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Frontiers in Microbiology 2020In some conditions, bacteria self-organize into biofilms, supracellular structures made of a self-produced embedding matrix, mainly composed of polysaccharides, DNA,...
In some conditions, bacteria self-organize into biofilms, supracellular structures made of a self-produced embedding matrix, mainly composed of polysaccharides, DNA, proteins, and lipids. It is known that bacteria change their colony/matrix ratio in the presence of external stimuli such as hydrodynamic stress. However, little is still known about the molecular mechanisms driving this self-adaptation. In this work, we monitor structural features of biofilms grown with and without hydrodynamic stress. Our measurements show that the hydrodynamic stress concomitantly increases the cell density population and the matrix production. At short growth timescales, the matrix mediates a weak cell-cell attractive interaction due to the depletion forces originated by the polymer constituents. Using a population dynamics model, we conclude that hydrodynamic stress causes a faster diffusion of nutrients and a higher incorporation of planktonic bacteria to the already formed microcolonies. This results in the formation of more mechanically stable biofilms due to an increase of the number of crosslinks, as shown by computer simulations. The mechanical stability also relies on a change in the chemical compositions of the matrix, which becomes enriched in carbohydrates, known to display adhering properties. Overall, we demonstrate that bacteria are capable of self-adapting to hostile hydrodynamic stress by tailoring the biofilm chemical composition, thus affecting both the mesoscale structure of the matrix and its viscoelastic properties that ultimately regulate the bacteria-polymer interactions.
PubMed: 33510716
DOI: 10.3389/fmicb.2020.588884 -
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 -
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 -
Plants (Basel, Switzerland) Feb 2021to discover the interrelationship between growth, protection and photosynthesis induced by N21.4 in tomato () challenged with the leaf pathogen , and to define its...
AIMS
to discover the interrelationship between growth, protection and photosynthesis induced by N21.4 in tomato () challenged with the leaf pathogen , and to define its priming fingerprint.
METHODS
Photosynthesis was determined by fluorescence; plant protection was evaluated by relative disease incidence, enzyme activities by specific colorimetric assays and gene expression by qPCR. Changes in Reactive Oxygen Species (ROS) scavenging cycle enzymes and pathogenesis related protein activity and expression were determined as metabolic and genetic markers of induction of systemic resistance.
RESULTS
N21.4 significantly protected plants and increased dry weight. Growth increase is supported by significant increases in photochemical quenching together with significant decreases in energy dissipation (Non-Photochemical Quenching, NPQ). Protection was associated with changes in ROS scavenging cycle enzymes, which were significantly increased on N21.4 + pathogen challenged plants, supporting the priming effect. Superoxide Dismutase (SOD) was a good indicator of biotic stress, showing similar levels in pathogen- and N21.4-treated plants. Similarly, the activity of defense-related enzymes, ß-1,3-glucanase and chitinase significantly increased in post-pathogen challenge state; changes in gene expression were not coupled to activity.
CONCLUSIONS
protection does not compromise plant growth; N21.4 priming fingerprint is defined by enhanced photochemical quenching and decreased energy dissipation, enhanced chlorophylls, primed ROS scavenging cycle enzyme activity, and glucanase and chitinase activity.
PubMed: 33572123
DOI: 10.3390/plants10020331 -
Saudi Journal of Biological Sciences Nov 2021Microbial levan has great potential as a functional biopolymer in different fields including foods, feeds, cosmetics, and the pharmaceutical and chemical industries. In...
Microbial levan has great potential as a functional biopolymer in different fields including foods, feeds, cosmetics, and the pharmaceutical and chemical industries. In this study, a good levan producer bacterial strain of strain ES, isolated from soil in Egypt in a previous study, was used. Levan production by this strain was optimized using Plackett-Burman experimental design (PBD) to screen the critical factors of several process variables and Centered Central Composite Design (CCD) was applied for further estimation of the relationship between the variables and the response as well as optimization of the levels. Plackett-Burman (P-B) design showed a p-value 0.0144 less than 0.05 indicated the significance of the model. Sucrose, potassium dihydrogen phosphate, yeast extract and pH value showed the most significant effect on levan concentration at the values of 89.17, 65.83, 24.17, and 15.83, respectively. The purified levan polymer was characterized using different Physico-chemical methods such as Fourier Transform Infrared Spectrometer (FTIR), Nuclear magnetic resonance (NMR), and High-Performance Liquid Chromatography (HPLC) to determine the main composition and functional groups in the obtained polymer. HPLC results indicated that the polymer purification increased the percentage of fructose residue from 75 up to 89. Furthermore, H and C NMR spectroscopy analysis showed great matching between the obtained signal for our polymer with that reported in other peoples work. The obtained levan polymer exhibited cytotoxic activity against Human epidermoid Skin carcinoma and Hepatocellular carcinoma with IC50 of 469 and 222.7 µg/ml, respectively. Antioxidant activity was determined using DPPH assay and the percentage of inhibition at 1000 µg/ml was found to be <50 (13.89 ± 1.07) with IC50 of (24.42 ± 0.87).
PubMed: 34764781
DOI: 10.1016/j.sjbs.2021.08.008 -
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 -
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