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Food Research International (Ottawa,... Nov 2023This study established microbial growth models for fresh-cut cucumber packaged with different O transmission rate (OTR) films. Biaxially oriented polyamide/low-density...
This study established microbial growth models for fresh-cut cucumber packaged with different O transmission rate (OTR) films. Biaxially oriented polyamide/low-density polyethylene (BOPA/LDPE) film (Ⅰ: OTR5, Ⅳ: OTR48) and polyethylene (PE) film (Ⅱ: OTR2058, Ⅲ: OTR3875) were used to construct a passive modified atmosphere packaging (MAP). Mathematic models have been established to account for dynamic variations in the O/CO concentration and their impacts on Pseudomonas fluorescens growth. The coupling models included: 1) respiration models of cucumber and P. fluorescens based on Michaëlis-Menten equation, 2) coupling gas exchange models based on Fick's law that contained models of P. fluorescens growth and respiration, 3) coupling microbial growth models contained respiration and gas exchange models. Coupling model with Baranyi function successfully fitted variations of O/CO concentration and P. fluorescens growth in the two packaging. In addition, quality properties of packed fresh-cut cucumber were determined. The film Ⅳ (OTR48) as a high barrier film showed the highest inhibition of P. fluorescens growth, adequately retained its colour, firmness and total soluble solid (TSS) concentration in contrast to the PE films packaging. The constructed coupling models can be utilized for assessing the shelf life and microbial growth of fresh-cut vegetables with spoilage dominated by pseudomonads.
Topics: Cucumis sativus; Food Packaging; Food Preservation; Pseudomonas fluorescens; Carbon Dioxide; Food Microbiology; Atmosphere
PubMed: 37803617
DOI: 10.1016/j.foodres.2023.113306 -
Physiologia Plantarum 2023Salt stress is an alarming abiotic stress that reduces mustard growth and yield. To attenuate salt toxicity effects, plant growth-promoting rhizobacteria (PGPR) offers a...
Salt stress is an alarming abiotic stress that reduces mustard growth and yield. To attenuate salt toxicity effects, plant growth-promoting rhizobacteria (PGPR) offers a sustainable approach. Among the various PGPR, Pseudomonas fluorescens (P. fluorescens NAIMCC-B-00340) was chosen for its salt tolerance (at 100 mM NaCl) and for exhibiting various growth-promoting activities. Notably, P. fluorescens can produce auxin, which plays a role in melatonin (MT) synthesis. Melatonin is a pleiotropic molecule that acts as an antioxidant to scavenge reactive oxygen species (ROS), resulting in stress reduction. Owing to the individual role of PGPR and MT in salt tolerance, and their casual nexus, their domino effect was investigated in Indian mustard under salt stress. The synergistic action of P. fluorescens and MT under salt stress conditions was found to enhance the activity of antioxidative enzymes and proline content as well as promote the production of secondary metabolites. This led to reduced oxidative stress following effective ROS scavenging, maintained photosynthesis, and improved growth. In mustard plants treated with MT and P. fluorescens under salt stress, eight flavonoids showed significant increase. Kaempferol and cyanidin showed the highest concentrations and are reported to act as antioxidants with protective functions under stress. Thus, we can anticipate that strategies involved in their enhancement could provide a better adaptive solution to salt toxicity in mustard plants. In conclusion, the combination of P. fluorescens and MT affected antioxidant metabolism and flavonoid profile that could be used to mitigate salt-induced stress and bolster plant resilience.
Topics: Antioxidants; Melatonin; Mustard Plant; Pseudomonas fluorescens; Reactive Oxygen Species; Flavonoids
PubMed: 38148187
DOI: 10.1111/ppl.14092 -
Biochemistry Oct 20224-Formylaminooxyvinylglycine (FVG) is an herbicidal and antibacterial nonproteinogenic amino acid produced by several strains of the species complex. It contains a...
4-Formylaminooxyvinylglycine (FVG) is an herbicidal and antibacterial nonproteinogenic amino acid produced by several strains of the species complex. It contains a unique vinyl alkoxyamine moiety with an O-N bond, and its biosynthetic origin remains unknown. Here, we show that the cluster from WH6 is responsible for the biosynthesis of FVG and two additional O-N bond-containing oxyvinylglycines, guanidinooxyvinylglycine and aminooxyvinylglycine. Feeding studies in the producing bacteria indicate that these compounds originate from homoserine. We identify a formyltransferase that is required for the production of FVG and characterize the activity of this enzyme toward amino acids with a side chain amine. Sequence similarity network analysis reveals that GvgI and homologues make up a distinct group from the main classes of formyltransferases.
Topics: Amines; Amino Acids; Anti-Bacterial Agents; Glycine; Homoserine; Hydroxymethyl and Formyl Transferases; Pseudomonas fluorescens
PubMed: 36126313
DOI: 10.1021/acs.biochem.2c00374 -
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 -
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) 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 -
Microorganisms Dec 2023Coal mining has caused significant soil nitrogen loss in mining areas, limiting reclamation and reuse in agriculture. This article studies the effects of organic...
Coal mining has caused significant soil nitrogen loss in mining areas, limiting reclamation and reuse in agriculture. This article studies the effects of organic fertilizer, inorganic fertilizer, and the combined application of with the ability of nitrogen fixation on soil nitrogen accumulation and composition in the reclamation area of the Tunlan Coal Mine from 2016 to 2022 under the conditions of equal nitrogen application, providing a scientific basis for microbial fertilization and the rapid increase in nitrogen content in the reclaimed soil of mining areas. The results showed that as the reclamation time increased, the nitrogen content and the composition and structure of the soil treated with fertilization rapidly evolved toward normal farmland soil. The soil nitrogen content increased most rapidly in the presence of added + organic fertilizer (MB). Compared to other treatments (inorganic fertilizer (CF), organic fertilizer (M), and + inorganic fertilizer (CFB)), MB increased total nitrogen (TN) to normal farmland soil levels 1-3 years earlier. The comprehensive scores of MB and CFB on the two principal components increased by 1.58 and 0.79 compared to those of M and CF treatments, respectively. This indicates that the combination of and organic fertilizer improves soil nitrogen accumulation more effectively than the combination of and inorganic fertilizer. In addition, the application of increases the content of unknown nitrogen (UN) in acid-hydrolysable nitrogen (AHN) and decreases the content of amino acid nitrogen (AAN) and ammonia nitrogen (AN). However, there was no significant effect on the content of ammonium nitrogen (NH-N) and nitrate nitrogen (NO-N) in soil-mineralized nitrogen (SMN). When combined with inorganic fertilizer, the contribution of SMN to TN increased by 14.78%, while when combined with organic fertilizer, the contribution of AHN to TN increased by 44.77%. In summary, the use of is beneficial for nitrogen recovery in the reclaimed soil of coal-mining areas. The optimal fertilization method under the experimental conditions is the combination of and organic fertilizer.
PubMed: 38276177
DOI: 10.3390/microorganisms12010009 -
Journal of Applied Microbiology Oct 2022Hexanal and geraniol are essential oil components with anti-quorum sensing (QS) activity against Pseudomonas fluorescens. This study demonstrated that QS inhibition...
AIM
Hexanal and geraniol are essential oil components with anti-quorum sensing (QS) activity against Pseudomonas fluorescens. This study demonstrated that QS inhibition (QSI) efficacy of the hexanal and geraniol combination (HG) was significantly higher when compared to those of their mono-counterparts at the same concentration.
METHODS AND RESULTS
Tests on P. fluorescens motility, biofilm formation, acyl-homoserine lactones' (AHLs) production, gene expression in vitro, and molecular docking in silico were conducted to evaluate the synergistic effect of hexanal and geraniol on QSI. HG mixture at 0.5 minimal inhibitory concentration (MIC) showed a strong synergistic inhibition of biofilm formation (51.8%), motility (60.13%), and extracellular protease activity (58.9%) of P. fluorescens. The synthesis of AHLs, e.g., C -HSL and C -HSL, was inhibited by hexanal, geraniol, and HG; both AHLs are responsible for regulating virulence factors in P. fluorescens. The expression of pcoI and gacA genes regulating AHL synthetase and sensor kinase was significantly down-regulated by HG (0.29 and 0.38-fold) at 0.5 MIC. Hexanal and HG showed significant inhibition of the expression of pcoR and gacS genes, which are responsible for AHL receptor protein and response regulation; however, geraniol failed to downregulate the two genes. Molecular docking in silico also supported these findings. Hexanal, which gets inserted into the minor groove of pcoI/pcoR DNA fragments, inhibits the expression of both the genes. Both hexanal (-31.487 kcal/mol) and geraniol (-25.716 kcal/mol) had a higher binding affinity with PcoI protein than the halogenated furanone C30 (-24.829 kcal/mol), which is a known competitor of AHLs. Similarly, hexanal and geraniol strongly bind to the PcoR protein also.
CONCLUSIONS
It was found that HG at 0.5 MIC could effectively inhibit QS by suppressing the expression of pcoR/gacS and gacA/gacS genes and therefore, could inhibit the motility and biofilm formation of P. fluorescens.
SIGNIFICANCE AND IMPACT OF THE STUDY
The present study indicated that HG at sub-MIC as QS inhibitor could be further developed as a new preservative of agri-food products.
Topics: Acyclic Monoterpenes; Acyl-Butyrolactones; Aldehydes; Biofilms; Ligases; Molecular Docking Simulation; Oils, Volatile; Peptide Hydrolases; Pseudomonas fluorescens; Virulence Factors
PubMed: 35007388
DOI: 10.1111/jam.15446 -
Pediatric Blood & Cancer Oct 2021Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Bacterial L-asparaginase has played an important role in ALL treatment for several decades;... (Review)
Review
Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Bacterial L-asparaginase has played an important role in ALL treatment for several decades; however, hypersensitivity reactions to Escherichia coli-derived asparaginases often preclude their use. Inability to receive asparaginase due to hypersensitivities is associated with poor patient outcomes. Erwinia chrysanthemi-derived asparaginase (ERW) is an effective, non-cross-reactive treatment option, but is limited in supply. Consequently, alternative asparaginase preparations are needed to ensure asparaginase availability for patients with hypersensitivities. Recombinant technology can potentially address this unmet need by programming cells to produce recombinant asparaginase. JZP-458, a recombinant Erwinia asparaginase derived from a novel Pseudomonas fluorescens expression platform with no immunologic cross-reactivity to E. coli-derived asparaginases, has the same primary amino acid sequence as ERW, with comparable activity based on in vitro measurements. The efficient manufacturing of JZP-458 would provide an additional asparaginase preparation for patients with hypersensitivities.
Topics: Antineoplastic Agents; Asparaginase; Child; Dickeya chrysanthemi; Drug Hypersensitivity; Escherichia coli; Humans; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Pseudomonas fluorescens; Technology
PubMed: 34105243
DOI: 10.1002/pbc.29169 -
Toxicon : Official Journal of the... May 2021Aflatoxins are carcinogenic compounds produced by certain Aspergillus spp and naturally contaminate poultry rations. Exposure to low levels of Aflatoxin B1 (AFB1) in...
Aflatoxins are carcinogenic compounds produced by certain Aspergillus spp and naturally contaminate poultry rations. Exposure to low levels of Aflatoxin B1 (AFB1) in poultry feeds is the second most threatening issue facing the poultry industry in Egypt; it can cause a reduction in growth, egg production, and compromised immune functions, resulting in significant economic loss. Hence, a safe, effective and eco-friendly detoxification method is strongly required. Biological decontamination is a promising approach to reduce aflatoxin levels within threshold limits. This study explores the biodegradation capacity of bacteria isolated from the moldy feed, soil and poultry feces in various poultry farms against AFB1 (100 ppb), G1 (100 ppb), B2 (30 ppb), G2 (30 ppb). Sixty-five bacterial isolates were initially screened using coumarin media with a concentration of (0.01%-0.5%) coumarin. Only one soil isolate (SZ1) grew at the highest concentration (0.5%). Coumarin and Aflatoxin degradation rates of ten promising isolates were measured using spectrophotometry and HPLC. Six isolates reduced AFG1 by more than 90% in the liquid medium, five reduced AFB2 while only four did the same with AFB1& AFG2. Impressively, isolate SZ1 (identified as Pseudomonas fluorescens) exhibited the best degradation capacity to both coumarin and aflatoxin with 100% degradation of AFG1 and 99% degradation of AFB1, AFB2 and AFG2. Biochemical and molecular identification of the ten isolates revealed that they belong to four genera; Bacillus (6), Pseudomonas (2), Enterococcus (1) and Stenotrophomonas (1). Factors affecting Pseudomonas fluorescens SZ1 degradation activity was further investigated. Optimum temperature, time and pH for maximum aflatoxin degradation were at 37 °C, 72 h and 7, respectively. Treatment with proteinase K reduced the degradation activity of G1 (31% ± 1.438), B1 (42% ± 1.438), G2 (19% ± 1.097), and B2 (25% ± 1.732), suggesting that the effective component in aflatoxin degradation may be protein in nature. Our study suggests the biocontrol potential of several different species isolated from poultry farms; B. haynesii, B. licheniformis, B. tequilensis, B. subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, Enterococcus casseliflavus, and Stenotrophomonas maltophilia. The results proposed Pseudomonas fluorescens SZ1 as an excellent candidate for bioremediation and decontamination of aflatoxin in feed matrices. To the best of our knowledge, this is the first report identifying B. haynesii, Enterococcus casseliflavus, B. tequilensis and B. amyloliquefaciens with aflatoxin degradation activity.
Topics: Aflatoxin B1; Aflatoxins; Animals; Biodegradation, Environmental; Egypt; Enterococcus; Farms; Poultry
PubMed: 33610638
DOI: 10.1016/j.toxicon.2021.02.005