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The ISME Journal Oct 2023Proteobacteria primarily utilize acyl-homoserine lactones (AHLs) as quorum-sensing signals for intra-/interspecies communication to control pathogen infections....
Proteobacteria primarily utilize acyl-homoserine lactones (AHLs) as quorum-sensing signals for intra-/interspecies communication to control pathogen infections. Enzymatic degradation of AHL represents the major quorum-quenching mechanism that has been developed as a promising approach to prevent bacterial infections. Here we identified a novel quorum-quenching mechanism revealed by an effector of the type IVA secretion system (T4ASS) in bacterial interspecies competition. We found that the soil antifungal bacterium Lysobacter enzymogenes OH11 (OH11) could use T4ASS to deliver the effector protein Le1288 into the cytoplasm of another soil microbiome bacterium Pseudomonas fluorescens 2P24 (2P24). Le1288 did not degrade AHL, whereas its delivery to strain 2P24 significantly impaired AHL production through binding to the AHL synthase PcoI. Therefore, we defined Le1288 as LqqE1 (Lysobacter quorum-quenching effector 1). Formation of the LqqE1-PcoI complex enabled LqqE1 to block the ability of PcoI to recognize/bind S-adenosy-L-methionine, a substrate required for AHL synthesis. This LqqE1-triggered interspecies quorum-quenching in bacteria seemed to be of key ecological significance, as it conferred strain OH11 a better competitive advantage in killing strain 2P24 via cell-to-cell contact. This novel quorum-quenching also appeared to be adopted by other T4ASS-production bacteria. Our findings suggest a novel quorum-quenching that occurred naturally in bacterial interspecies interactions within the soil microbiome by effector translocation. Finally, we presented two case studies showing the application potential of LqqE1 to block AHL signaling in the human pathogen Pseudomonas aeruginosa and the plant pathogen Ralstonia solanacearum.
Topics: Humans; Quorum Sensing; Bacterial Proteins; Pseudomonas; Pseudomonas aeruginosa; Acyl-Butyrolactones; Pseudomonas fluorescens
PubMed: 37340074
DOI: 10.1038/s41396-023-01457-2 -
Biology Letters Mar 2022Interactions between microbes can both constrain and enhance their adaptation to the environment. However, most studies to date have employed simplified microbial...
Interactions between microbes can both constrain and enhance their adaptation to the environment. However, most studies to date have employed simplified microbial communities and environmental conditions. We determined how the presence of a commercial potting compost microbial community affected adaptation of the soil bacterium SBW25 in potting compost. clones isolated from populations evolved in both the presence and absence of the community showed similar fitness increases when measured in the absence of the community. This suggests the presence of the community did not constrain adaptation. By contrast, fitness measured in the presence of the community increased for community-evolved populations, but decreased below the ancestral state for populations evolved in the absence of the community. This suggests some, but not all, mutations that were beneficial with respect to the abiotic environment were costly in the presence of the community, with the former selected against in the presence of the community. Whole-genome sequencing supports this interpretation: most mutations underpinning fitness changes were clone-specific, suggesting multiple genetic pathways to adaptation. Such extreme mutational effects have not been observed in comparable studies, suggesting that caution is needed when extrapolating results from simplified systems to natural contexts.
Topics: Acclimatization; Adaptation, Physiological; Pseudomonas fluorescens; Soil; Soil Microbiology
PubMed: 35259940
DOI: 10.1098/rsbl.2021.0593 -
Plant Signaling & Behavior Dec 2022An endophytic (BsEB-1) was obtained from the roots of . We investigated its growth-promoting properties and observed the impact of its inoculation on both the growth...
An endophytic (BsEB-1) was obtained from the roots of . We investigated its growth-promoting properties and observed the impact of its inoculation on both the growth and polysaccharide content of tubers. It was found that BsEB-1 possessed three growth-promoting activities: phosphate-solubilizing, produced indoleacetic acid (IAA) and siderophores, but had no nitrogen-fixing activity. BsEB-1 could rapidly attach to the root hairs of tissue culture seedlings and endophytically colonize the region of maturation in the roots. It also significantly promoted the rooting and transplant survival rate of the seedlings, as well as the growth and expansion of the tubers, but did not increase their polysaccharide content. BsEB-1 exhibits potential for applications in the artificial planting of
Topics: Orchidaceae; Plant Tubers; Polysaccharides; Pseudomonas fluorescens; Seedlings
PubMed: 35922084
DOI: 10.1080/15592324.2022.2100626 -
The Journal of General and Applied... Sep 2017The tea mosquito bug (TMB), Helopeltis spp. (Hemiptera: Miridae) is an insidious pest that poses a significant economical threat to tea plantations. Pseudomonas cultures...
The tea mosquito bug (TMB), Helopeltis spp. (Hemiptera: Miridae) is an insidious pest that poses a significant economical threat to tea plantations. Pseudomonas cultures are being used extensively for pest management which, however, resulting in a low mortality rate of insects and which has prompted us to search for a new microbial metabolite for TMB control. A chitinase purified from P. fluorescens and partially characterized by our group showed insecticidal activity against TMB. The mode of action behind chitinase toxicity is the enzymatic hydrolysis of chitin, which is a common constituent of the insect exoskeleton and gut lining of the peritrophic membrane. A chitinase-secreting strain MP-13 was characterized based on 16S rRNA sequencing and validated as Pseudomonas fluorescens. In the present study, purified chitinase (0.048 units/ml) enzyme from P. fluorescens MP-13 revealed 100% TMB mortality under in-vitro conditions. The results of this study can be utilized for future crop improvement programs and integrated pest management strategies.
Topics: Animals; Bacterial Proteins; Chitin; Chitinases; Heteroptera; Insecticides; Pest Control, Biological; Pseudomonas fluorescens; RNA, Ribosomal, 16S
PubMed: 28680004
DOI: 10.2323/jgam.2016.11.001 -
Molecules (Basel, Switzerland) Sep 20193-Carene is an antimicrobial monoterpene that occurs naturally in a variety of plants and has an ambiguous antibacterial mechanism against food-borne germs. The...
3-Carene is an antimicrobial monoterpene that occurs naturally in a variety of plants and has an ambiguous antibacterial mechanism against food-borne germs. The antibacterial effects and action mechanism of 3-carene against Gram-positive ACCC 03870 and Gram-negative ATCC 13525 were studied. Scanning electron microscopy (SEM) examination and leakage of alkaline phosphatase (AKP) verified that 3-carene caused more obvious damage to the morphology and wall structure of than . The release of potassium ions and proteins, the reduction in membrane potential (MP), and fluorescein diacetate (FDA) staining further confirmed that the loss of the barrier function of the cell membrane and the leakage of cytoplasmic contents were due to the 3-carene treatment. Furthermore, the disorder of succinate dehydrogenase (SDH), malate dehydrogenase (MDH), pyruvate kinase (PK), and ATP content indicated that 3-carene could lead to metabolic dysfunction and inhibit energy synthesis. In addition, the results from the fluorescence analysis revealed that 3-carene could probably bind to bacterial DNA and affect the conformation and structure of genomic DNA. These results revealed that 3-carene had strong antibacterial activity against and via membrane damage, bacterial metabolic perturbations, and genomic DNA structure disruption, interfering in cellular functions and even causing cell death.
Topics: Anti-Bacterial Agents; Bicyclic Monoterpenes; Brochothrix; Cell Wall; DNA, Bacterial; Food Microbiology; Membrane Potentials; Microbial Sensitivity Tests; Microscopy, Electron, Scanning; Pseudomonas fluorescens
PubMed: 31489899
DOI: 10.3390/molecules24183246 -
Microbiology Spectrum Apr 2022The genus Pseudomonas, a complex Gram-negative genus, includes species isolated from various environments, plants, animals, and humans. We compared whole-genome...
The genus Pseudomonas, a complex Gram-negative genus, includes species isolated from various environments, plants, animals, and humans. We compared whole-genome sequencing (WGS) with clinical bacteriological methods and evaluated matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify Pseudomonas species. Clinical isolates ( = 42) identified as P. putida or P. fluorescens by a bacterial identification system based on biochemical properties were reexamined by another identification system based on biochemical properties, two systems based on MALDI-TOF MS, and WGS. WGS revealed that 30 of the 42 isolates belonged to one of 14 known Pseudomonas species, respectively. The remaining 12 belonged to one of 9 proposed novel Pseudomonas species, respectively. MALDI-TOF MS analysis showed that the 9 novel species had unique major peaks. These results suggest that WGS is the optimal method to identify Pseudomonas species and that MALDI-TOF MS may complement WGS in identification. Based on their morphologic, physiologic, and biochemical properties, we propose nine novel Pseudomonas species. Most of the clinical isolates, identified as P. putida or P. fluorescens, were misidentified in clinical laboratories. Whole-genome sequencing (WGS) revealed that these isolates belonged to different Pseudomonas species, including novel species. WGS is a gold-standard method to identify Pseudomonas species, and MALDI-TOF MS analysis has the potential to complement WGS to reliably identify them.
Topics: Animals; Bacteriological Techniques; Pseudomonas fluorescens; Pseudomonas putida; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Whole Genome Sequencing
PubMed: 35389240
DOI: 10.1128/spectrum.02491-21 -
Journal of Dairy Science Sep 2018Postpasteurization contamination (PPC) of high temperature, short time-pasteurized fluid milk by gram-negative (GN) bacteria continues to be an issue for processors. To...
Postpasteurization contamination (PPC) of high temperature, short time-pasteurized fluid milk by gram-negative (GN) bacteria continues to be an issue for processors. To improve PPC control, a better understanding of PPC patterns in dairy processing facilities over time and across equipment is needed. We thus collected samples from 10 fluid milk processing facilities to (1) detect and characterize PPC patterns over time, (2) determine the efficacy of different media to detect PPC, and (3) characterize sensory defects associated with PPC. Specifically, we collected 280 samples of high temperature, short time-pasteurized milk representing different products (2%, skim, and chocolate) and different fillers over 4 samplings performed over 11 mo at each of the 10 facilities. Standard plate count (SPC) as well as total GN, coliform, and Enterobacteriaceae (EB) counts were performed upon receipt and after 7, 10, 14, 17, and 21 d of storage at 6°C. We used 16S rDNA sequencing to characterize representative bacterial isolates from (1) test days with SPC >20,000 cfu/mL and (2) all samples with presumptive GN, coliforms, or EB. Day-21 samples were also evaluated by a trained defect judging panel. By d 21, 226 samples had SPC >20,000 cfu/mL on at least 1 d of shelf life; GN bacteria were found in 132 of these 226 samples, indicating PPC. Crystal violet tetrazolium agar detected PPC with the greatest sensitivity. Spoilage due to PPC was predominantly associated with Pseudomonas (isolated from 101 of the 132 samples with PPC); coliforms and EB were found in 27 and 37 samples with spoilage due to PPC, respectively. Detection of Pseudomonas and Acinetobacter was associated with lower flavor scores; coagulated, fruity fermented, and unclean defects were more prevalent in d-21 samples with PPC. Repeat isolation of Pseudomonas fluorescens group strains with identical partial 16S rDNA sequence types was observed in 8 facilities. In several facilities, specific lines, products, or processing days were linked to repeat product contamination with Pseudomonas with identical sequence types. Our data show that PPC due to Pseudomonas remains a major challenge for fluid milk processors; the inability of coliform and EB tests to detect Pseudomonas may contribute to this. Our data also provide important initial insights into PPC patterns (e.g., line-specific contamination), supporting the importance of molecular subtyping methods for identification of PPC sources.
Topics: Animals; Colony Count, Microbial; Enterobacteriaceae; Food Contamination; Food Microbiology; Food Preservation; Milk; Pseudomonas; Pseudomonas fluorescens; Taste
PubMed: 29960782
DOI: 10.3168/jds.2018-14438 -
Molecules (Basel, Switzerland) Nov 2019The arylacetonitrilase from the bacterium EBC191 has been intensively studied as a model to understand the molecular basis for the substrate-, reaction-, and... (Comparative Study)
Comparative Study Review
The arylacetonitrilase from the bacterium EBC191 has been intensively studied as a model to understand the molecular basis for the substrate-, reaction-, and enantioselectivity of nitrilases. The nitrilase converts various aromatic and aliphatic nitriles to the corresponding acids and varying amounts of the corresponding amides. The enzyme has been analysed by site-specific mutagenesis and more than 50 different variants have been generated and analysed for the conversion of (,)-mandelonitrile and (,)-2-phenylpropionitrile. These comparative analyses demonstrated that single point mutations are sufficient to generate enzyme variants which hydrolyse (,)-mandelonitrile to ()-mandelic acid with an enantiomeric excess (ee) of 91% or to ()-mandelic acid with an ee-value of 47%. The conversion of (,)-2-phenylpropionitrile by different nitrilase variants resulted in the formation of either ()- or ()-2-phenylpropionic acid with ee-values up to about 80%. Furthermore, the amounts of amides that are produced from (,)-mandelonitrile and (,)-2-phenylpropionitrile could be changed by single point mutations between 2%-94% and <0.2%-73%, respectively. The present study attempted to collect and compare the results obtained during our previous work, and to obtain additional general information about the relationship of the amide forming capacity of nitrilases and the enantiomeric composition of the products.
Topics: Acetonitriles; Aminohydrolases; Mutation; Pseudomonas fluorescens; Substrate Specificity
PubMed: 31766372
DOI: 10.3390/molecules24234232 -
Molecules (Basel, Switzerland) Jun 2024In this study, hybrid skeleton material ZIF-8@ZIF-67 was synthesized by the epitaxial growth method and then was utilized as a carrier for encapsulating lipase (PFL)...
In this study, hybrid skeleton material ZIF-8@ZIF-67 was synthesized by the epitaxial growth method and then was utilized as a carrier for encapsulating lipase (PFL) through the co-precipitation method, resulting in the preparation of immobilized lipase (PFL@ZIF-8@ZIF-67). Subsequently, it was further treated with glutaraldehyde to improve protein immobilization yield. Under optimal immobilization conditions, the specific hydrolytic activity of PFL@ZIF-8@ZIF-67 was 20.4 times higher than that of the free PFL. The prepared biocatalyst was characterized and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR). Additionally, the thermal stability of PFL@ZIF-8@ZIF-67 at 50 °C was significantly improved compared to the free PFL. After 7 weeks at room temperature, PFL@ZIF-8@ZIF-67 retained 78% of the transesterification activity, while the free enzyme was only 29%. Finally, PFL@ZIF-8@ZIF-67 was applied to the neryl acetate preparation in a solvent-free system, and the yield of neryl acetate reached 99% after 3 h of reaction. After 10 repetitions, the yields of neryl acetate catalyzed by PFL@ZIF-8@ZIF-67 and the free PFL were 80% and 43%, respectively.
Topics: Enzymes, Immobilized; Pseudomonas fluorescens; Lipase; Esterification; Enzyme Stability; Zeolites; Spectroscopy, Fourier Transform Infrared; Temperature; Acetates; X-Ray Diffraction; Biocatalysis; Imidazoles
PubMed: 38930986
DOI: 10.3390/molecules29122922 -
Journal of Vector Borne Diseases 2022Bacillus subtilis subsp. subtilis (VCRC B471) and Pseudomonas fluorescens (B426) produce mosquitocidal biosurfactant, surfactin and di-rhamnolipid. The objective of the...
BACKGROUND & OBJECTIVES
Bacillus subtilis subsp. subtilis (VCRC B471) and Pseudomonas fluorescens (B426) produce mosquitocidal biosurfactant, surfactin and di-rhamnolipid. The objective of the study was to carry out a small-scale field evaluation of the two biosurfactants to determine the efficacy, application dosage, residual activity and frequency of application against Anopheles stephensi immatures in selected sites in Goa, India.
METHODS
Surfactin (VCRC B471) and di-rhamnolipid (VCRC B426) were formulated as aqueous suspensions (5% AS), and were applied at the dosages of 34, 51 and 68 mL/m and 27, 41 and 54 mL/m respectively. Two experiments were carried out with the two formulations.
RESULTS
Surfactin (VCRC B471) formulation was effective at all the dosages and there was sustained reduction (>80%) in immature density in the treated sites up to 18 days in experiment 1 and up to 15 days in experiment 2. No pupae were found in the treated sites throughout the study. Di-rhamnolipid (VCRC B426) formulation was also found to reduce the immature density in the treated sites up to 14 days in experiment 1 and up to 15 days in experiment 2.
INTERPRETATION & CONCLUSION
For VCRC B471, the optimum application dosage determined was 51 mL/m and for VCRC B426, 27mL/m. The formulations are to be applied fortnightly for effective control of Anopheles. The application dosage determined in the present study can be used for large scale field evaluation to assess their suitability for use in public health programmes for the control of Anopheles mosquitoes vectoring malaria.
Topics: Animals; Humans; Anopheles; Pseudomonas fluorescens; Malaria; Mosquito Vectors; Bacillus subtilis
PubMed: 36511041
DOI: 10.4103/0972-9062.342401