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Microorganisms Jul 2023Causing major health and ecological disturbances, polychlorinated biphenyls (PCBs) are persistent organic pollutants still recovered all over the world. Microbial PCB...
Causing major health and ecological disturbances, polychlorinated biphenyls (PCBs) are persistent organic pollutants still recovered all over the world. Microbial PCB biotransformation is a promising technique for depollution, but the involved molecular mechanisms remain misunderstood. Ligninolytic enzymes are suspected to be involved in many PCB transformations, but their assessments remain scarce. To further inventory the capabilities of microbes to transform PCBs through their ligninolytic enzymes, we investigated the role of oxidase and peroxidase among a set of microorganisms isolated from a historically PCB-contaminated site. Among 29 isolated fungi and 17 bacteria, this work reports for the first time the PCB-transforming capabilities from fungi affiliated to , , , , , , and genera and bacteria affiliated to , , , , , sp., , and . In the same way, this is the first report of fungal isolates affiliated to the specie and genus that displayed oxidase (putatively laccase) and peroxidase activity, respectively, enhanced in the presence of PCBs (more than 4-fold and 20-fold, respectively, compared to controls). Based on these results, the observed activities are suspected to be involved in PCB transformation.
PubMed: 37630447
DOI: 10.3390/microorganisms11081887 -
Environmental Science & Technology Aug 2023Plant growth promoting rhizobacteria (PGPR) produce extracellular reactive oxygen species (ROS) to protect plants from external stresses. Fe-based nanomaterials can...
Plant growth promoting rhizobacteria (PGPR) produce extracellular reactive oxygen species (ROS) to protect plants from external stresses. Fe-based nanomaterials can potentially interact with PGPR and synergistically degrade organic pollutants, yet they have received no study. Here, we studied how the interaction between a typical PGPR (, JD37) and Fe-based nanomaterials facilitated the degradation of 2,4,4'-trichlorobiphenyl (PCB28), by comparing the zerovalent iron of 20 nm (nZVI), 100 nm (nZVI), and 5 μm; iron oxide nanomaterials (α-FeO, γ-FeO, and FeO) of ca. 20 nm; and ferrous and ferric salts. Although all Fe materials (0.1 g L) alone could not degrade aqueous PCB28 (0.1 mg L) under dark or aerobic conditions, nZVI, nZVI, α-FeO, and Fe promoted PCB28 degradation by JD37, with the half-life of PCB28 shortened from 16.5 h by JD37 alone to 8.1 h with nZVI cotreatment. Mechanistically, the nanomaterials stimulated JD37 to secrete phenazine-1-carboxylic acid and accelerated the NADH/NAD conversion, promoting O generation; JD37 increased Fe(II) dissolution from the nanomaterials, facilitating *OH generation; and the ROS gradually degraded PCB28 into benzoic acid through dihydroxy substitution, oxidation to quinone, and Michael addition. These findings provide a new strategy of nanoenabled biodegradation of organic pollutants by applying Fe-based nanomaterials and PGPR.
Topics: Polychlorinated Biphenyls; Reactive Oxygen Species; Iron; Nanostructures; Environmental Pollutants
PubMed: 37583057
DOI: 10.1021/acs.est.3c02495 -
World Journal of Microbiology &... Aug 2023Phenazines are heteroaromatic compounds consisting of a central pyrazine ring fused with two benzenes. Different functional groups attached to the dibenzopyrasin core...
Phenazines are heteroaromatic compounds consisting of a central pyrazine ring fused with two benzenes. Different functional groups attached to the dibenzopyrasin core cause differences in the chemical, physical, and biological properties of phenazines. Interest in these compounds has not diminished for decades. New biological activities and practical applications discovered in recent years force researchers to investigate all aspects of the synthesis, degradation, and mechanisms of action of phenazines. In this study, we have demonstrated the involvement of the coxA gene product (cytochrome c oxidase, su I) in the production of phenazines in P. chlororaphis subsp. aurantiaca. Overlap PCR was used to knock out the coxA gene and the resulting mutants were screened for their ability to grow on rich and minimal culture media and for phenazine production. The reintroduction of the full-length coxA gene into the B-162/coxA strains was used to further confirm the role of this gene product in the ability to produce phenazines. We were able to show that the product of the coxA gene is necessary for phenazine production in rich growth media. At the same time, the CoxA protein does not seem to have any effect on phenazine production in M9 minimal salt medium. We could show that knocking down even one subunit of the cytochrome c oxidase complex leads to a significant reduction (to trace concentrations) or complete suppression of phenazine antibiotic production on rich PCA medium in P. chlororaphis subsp. aurantiaca.
Topics: Electron Transport Complex IV; Pseudomonas; Phenazines; Bacterial Proteins
PubMed: 37583000
DOI: 10.1007/s11274-023-03685-2 -
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 -
Letters in Applied Microbiology Jul 2023The use of microbial consortia has become a promising alternative for the management of various diseases. In this study, 18 artificial consortia were designed,...
The use of microbial consortia has become a promising alternative for the management of various diseases. In this study, 18 artificial consortia were designed, consisting of five bacteria, five fungi, and a mixture of five fungi and five bacteria; from a collection of microorganisms isolated from the rhizosphere of cape gooseberry plants grown in two soils potentially suppressive against Fusarium oxysporum. When evaluated under greenhouse conditions for their biocontrol activity on cape gooseberry plants, one consortium was selected for their high efficacy (over 90%) in the control of vascular wilt caused by F. oxysporum f. sp. physali. This was constituted by 10 microorganisms, the bacteria Paenibacillus peoriae, Bacillus subtilis, Lysinibacillus sp., B. simplex, and Pseudomonas chlororaphis; and the fungi Beauveria bassiana, Scopulariopsis brevicaulis, Trichoderma gamsii, T. ghanense, and T. lignicola. On the other hand, four of the consortia evaluated in the presence of the pathogen mitigated the deleterious effect produced by the pathogen on plant growth, expressing higher dry weights, both in the aerial and root parts. This work represents the first report on using these mixtures of microorganisms to control vascular wilt produced by F. oxysporum. However, further studies are needed to determine their activity in cape gooseberry fields.
Topics: Fusarium; Microbial Consortia; Ribes; Physalis; Bacillus subtilis; Fungi; Plant Diseases
PubMed: 37348479
DOI: 10.1093/lambio/ovad072 -
Angewandte Chemie (International Ed. in... Jul 2023A non-canonical biosynthetic pathway furnishing the first natural brexane-type bishomosesquiterpene (chlororaphen, C H ) was elucidated in the γ-proteobacterium...
Non-canonical Biosynthesis of the Brexane-Type Bishomosesquiterpene Chlororaphen through Two Consecutive Methylation Steps in Pseudomonas chlororaphis O6 and Variovorax boronicumulans PHE5-4.
A non-canonical biosynthetic pathway furnishing the first natural brexane-type bishomosesquiterpene (chlororaphen, C H ) was elucidated in the γ-proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three-step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C ) along with cyclization and ring contraction to furnish monocyclic γ-presodorifen pyrophosphate (γ-PSPP, C ). Subsequent C-methylation of γ-PSPP by a second C-methyltransferase furnishes the monocyclic α-prechlororaphen pyrophosphate (α-PCPP, C ), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β-proteobacterium Variovorax boronicumulans PHE5-4, demonstrating that non-canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
Topics: Methylation; Pseudomonas chlororaphis; Diphosphates; Comamonadaceae
PubMed: 37132448
DOI: 10.1002/anie.202303692 -
Microbial Ecology Oct 2023Combining different biocontrol agents (BCA) is an approach to increase efficacy and reliability of biological control. If several BCA are applied together, they have to...
Combining different biocontrol agents (BCA) is an approach to increase efficacy and reliability of biological control. If several BCA are applied together, they have to be compatible and ideally work together. We studied the interaction of a previously selected BCA consortium of entomopathogenic pseudomonads (Pseudomonas chlororaphis), nematodes (Steinernema feltiae associated with Xenorhabdus bovienii), and fungi (Metarhizium brunneum). We monitored the infection course in a leaf- (Pieris brassicae) and a root-feeding (Diabrotica balteata) pest insect after simultaneous application of the three BCA as well as their interactions inside the larvae in a laboratory setting. The triple combination caused the highest mortality and increased killing speed compared to single applications against both pests. Improved efficacy against P. brassicae was mainly caused by the pseudomonad-nematode combination, whereas the nematode-fungus combination accelerated killing of D. balteata. Co-monitoring of the three BCA and the nematode-associated Xenorhabdus symbionts revealed that the four organisms are able to co-infect the same larva. However, with advancing decay of the cadaver there is increasing competition and cadaver colonization is clearly dominated by the pseudomonads, which are known for their high competitivity in the plant rhizosphere. Altogether, the combination of the three BCA increased killing efficacy against a Coleopteran and a Lepidopteran pest which indicates that this consortium could be applied successfully against a variety of insect pests.
Topics: Animals; Reproducibility of Results; Pest Control, Biological; Insecta; Larva; Rhabditida; Plant Leaves
PubMed: 36849610
DOI: 10.1007/s00248-023-02191-0 -
Folia Microbiologica Aug 2023Volatile compounds emitted by bacteria can play a significant role in interacting with microorganisms, plants, and other organisms. In this work, we studied the effect...
Volatile compounds emitted by bacteria can play a significant role in interacting with microorganisms, plants, and other organisms. In this work, we studied the effect of total gaseous mixtures of organic as well as inorganic volatile compounds (VCs) and individual pure volatile organic compounds (VOCs: ketones 2-nonanone, 2-heptanone, 2-undecanone, a sulfur-containing compound dimethyl disulfide) synthesized by the rhizosphere Pseudomonas chlororaphis 449 and Serratia plymuthica IC1270 strains, the soil-borne strain P. fluorescens B-4117, and the spoiled meat isolate S. proteamaculans 94 strain on Arabidopsis thaliana plants (on growth and germination of seeds). We demonstrated that total mixtures of volatile compounds emitted by these strains grown on Luria-Bertani agar, Tryptone Soya Agar, and Potato Dextrose Agar media inhibited the A. thaliana growth. When studied bacteria grew on Murashige and Skoog (MS) agar medium, volatile mixtures produced by bacteria could stimulate the growth of plants. Volatile compounds of bacteria slowed down the germination of plant seeds; in the presence of volatile mixtures of P. fluorescens B-4117, the seeds did not germinate. Of the individual VOCs, 2-heptanone had the most potent inhibitory effect on seed germination. We also showed that the tested VOCs did not cause oxidative stress in Escherichia coli cells using specific lux-biosensors. VOCs reduced the expression of the lux operon from the promoters of the katG, oxyS, and soxS genes (whose products involved in the protection of cells from oxidative stress) caused by the action of hydrogen peroxide and paraquat, respectively.
Topics: Pseudomonas; Agar; Escherichia coli; Serratia; Volatile Organic Compounds
PubMed: 36790684
DOI: 10.1007/s12223-023-01038-y -
Microbial Ecology Aug 2023Aquaponics is defined as a sustainable and integrated system that combines fish aquaculture and hydroponic plant production in the same recirculated water loop. A recent...
First Study Case of Microbial Biocontrol Agents Isolated from Aquaponics Through the Mining of High-Throughput Sequencing Data to Control Pythium aphanidermatum on Lettuce.
Aquaponics is defined as a sustainable and integrated system that combines fish aquaculture and hydroponic plant production in the same recirculated water loop. A recent study using high-throughput sequencing (HTS) technologies highlighted that microbial communities from an aquaponic system could control one of the most problematic pathogens in soilless lettuce culture, namely, Pythium aphanidermatum. Therefore, this study aims at isolating the microorganisms responsible for this biocontrol action. Based on the most promising genera identified by HTS, an innovative strategy for isolating and testing original biocontrol agents from aquaponic water was designed to control P. aphanidermatum. Eighty-two bacterial strains and 18 fungal strains were isolated, identified by Sanger sequencing, and screened in vivo to control damping-off of lettuce seeds caused by P. aphanidermatum. Out of these 100 isolates, the eight most efficacious ones were selected and further tested individually to control root rot disease caused by the same pathogen at a later stage of lettuce growth. Strains SHb30 (Sphingobium xenophagum), G2 (Aspergillus flavus), and Chito13 (Mycolicibacterium fortuitum) decreased seed damping-off at a better rate than a propamocarb fungicide and a Pseudomonas chlororaphis registered biocontrol agent did. In root rot bioassays, lettuce mortality was prevented by applying strains G2 and Chito13, which were at least as efficacious as the fungicide or biopesticide controls. Lettuce disease symptoms and mortality were eradicated by strain SHb30 in the first bioassay, but not in the second one. These results show that aquaponic systems are promising sources of original biocontrol agents, and that HTS-guided strategies could represent interesting approaches to identify new biocontrol agents.
Topics: Animals; Fungicides, Industrial; Pythium; Lactuca; Pest Control, Biological; Plant Diseases; Water; High-Throughput Nucleotide Sequencing
PubMed: 36334118
DOI: 10.1007/s00248-022-02126-1