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Microbiological Research Oct 2020Three morphological mutants (M71a, M71b, M71c) of the antagonist Pseudomonas chlororaphis M71, naturally arose during a biocontrol trial against the phytopathogenic...
Three morphological mutants (M71a, M71b, M71c) of the antagonist Pseudomonas chlororaphis M71, naturally arose during a biocontrol trial against the phytopathogenic fungus Fusarium oxysporum f.sp. radicis-lycopersisci. In this study, the three mutants were investigated to elucidate their role in the biocontrol of plant pathogens. M71a and M71b phenotypes were generated by a mutation in the two-component system GacS/GacA. The mutation determined an increase in siderophore production and an impaired ability to release proteases, to swarm, to produce phenazine and AHLs and to colonize tomato roots. In vitro antagonistic activity against different plant pathogens was partially reduced in M71a, while M71b resulted effective only against Pythium ultimum. Biocontrol efficacy against Fusarium oxysporum f.sp. radicis-lycopersisci, was partially reduced in M71a and completely lost in M71b. M71c phenotype was impaired in swarming motility, did not produce biofilms and its antagonistic activity was similar to the parental M71 strain. M71c showed an enhanced ability to colonize tomato roots, on which its progeny in part reverted to the M71 parental phenotype. Volatile organic compounds (VOCs) emitted by all four strains, inhibited the growth of Clavibacter michiganensis subsp. michiganensis and Seiridium cardinale in vitro. Real-time screening of VOCs by PTR-MS combined with GC-MS analysis, showed that methanethiol was the main component of the blend produced by all four M71 strains. However, the emissions of hydrogen cyanide, dimethyl disulfide, 1,3-butadiene and acetone were significantly affected by the three different mutations. These findings highlight that the simultaneous presence of different M71 phenotypes may improve, through the integration of different mechanisms, the ecological fitness and biocontrol efficacy of P. chlororaphis M71.
Topics: Bacterial Proteins; Biological Control Agents; Fusarium; Solanum lycopersicum; Mutation; Pest Control, Biological; Phenazines; Phenotype; Plant Diseases; Plant Roots; Pseudomonas chlororaphis; Siderophores; Volatile Organic Compounds
PubMed: 32535393
DOI: 10.1016/j.micres.2020.126517 -
New Pseudomonas Bacterial Strains: Biological Activity and Characteristic Properties of Metabolites.Microorganisms Jul 2023This paper investigates the antagonistic and plant growth promotion activity of the new indigenous bacteria antagonist strains BZR 245-F and sp. BZR 523-2. It was...
This paper investigates the antagonistic and plant growth promotion activity of the new indigenous bacteria antagonist strains BZR 245-F and sp. BZR 523-2. It was found that on the 10th day of cultivation, BZR 245-F and BZR 523-2 exhibit an antagonistic activity against at the level of 59.6% and 15.1% and against var. at the level of 50.2% and 8.9%, respectively. Furthermore, the BZR 523-2 strain stimulated the growth of winter wheat seedlings more actively than the BZR 245-F strain. When processing seeds of winter wheat, sp. BZR 523-2 indicators were higher than in the control: plant height increased by 10.3%, and root length increased by 18.6%. The complex characteristic properties of the metabolite were studied by bioautography and HPLC-MS. Bioautography proved the antifungal activity of phenazine nature compounds synthesized by the new bacterial strains. We qualitatively and quantitatively analyzed them by HPLC-MS analysis of the strain sample metabolites. In the BZR 245-F sample, we found more phenazine compounds of various types. Their total phenazine concentration in the BZR 245-F was more than five times greater than in the BZR 523-2. We defined crucial differences in the quantitative content of the other metabolites. Despite the difference between new indigenous bacteria antagonist strains, they can be used as producers of effective biopesticides for sustainable agriculture management.
PubMed: 37630503
DOI: 10.3390/microorganisms11081943 -
Frontiers in Microbiology 2022Vaginal and cervical canal bacteria are associated with women's health and pregnancy outcomes. Here, we compared their composition and characteristics in 37...
Vaginal and cervical canal bacteria are associated with women's health and pregnancy outcomes. Here, we compared their composition and characteristics in 37 reproductive-aged Chinese women including 24 pregnant women with cervical incompetence (vaginal and cervical canal bacteria formed Groups A and B, respectively) and 13 healthy pregnant women (vaginal and cervical canal bacteria formed Groups C and D, respectively) using high-throughput sequencing of the V4 region of 16S rRNA gene. The results of alpha and beta diversity analysis, respectively, indicated no statistical differences between Groups A and B ( = 0.32, 0.06), nor Groups B and D ( = 0.69, 0.74); however, differences were found between Groups C and D ( = 0.02, 0.01) and between Groups A and C ( = 0.04, 0.02). PLS-DA analysis showed that the individuals from each group were irregularly distributed according to their clade. , and were the dominant genera in all groups. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSts) analysis identified 31 Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologs associated with the bacterial communities from the four groups, including membrane transport, folding, sorting and degradation, xenobiotics biodegradation and metabolism, and nucleotide metabolism. We further determined relationships between pregnancy outcomes (Apgar scores) and certain bacterial species. A significant positive correlation was found between Apgar scores and and in the vagina and cervical canal of pregnant women with cervical incompetence while , and in the cervical canal displayed negative correlations with Apgar scores. Moreover, , , and in the vagina were negatively correlated with Apgar scores. These bacteria may serve as potential biomarkers, however, additional research is warranted to verify their role in clinical outcomes.
PubMed: 36246259
DOI: 10.3389/fmicb.2022.986326 -
Biology Jan 2022DAHP synthase catalyzes the first step in the shikimate pathway, deriving the biosynthesis of aromatic amino acids (Trp, Phe and Tyr), phenazine-1-carboxamide, folic...
DAHP synthase catalyzes the first step in the shikimate pathway, deriving the biosynthesis of aromatic amino acids (Trp, Phe and Tyr), phenazine-1-carboxamide, folic acid, and ubiquinone in . In this study, we identified and characterized one DAHP synthase encoding gene , which differs from the reported DAHP synthase encoding genes , and in . . PhzC accounts for approximately 90% of the total DAHP synthase activities in . HT66 and plays the most critical role in four DAHP synthases in the shikimate pathway. Inactivation of resulted in the reduction of PCN production by more than 90%, while the absence of genes , and reduced PCN yield by less than 15%, and the production of PCN was restored after the complementation of gene . Moreover, the results showed that in . HT66 is not sensitive to feedback inhibition. This study demonstrated that gene is essential for PCN biosynthesis. The expression level of both and genes are not inhibited in feedback by PCN production due to the absence of a loop region required for allosteric control reaction. This study highlighted the importance of PhzC and applying . for shikimate pathway-derived high-value biological production.
PubMed: 35053084
DOI: 10.3390/biology11010086 -
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 -
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 -
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 -
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 -
Biology Sep 2023Phenazine compounds are widely used in agricultural control and the medicine industry due to their high inhibitory activity against pathogens and antitumor activity. The...
Phenazine compounds are widely used in agricultural control and the medicine industry due to their high inhibitory activity against pathogens and antitumor activity. The green and sustainable method of synthesizing phenazine compounds through microbial fermentation often requires a complex culture medium containing tryptone and yeast extract, and its cost is relatively high, which greatly limits the large-scale industrial production of phenazine compounds by fermentation. The aim of this study was to develop a cost-effective minimal medium for the efficient synthesis of phenazine compounds by . Through testing the minimum medium commonly used by , an ME medium for with a high production of phenazine compounds was obtained. Then, the components of the ME medium and the other medium were compared and replaced to verify the beneficial promoting effect of Fe and NH on phenazine compounds. A cost-effective general defined medium (GDM) using glycerol as the sole carbon source was obtained by optimizing the composition of the ME medium. Using the GDM, the production of phenazine compounds by reached 1073.5 mg/L, which was 1.3 times that achieved using a complex medium, while the cost of the GDM was only 10% that of a complex medium (e.g., the KB medium). Finally, by engineering the glycerol metabolic pathway, the titer of phenazine-1-carboxylic acid reached the highest level achieved using a minimum medium so far. This work demonstrates how we systematically analyzed and optimized the composition of the medium and integrated a metabolic engineering method to obtain the most cost-effective fermentation strategy.
PubMed: 37887002
DOI: 10.3390/biology12101292 -
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