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Frontiers in Microbiology 2023CFBP2392 has been recognized as a potential biocontrol agent due to its ability to suppress damping-off and root rot disease. This isolate has antibacterial activity...
CFBP2392 has been recognized as a potential biocontrol agent due to its ability to suppress damping-off and root rot disease. This isolate has antibacterial activity as many other strains from the complex. In this work, the antibacterial and antifungal activity of the strain were explored. Dual culture assays evidenced the antifungal activity of the strain against different phytopathogens: sp., , , and . Purification of an antifungal fraction was performed by preparative HPLC from the chemical extraction of growth media. The fraction showed altered growth and ultrastructure. Transmission electron microscopy revealed the purified compound hypertrophied mitochondria, membranous vesicles, and a higher number of vacuoles in cytoplasm. In addition, co-cultivation of CFBP2392 with resulted in an enlarged and deformed cell wall. To gain genomic insights on this inhibition, the complete genome of CFBP2392 was obtained with Oxford Nanopore technology. Different biosynthetic gene clusters (BGCs) involved in specialized metabolites production including a lokisin-like and a koreenceine-like cluster were identified. In accordance with the putative BGCs identified, sequence phylogeny analysis of the MacB transporter in the lokisin-like cluster further supports the similarity with other transporters from the amphisin family. Our results give insights into the cellular effects of the purified microbial metabolite in ultrastructure and provide a genomic background to further explore the specialized metabolite potential.
PubMed: 38033591
DOI: 10.3389/fmicb.2023.1286926 -
Frontiers in Microbiology 2021Raw milk is susceptible to microbial contamination during transportation and storage. producing heat-resistant enzymes have become the most common and harmful...
Raw milk is susceptible to microbial contamination during transportation and storage. producing heat-resistant enzymes have become the most common and harmful psychrophilic microorganisms in the cold chain logistics of raw milk. To rapidly detect in raw milk, the protease gene X was selected as a detection target to construct a set of primers with strong specificity, and a loop-mediated isothermal amplification (LAMP) assay was established. The detection thresholds of the LAMP assay for pure cultured and pasteurized milk were 2.57 × 10 and 3 × 10 CFU/mL, respectively. It had the advantages over conventional method of low detection threshold, strong specificity, rapid detection, and simple operation. This LAMP assay can be used for online monitoring and on-site detection of in raw milk to guarantee the quality and safety of dairy products.
PubMed: 35069513
DOI: 10.3389/fmicb.2021.810511 -
ELife Nov 2019Microscopic water films allow bacteria to survive the seemingly dry surface of plant leaves.
Microscopic water films allow bacteria to survive the seemingly dry surface of plant leaves.
Topics: Plant Leaves; Pseudomonas fluorescens
PubMed: 31674912
DOI: 10.7554/eLife.52123 -
Italian Journal of Food Safety Mar 2023Biofilms represent an evolutionary form of life, which translates from life in free-living cells to a community lifestyle. In natural habitats, biofilms are a...
Biofilms represent an evolutionary form of life, which translates from life in free-living cells to a community lifestyle. In natural habitats, biofilms are a multispecies complex, where synergies or antagonisms can be established. For example, and are associated with a dual-species biofilm that is widespread in dairy plants. In food plants, multiple strategies are devised to control biofilms, including natural compounds such as essential oils (EOs). In this respect, this study evaluated the effectiveness of (L.) Cav. (TEO) and (CEO) against a dual-species biofilm of and , mimicking dairy process conditions. Based on Minimum Inhibitory Concentrations results, the EOs concentration (10 μL/mL) was chosen for the antibiofilm assay at 12°C on polystyrene (PS), and stainless-steel surfaces for 168 h, using a Ricotta-based model system as culture medium. Biofilm biomass was assessed by crystal violet staining, and the planktonic and sessile cells were quantified in terms of Log CFU/cm. Results showed that CEO displayed the greatest antibiofilm activity, reducing significantly (P<0.05) and sessile cells of about 2.5 and 2.8 Log CFU/cm after 72 h, respectively. However, gained the protection of , evading CEO treatment and showing a minimal sessile cell reduction of 0.7 Log CFU/cm after 72 h. Considering the outcome of this study, CEO might have promising perspectives for applications in dairy facilities.
PubMed: 37064519
DOI: 10.4081/ijfs.2023.11048 -
Frontiers in Microbiology 2022A Gram-negative bacteria () was exposed to different concentrations (0, 20, and 40 mg/L) of dimethyl phthalate (DMP) for 8 h, and then Fourier transform infrared...
A Gram-negative bacteria () was exposed to different concentrations (0, 20, and 40 mg/L) of dimethyl phthalate (DMP) for 8 h, and then Fourier transform infrared spectroscopy (FTIR) analysis, lipopolysaccharide content detection, analysis of fatty acids, calcein release test, proteomics, non-targeted metabolomics, and enzyme activity assays were used to evaluate the toxicological effect of DMP on . The results showed that DMP exposure caused an increase in the unsaturated fatty acid/saturated fatty acid (UFA/SFA) ratio and in the release of lipopolysaccharides (LPSs) from the cell outer membrane (OM) of . Moreover, DMP regulated the abundances of phosphatidyl ethanolamine (PE) and phosphatidyl glycerol (PG) of and induced dye leakage from an artificial membrane. Additionally, excessive reactive oxygen species (ROS), malondialdehyde (MDA), and changes in antioxidant enzymes (i.e., catalase [CAT] and superoxide dismutase [SOD]) activities, as well as the inhibition of Ca-Mg-ATPase and Na/K-ATPase activities in , which were induced by the DMP. In summary, DMP could disrupt the lipid asymmetry of the outer membrane, increase the fluidity of the cell membrane, and destroy the integrity of the cell membrane of through lipid peroxidation, oxidative stress, and ion imbalance.
PubMed: 36071970
DOI: 10.3389/fmicb.2022.949590 -
Saudi Journal of Biological Sciences Apr 2021We find out the antimicrobial potential of partially purified 2,4-diacetylphloroglucinol (DAPG) against and fungal plant pathogens isolated from tomato rhizobacterium...
We find out the antimicrobial potential of partially purified 2,4-diacetylphloroglucinol (DAPG) against and fungal plant pathogens isolated from tomato rhizobacterium VSMKU3054. The present study is mainly focused on the control of wilt disease of tomato by our isolate VSMKU3054 and DAPG. The cell free culture filtrate of VSMKU3054 was significantly arrested the growth of and fungal pathogens such as , , and compared to control. The existence of DAPG from the crude metabolites of VSMKU3054 was confirmed on TLC with Rf value 0.34, which is coincide with that of authentic phloroglucinol. The partially purified DAPG exhibited much higher activity against at 30 µg/ml than the fungal plant pathogens compared to control. The antimicrobial partially purified compound was identified as DAPG by UV, FT-IR and GC-MS analysis. The percentage of live cells of when supplemented with DAPG at 30 µg/ml, significantly controlled the living nature of up to 68% compared to tetracycline and universal control observed under high content screening analysis. The selected isolate VSMKU3054 and DAPG significantly controlled wilt disease of tomato up to 59.5% and 42.12% on 3rd and 7th days compared to positive and negative control by detached leaf assay. Further, in silico analysis revealed that high interaction of DAPG encoding protease with lectin which is associated with . Based on our findings, we confirmed that VSMKU3054 and DAPG could be used a potential bio inoculants for the management of bacterial wilt disease of tomato.
PubMed: 33911932
DOI: 10.1016/j.sjbs.2021.02.073 -
Pakistan Journal of Biological Sciences... Jan 2021<b>Background and Objective:</b> Nanoparticles with a little size to an enormous surface (1-100 nm) have expected clinical, mechanical and agricultural...
<b>Background and Objective:</b> Nanoparticles with a little size to an enormous surface (1-100 nm) have expected clinical, mechanical and agricultural applications. This study aimed to produce nano Zinc Oxide (ZnO) and nano Copper Oxide (CuO) particles by green synthesis. <b>Materials and Methods:</b> Two strains of <i>Pseudomonas fluorescens</i> i.e., PSI and PSII, both cell culture supernatants and cell pellets from the two strains were examined separately in CuSO<sub>4</sub> or ZnSO<sub>4</sub> solutions. The supernatants from both strains produced color changes in both solutions referring to the formation of nano CuO or ZnO particles. The solutions were examined for nano-particle characteristics using UV-spectroscopy, particle size and morphology were tested using a scanning electron microscope and transmission electron microscopy. <b>Results:</b> UV-Vis absorption spectrum of solutions at a wavelength range 200-800 nm exhibits a distinct absorption peak in the region of 238-331 and at 303-366 nm for CuO or ZnO NPs, respectively. Absorption bands and the characteristic Surface Plasmon Resonance (SPR) spectra confirm the existence of CuO and ZnO NPs. SEM analysis micrographs indicated that CuO NPs were formed as spherical particles, while the exact shape of ZnO NPs could be identified as oval aggregates. <b>Conclusion:</b> Changes of color occurred in both solutions of two strains referring to the formation of nano CuO or ZnO particles.
Topics: Chemistry Techniques, Synthetic; Copper; Egypt; Metal Nanoparticles; Nanoparticles; Pseudomonas fluorescens; Zinc
PubMed: 34486303
DOI: 10.3923/pjbs.2021.445.453 -
International Journal of Food... Aug 2022Pseudomonas fluorescens is a well-known biofilm former on food contact surfaces and can cause severe cross-contamination in food processing premises. This study aimed to...
Pseudomonas fluorescens is a well-known biofilm former on food contact surfaces and can cause severe cross-contamination in food processing premises. This study aimed to determine the inactivation effect of low-energy X-ray on P. fluorescens planktonic cells in phosphate-buffered saline solution (PBS) and P. fluorescens biofilm cells on food-contact-surface (stainless steel). The results demonstrated that low-energy X-ray irradiation at 125 Gy inactivated 4.60 log CFU/mL and 4.21 log CFU/cm for P. fluorescens planktonic and biofilm cells, respectively. Based on Weibull model, low-energy X-ray achieved t values of 14.8 Gy and 11.6 Gy for P. fluorescens planktonic and biofilm cells, respectively. Apart from cell inactivation, the irradiation also led to the destruction of extracellular polymeric substances (EPS) structure. Low-energy X-ray irradiation markedly damaged bacterial glucose uptake system and resulted in part loss of bacterial membrane potential and integrity. These results suggested the potential of the low-energy X-ray for inactivating P. fluorescens biofilm cells and removing EPS in food industry.
Topics: Anti-Bacterial Agents; Biofilms; Plankton; Pseudomonas fluorescens; Stainless Steel; X-Rays
PubMed: 35605455
DOI: 10.1016/j.ijfoodmicro.2022.109716 -
Journal of Bacteriology Oct 2022Cells in microbial communities on surfaces live and divide in close proximity, which greatly enhances the potential for social interactions. Spatiogenetic structures are...
Cells in microbial communities on surfaces live and divide in close proximity, which greatly enhances the potential for social interactions. Spatiogenetic structures are manifested through competitive and cooperative interactions among the same and different genotypes within a shared space, and extracellular secretions appear to function dynamically at the forefront. A previous experimental evolution study utilizing Pseudomonas fluorescens Pf0-1 colonies demonstrated that diverse mutations in the gene were repeatedly and exclusively selected through the formation of a dominant spatial structure. RsmE's primary molecular function is translation repression, and its homologs regulate various social and virulence phenotypes. Pseudomonas spp. possess multiple paralogs of Rsm proteins, and RsmA, RsmE, and RsmI are the most prevalent. Here, we demonstrate that the production of a mucoid polymer and a biosurfactant are exclusively regulated through RsmE, contradicting the generalized notion of functional redundancy among the Rsm paralogs. Furthermore, we identified the biosurfactant as the cyclic lipopeptide gacamide A. Competition and microscopy analyses showed that the mucoid polymer is solely responsible for creating a space of low cellular density, which is shared exclusively by the same genotype. Gacamide A and other RsmE-regulated products appear to establish a physical boundary that prevents the encroachment of the competing genotype into the newly created space. Although cyclic lipopeptides and other biosurfactants are best known for their antimicrobial properties and reducing surface tension to promote the spreading of cells on various surfaces, they also appear to help define spatial structure formation within a dense community. In densely populated colonies of the bacterium Pseudomonas fluorescens Pf0-1, diverse mutations in the gene are naturally selected by solving the problem of overcrowding. Here, we show that RsmE-regulated secretions function together to create and protect space of low cell density. A biosurfactant generally promotes the spreading of bacterial cells on abiotic surfaces; however, it appears to function atypically within a crowded population by physically defining genotypic boundaries. Another significant finding is that these secretions are not regulated by RsmE's paralogs that share high sequence similarity. The experimental pipeline described in this study is highly tractable and should facilitate future studies to explore additional RsmE-regulated products and address why RsmE is functionally unique from its paralogs.
Topics: Pseudomonas fluorescens; Gene Expression Regulation, Bacterial; Bacterial Proteins; Pseudomonas; Peptides, Cyclic; Lipopeptides; Polymers
PubMed: 36165622
DOI: 10.1128/jb.00285-22 -
Journal of Food Protection Aug 2021Pseudomonas fluorescens is a specific spoilage microorganism of refrigerated marine fish, and is highly adapted to low temperature. Cold shock proteins (CSPs) play an...
ABSTRACT
Pseudomonas fluorescens is a specific spoilage microorganism of refrigerated marine fish, and is highly adapted to low temperature. Cold shock proteins (CSPs) play an important role in cold adaptation of bacteria. In this study, CSP genes were identified from the genome of P. fluorescens PF08 by search of the conserved domain of CSPs with HMMER software, and the CSP physicochemical properties, structures, and functions were analyzed through bioinformatics. Five typical CSPs were identified in the P. fluorescens PF08 genome (PfCSPs). All five PfCSPs are small hydrophilic acidic proteins with a molecular mass of ca. 7.4 kDa. They are located in the cytoplasm and are nonsecretory and nontransmembrane proteins. Multiple sequence alignment analysis indicated that the CSPs are highly conserved between species, especially in DNA-binding sites and RNA-binding motifs that can bind to single-stranded DNA and RNA. The five PfCSPs clustered with CspD from Escherichia coli and Salmonella Typhimurium, which suggests a close homology and high functional similarity among the five PfCSPs and CspD. The secondary and tertiary structures of the PfCSPs are in accordance with the characteristics of the CSP family, and ligand binding sites with higher likelihood were found in PfCSPs. The five PfCSPs were predicted to interact with some of the same proteins that are involved in virulence, stress responses (including to low temperature), cell growth, ribosome assembly, and RNA degradation. The results provide further elucidation of the function of CSPs in adaptation to low temperatures by P. fluorescens.
Topics: Amino Acid Sequence; Animals; Bacterial Proteins; Cold Shock Proteins and Peptides; Cold Temperature; Computer Simulation; Heat-Shock Proteins; Pseudomonas fluorescens
PubMed: 33852731
DOI: 10.4315/JFP-21-044