production of PCA in P. chlororaphis. However, PhzR/3OH-C6-HSL or CsaR/3O-C6-HSL cannot activate the expression of the rhlAB operon to produce mono-RL. These results reveal a complex regulatory interaction between RhlR and P. chlororaphis quorum-sensing signals and highlight the biotechnology potential of P. chlororaphis ATCC 9446 expressing P. aeruginosa rhlAB-R or rhlAB-R-C for the industrial production of RL.
Topics: Pseudomonas chlororaphis; Acyl-Butyrolactones; Pseudomonas aeruginosa; Soil; Bacterial Proteins; Glycolipids; Pseudomonas; 4-Butyrolactone
PubMed: 38041625
DOI: 10.1111/1751-7915.14377