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Microorganisms Mar 2022Rhizosphere colonization by phytobeneficial Pseudomonas spp. is pivotal in triggering their positive effects on plant health. Many Pseudomonas spp. Determinants,...
Rhizosphere colonization by phytobeneficial Pseudomonas spp. is pivotal in triggering their positive effects on plant health. Many Pseudomonas spp. Determinants, involved in rhizosphere colonization, have already been deciphered. However, few studies have explored the role played by specific plant genes in rhizosphere colonization by these bacteria. Using isogenic Arabidopsis thaliana mutants, we studied the effect of 20 distinct plant genes on rhizosphere colonization by two phenazine-producing P. chlororaphis strains of biocontrol interest, differing in their colonization abilities: DTR133, a strong rhizosphere colonizer and ToZa7, which displays lower rhizocompetence. The investigated plant mutations were related to root exudation, immunity, and root system architecture. Mutations in smb and shv3, both involved in root architecture, were shown to positively affect rhizosphere colonization by ToZa7, but not DTR133. While these strains were not promoting plant growth in wild-type plants, increased plant biomass was measured in inoculated plants lacking fez, wrky70, cbp60g, pft1 and rlp30, genes mostly involved in plant immunity. These results point to an interplay between plant genotype, plant growth and rhizosphere colonization by phytobeneficial Pseudomonas spp. Some of the studied genes could become targets for plant breeding programs to improve plant-beneficial Pseudomonas rhizocompetence and biocontrol efficiency in the field.
PubMed: 35336236
DOI: 10.3390/microorganisms10030660 -
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 -
Materials (Basel, Switzerland) Jul 2023Fibrous materials composed of core-sheath fibers from poly(ethylene oxide) (PEO), beeswax (BW) and 5-nitro-8-hydroxyquinoline (NQ) were prepared via the...
Fibrous materials composed of core-sheath fibers from poly(ethylene oxide) (PEO), beeswax (BW) and 5-nitro-8-hydroxyquinoline (NQ) were prepared via the self-organization of PEO and BW during the single-spinneret electrospinning of a homogeneous blend solution of the partners. Additionally, the application of the same approach enabled the preparation of fibrous materials composed of core-double sheath fibers from PEO, poly(L-lactide) (PLA) and NQ or 5-chloro-7-iodo-8-hydroxyquinoline (CQ), as well as from PEO, poly(ε-caprolactone) (PCL) and NQ. The consecutive selective extraction of BW and of the polyester with hexane and tetrahydrofuran, respectively, evidenced that core-double sheath fibers from PEO/polyester/BW/drug consisted of a PEO core, a polyester inner sheath and a BW outer sheath. In order to evaluate the possibility of the application of fibrous materials from PEO/BW/NQ, PEO/PLA/BW/NQ, PEO/PCL/BW/NQ and PEO/PLA/BW/CQ for plant protection, microbiological studies were performed using both phytopathogenic microorganisms (, and ) and beneficial microorganisms (, and ). It was found that the fibrous materials had anti-bacterial and anti-fungal activity against both phytopathogenic and beneficial microorganisms. This is the first report on the activity of fibrous materials loaded with 8-hydroxyquinoline derivatives not only against phytopathogenic but also against beneficial microorganisms that are of importance in agriculture.
PubMed: 37445197
DOI: 10.3390/ma16134882 -
Journal of Agricultural and Food... Jun 2023Phenazine-1-carboxylic acid (PCA) secreted by has been commercialized and widely employed as an antifungal pesticide. However, it displays potential hazards to...
Phenazine-1-carboxylic acid (PCA) secreted by has been commercialized and widely employed as an antifungal pesticide. However, it displays potential hazards to nontarget microorganisms and the environment. Although the PCA degradation characteristics have received extensive attention, the biodegradation efficiency is still insufficient to address the environmental risks. In this study, an engineered capable of degrading PCA was constructed by introducing heterologous PCA 1,2-dioxygenase (PcaA1A2A3A4). By integrating the PCA degradation module in the chemical mutagenesis mutant P3, 7.94 g/L PCA can be degraded in 60 h, which exhibited the highest PCA degradation efficiency to date and was 35.4-fold higher than that of the PCA natural degraders. Additionally, PCA was converted to 1-methoxyphenazine through structure modification by introducing the functional enzymes PhzS and PhzM, which has good antifungal activity and environmental compatibility. This work demonstrates new possibilities for developing PCA-derived biopesticides and enables targeted control of the impact of PCA in diverse environments.
Topics: Pseudomonas chlororaphis; Antifungal Agents; Genetic Engineering; Phenazines; Bacterial Proteins
PubMed: 37247609
DOI: 10.1021/acs.jafc.3c01288 -
Molecules (Basel, Switzerland) Aug 2021In this work, we propose the utilization of scCO to impregnate ibuprofen into the mcl-PHA matrix produced by subs. (DSM 19603). The biopolymer has adhesive properties,...
In this work, we propose the utilization of scCO to impregnate ibuprofen into the mcl-PHA matrix produced by subs. (DSM 19603). The biopolymer has adhesive properties, is biocompatible and has a melting temperature of 45 °C. Several conditions, namely, pressure (15 and 20 MPa) and impregnation time (30 min, 1 h and 3 h) were tested. The highest ibuprofen content (90.8 ± 6.5 mg of ibuprofen/g) was obtained at 20 MPa and 40 °C, for 1 h, with an impregnation rate of 89 mg/(g·h). The processed mcl-PHA samples suffered a plasticization, as shown by the decrease of 6.5 °C in the T, at 20 MPa. The polymer's crystallinity was also affected concomitantly with the matrices' ibuprofen content. For all the impregnation conditions tested the release of ibuprofen from the biopolymer followed a type II release profile. This study has demonstrated that the mcl-PHA produced by has a great potential for the development of novel topical drug delivery systems.
Topics: Adhesiveness; Carbon Dioxide; Drug Carriers; Drug Liberation; Ibuprofen; Polyhydroxyalkanoates; Temperature
PubMed: 34443357
DOI: 10.3390/molecules26164772 -
Microbial Ecology Jul 2023The interaction of plants with bacteria and the long-term success of their adaptation to challenging environments depend upon critical traits that include nutrient...
The interaction of plants with bacteria and the long-term success of their adaptation to challenging environments depend upon critical traits that include nutrient solubilization, remodeling of root architecture, and modulation of host hormonal status. To examine whether bacterial promotion of phosphate solubilization, root branching and the host auxin response may account for plant growth, we isolated and characterized ten bacterial strains based on their high capability to solubilize calcium phosphate. All strains could be grouped into six Pseudomonas species, namely P. brassicae, P. baetica, P. laurylsulfatiphila, P. chlororaphis, P. lurida, and P. extremorientalis via 16S rRNA molecular analyses. A Solibacillus isronensis strain was also identified, which remained neutral when interacting with Arabidopsis roots, and thus could be used as inoculation control. The interaction of Arabidopsis seedlings with bacterial streaks from pure cultures in vitro indicated that their phytostimulation properties largely differ, since P. brassicae and P. laurylsulfatiphila strongly increased shoot and root biomass, whereas the other species did not. Most bacterial isolates, except P. chlororaphis promoted lateral root formation, and P. lurida and P. chlororaphis strongly enhanced expression of the auxin-inducible gene construct DR5:GUS in roots, but the most bioactive probiotic bacterium P. brassicae could not enhance the auxin response. Inoculation with P. brassicae and P. lurida improved shoot and root growth in medium supplemented with calcium phosphate as the sole Pi source. Collectively, our data indicate the differential responses of Arabidopsis seedlings to inoculation with several Pseudomonas species and highlight the potential of P. brassicae to manage phosphate nutrition and plant growth in a more eco-friendly manner.
Topics: Arabidopsis; Pseudomonas; Seedlings; Phosphates; RNA, Ribosomal, 16S; Plant Roots; Indoleacetic Acids; Bacteria
PubMed: 35867140
DOI: 10.1007/s00248-022-02080-y -
Microbial Synthesis of Antibacterial Phenazine-1,6-dicarboxylic Acid and the Role of PhzG in GP72AN.Journal of Agricultural and Food... Feb 2020have been demonstrated to be environmentally friendly biocontrol strains, and most of them can produce phenazine compounds. Phenazine-1,6-dicarboxylic acid (PDC), with...
have been demonstrated to be environmentally friendly biocontrol strains, and most of them can produce phenazine compounds. Phenazine-1,6-dicarboxylic acid (PDC), with a potential antibacterial activity, is generally found in but not in . The present study aimed to explore the feasibility of PDC synthesis and the function of PhzG in . A PDC producer was constructed by replacing in with from . Through gene deletion, common start codon changing, gene silence, and in vitro assay, our result revealed that the yield of PDC in is associated with the relative expression of to and . In addition, it is found that PDC can be spontaneously synthesized without PhzG. This study provides an efficient way for PDC production and promotes a better understanding of PhzG function in PDC biosynthesis. Moreover, this study gives an alternative opportunity for developing new antibacterial biopesticides.
Topics: Amino Acid Sequence; Anti-Bacterial Agents; Bacterial Proteins; Gene Deletion; Molecular Sequence Data; Phenazines; Pseudomonas chlororaphis; Sequence Alignment
PubMed: 32013409
DOI: 10.1021/acs.jafc.9b07657 -
Applied and Environmental Microbiology Mar 2021YL-1 has extensive antimicrobial activities against phytopathogens, and its genome harbors a pyoverdine (PVD) biosynthesis gene cluster. The alternative sigma factor...
YL-1 has extensive antimicrobial activities against phytopathogens, and its genome harbors a pyoverdine (PVD) biosynthesis gene cluster. The alternative sigma factor PvdS in PAO1 acts as a critical regulator in response to iron starvation. The assembly of the PVD backbone starts with peptide synthetase enzyme PvdL. PvdF catalyzes formylation of l-OH-Orn to produce l--hydroxyornithine. Here, we describe the characterization of PVD production in YL-1 and its antimicrobial activity in comparison with that of its PVD-deficient , , and mutants, which were obtained using a -based site-specific mutagenesis strategy. Using methods, we examined the effect of exogenous iron under low-iron conditions and an iron-chelating agent under iron-sufficient conditions on PVD production, antibacterial activity, and the relative expression of the PVD transcription factor gene in YL-1. We found that strain YL-1, the mutant, and the (pUCP26-) complemented strain produced visible PVDs and demonstrated a wide range of inhibitory effects against Gram-negative and Gram-positive bacteria under low-iron conditions and that with the increase of iron, its PVD production and antibacterial activity were reduced. The antibacterial compounds produced by strain YL-1 under low-iron conditions were PVDs based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Moreover, the antibacterial activity observed was correlated with control efficacies of strain YL-1 against rice bacterial leaf blight (BLB) disease caused by pv. oryzae. Collectively, PVDs are responsible for the antibacterial activities of strain YL-1 under both natural and induced low-iron conditions. The results demonstrated that PVDs are essential for the broad-spectrum antibacterial activities of strain YL-1 against both Gram-positive and Gram-negative bacteria under low-iron conditions. Our findings also highlight the effect of exogenous iron on the production of PVD and the importance of this bacterial product in bacterial interactions. As a biocontrol agent, PVDs can directly inhibit the proliferation of the tested bacteria in addition to participating in iron competition.
Topics: Anti-Bacterial Agents; Chromatography, Liquid; Gram-Negative Bacteria; Gram-Positive Bacteria; Iron; Oligopeptides; Pseudomonas chlororaphis; Tandem Mass Spectrometry
PubMed: 33452032
DOI: 10.1128/AEM.02840-20 -
Journal of Applied Microbiology May 2024We aimed to develop an effective bacterial combination that can combat Fusarium oxysporum infection in watermelon using in vitro and pot experiments.
AIMS
We aimed to develop an effective bacterial combination that can combat Fusarium oxysporum infection in watermelon using in vitro and pot experiments.
METHODS AND RESULTS
In total, 53 strains of Bacillus and 4 strains of Pseudomonas were screened. Pseudomonas strains P3 and P4 and Bacillus strains XY-2-3, XY-13, and GJ-1-15 exhibited good antagonistic effects against F. oxysporum. P3 and P4 were identified as Pseudomonas chlororaphis and Pseudomonas fluorescens, respectively. XY-2-3 and GJ-1-15 were identified as B. velezensis, and XY-13 was identified as Bacillus amyloliquefaciens. The three Bacillus strains were antifungal, promoted the growth of watermelon seedlings and had genes to synthesize antagonistic metabolites such as bacilysin, surfactin, yndj, fengycin, iturin, and bacillomycin D. Combinations of Bacillus and Pseudomonas strains, namely, XY-2-3 + P4, GJ-1-15 + P4, XY-13 + P3, and XY-13 + P4, exhibited a good compatibility. These four combinations exhibited antagonistic effects against 11 pathogenic fungi, including various strains of F. oxysporum, Fusarium solani, and Rhizoctonia. Inoculation of these bacterial combinations significantly reduced the incidence of Fusarium wilt in watermelon, promoted plant growth, and improved soil nutrient availability. XY-13 + P4 was the most effective combination against Fusarium wilt in watermelon with the inhibition rate of 78.17%. The number of leaves; aboveground fresh and dry weights; chlorophyll, soil total nitrogen, and soil available phosphorus content increased by 26.8%, 72.12%, 60.47%, 16.97%, 20.16%, and 16.50%, respectively, after XY-13 + P4 inoculation compared with the uninoculated control. Moreover, total root length, root surface area, and root volume of watermelon seedlings were the highest after XY-13 + P3 inoculation, exhibiting increases by 265.83%, 316.79%, and 390.99%, respectively, compared with the uninoculated control.
CONCLUSIONS
XY-13 + P4 was the best bacterial combination for controlling Fusarium wilt in watermelon, promoting the growth of watermelon seedlings, and improving soil nutrient availability.
Topics: Fusarium; Citrullus; Plant Diseases; Bacillus; Disease Resistance; Pseudomonas; Antibiosis; Pseudomonas fluorescens; Seedlings; Antifungal Agents
PubMed: 38632051
DOI: 10.1093/jambio/lxae074 -
Biotechnology and Bioengineering Nov 2019Cinnabarinic acid is a valuable phenoxazinone that has broad applications in the pharmaceutical, chemical, and dyeing industries. However, few studies have investigated...
Cinnabarinic acid is a valuable phenoxazinone that has broad applications in the pharmaceutical, chemical, and dyeing industries. However, few studies have investigated the production of cinnabarinic acid or its derivatives using genetically engineered microorganisms. Herein, an efficient synthetic pathway of cinnabarinic acid was designed and constructed in Pseudomonas chlororaphis GP72 for the first tim, which was more straightforward and robust than the known eukaryotic biosynthetic pathways. First, we screened and identified trans-2,3-dihydro-3-hydroxyanthranilic acid (DHHA) dehydrogenases from Escherichia coli MG1655 (encoded by entA), Streptomyces sp. NRRL12068 (encoded by bomO) and Streptomyces chartreusis NRRL3882 (encoded by calB ) based on the structural similarity of the substrate and product, and the DHHA dehydrogenase encoded by calB was selected for the synthesis of cinnabarinic acid due to its high DHHA conversion rate. Subsequently, cinnabarinic acid was synthesized by the expression of the DHHA dehydrogenase CalB and the phenoxazinone synthase CotA in the DHHA-producing strain P. chlororaphis GP72, resulting in a cinnabarinic acid titer of 20.3 mg/L at 48 hr. Further fermentation optimization by the addition of Cu , H O , and with adding glycerol increased cinnabarinic acid titer to 136.2 mg/L in shake flasks. The results indicate that P. chlororaphis GP72 may be engineered as a microbial cell factory to produce cinnabarinic acid or its derivatives from renewable bioresources.
Topics: Bacterial Proteins; Biosynthetic Pathways; Gene Expression Regulation, Bacterial; Metabolic Engineering; Oxazines; Pseudomonas chlororaphis
PubMed: 31317529
DOI: 10.1002/bit.27118