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Foods (Basel, Switzerland) Jan 2024In the food industry, foodborne spoilage bacteria often live in mixed species and attach to each other, leading to changes in spoilage characteristics. Quorum sensing...
In the food industry, foodborne spoilage bacteria often live in mixed species and attach to each other, leading to changes in spoilage characteristics. Quorum sensing (QS) has been reported to be a regulating mechanism for food spoiling by certain kinds of bacteria. Here, the contents of biofilm, extracellular polysaccharides, and biogenic amines in the coculture system of H4 and ATCC13525 were significantly reduced when the QS element of H4 was deleted, confirming that QS of H4 is involved in the dual-species interactions. Then, transcriptomics was used to explore the regulatory mechanism at the mRNA molecular level. The deletion of the QS element decreased the transcript levels of genes related to chemotaxis, flagellar assembly, and the two-component system pathway of H4 in the coculture system. Furthermore, a total of 732 DEGs of ATCC13525 were regulated in the dual species, which were primarily concerned with biofilm formation, ATP-binding cassette transporters, and amino acid metabolism. Taken together, the absence of the QS element of H4 weakened the mutual cooperation of the two bacteria in the coculture system, making it a good target for managing infection with and .
PubMed: 38275703
DOI: 10.3390/foods13020336 -
Environmental Science & Technology Sep 2023Extracellular vesicles (EVs) are membrane-bounded, nanosized particles, produced and secreted by all biological cell types. EVs are ubiquitous in the environment,...
Extracellular vesicles (EVs) are membrane-bounded, nanosized particles, produced and secreted by all biological cell types. EVs are ubiquitous in the environment, operating in various roles including intercellular communication and plant immune modulation. Despite their ubiquity, the role of EV surface chemistry in determining transport has been minimally investigated. Using the zeta (ζ)-potential as a surrogate for surface charge, this work considers the deposition of EVs from the yeast, , and two bacterial species, and , in well-characterized porous medium under various background conditions shown to influence the transport of other environmental colloidal particles: ionic strength and humic acid concentration. The affinity of EVs for the porous medium (glass beads) appeared to be sensitive to changes in ionic strength, as predicted by colloid stability (Derjaguin, Landau, Verwey, and Overbeek or DLVO) theory, and humic acid concentration, while EVs deviated from DLVO predictions, suggesting that mechanisms other than charge stabilization may control the deposition of . Calculations of attachment efficiency from these deposition studies were used to estimate EV transport using a clean-bed filtration model. Based on these calculations, EVs could be transported through such homogeneous porous media up to 15 m.
Topics: Saccharomyces cerevisiae; Humic Substances; Porosity; Extracellular Vesicles; Bacteria
PubMed: 37606695
DOI: 10.1021/acs.est.3c03700 -
Microbial Cell Factories Jun 2024Syringic acid (SA) is a high-value natural compound with diverse biological activities and wide applications, commonly found in fruits, vegetables, and herbs. SA is...
BACKGROUND
Syringic acid (SA) is a high-value natural compound with diverse biological activities and wide applications, commonly found in fruits, vegetables, and herbs. SA is primarily produced through chemical synthesis, nonetheless, these chemical methods have many drawbacks, such as considerable equipment requirements, harsh reaction conditions, expensive catalysts, and numerous by-products. Therefore, in this study, a novel biotransformation route for SA production was designed and developed by using engineered whole cells.
RESULTS
An O-methyltransferase from Desulfuromonas acetoxidans (DesAOMT), which preferentially catalyzes a methyl transfer reaction on the meta-hydroxyl group of catechol analogues, was identified. The whole cells expressing DesAOMT can transform gallic acid (GA) into SA when S-adenosyl methionine (SAM) is used as a methyl donor. We constructed a multi-enzyme cascade reaction in Escherichia coli, containing an endogenous shikimate kinase (AroL) and a chorismate lyase (UbiC), along with a p-hydroxybenzoate hydroxylase mutant (PobA) from Pseudomonas fluorescens, and DesAOMT; SA was biosynthesized from shikimic acid (SHA) by using whole cells catalysis. The metabolic system of chassis cells also affected the efficiency of SA biosynthesis, blocking the chorismate metabolism pathway improved SA production. When the supply of the cofactor NADPH was optimized, the titer of SA reached 133 μM (26.2 mg/L).
CONCLUSION
Overall, we designed a multi-enzyme cascade in E. coli for SA biosynthesis by using resting or growing whole cells. This work identified an O-methyltransferase (DesAOMT), which can catalyze the methylation of GA to produce SA. The multi-enzyme cascade containing four enzymes expressed in an engineered E. coli for synthesizing of SA from SHA. The metabolic system of the strain and biotransformation conditions influenced catalytic efficiency. This study provides a new green route for SA biosynthesis.
Topics: Gallic Acid; Biocatalysis; Escherichia coli; Metabolic Engineering; Methyltransferases; Shikimic Acid; Pseudomonas fluorescens; Biotransformation
PubMed: 38824548
DOI: 10.1186/s12934-024-02441-x -
Plants (Basel, Switzerland) Oct 2023spp. are important pathogens on cereals, capable of causing considerable yield losses and significantly reducing the quality of harvested grains due to contamination...
spp. are important pathogens on cereals, capable of causing considerable yield losses and significantly reducing the quality of harvested grains due to contamination with mycotoxins. The European Union intends to reduce the use of chemical-synthetic plant protection products (csPPP) by up to 50% by the year 2030. To realize this endeavor without significant economic losses for farmers, it is crucial to have both precise early detection of pathogens and effective alternatives for csPPP. To investigate both the early detection of Fusarium head blight (FHB) and the efficacy of selected biological control agents (BCAs), a pot experiment with spring wheat (cv. 'Servus') was conducted under semi-field conditions. Spikes were sprayed with different BCAs prior to inoculation with a mixture of and conidia. While early detection of FHB was investigated by hyperspectral imaging (HSI), the efficiency of the fungal ( sp. T10, T16, T23 and CRP1104) and bacterial ( HG77 and G308) BCAs was assessed by visual monitoring. Evaluation of the hyperspectral images using linear discriminant analysis (LDA) resulted in a pathogen detection nine days post inoculation (dpi) with the pathogen, and thus four days before the first symptoms could be visually detected. Furthermore, support vector machines (SVM) and a combination of LDA and distance classifier (DC) were also able to detect FHB symptoms earlier than manual rating. Scoring the spikes at 13 and 17 dpi with the pathogen showed no significant differences in the FHB incidence among the treatments. Nevertheless, there is a trend suggesting that all BCAs exhibit a diminishing effect against FHB, with fungal isolates demonstrating greater efficacy compared to bacterial ones.
PubMed: 37895997
DOI: 10.3390/plants12203534 -
BioRxiv : the Preprint Server For... May 2024are exposed to a variety of pathogenic and non-pathogenic bacteria species in their natural environment. Correspondingly, has evolved an ability to discern between...
are exposed to a variety of pathogenic and non-pathogenic bacteria species in their natural environment. Correspondingly, has evolved an ability to discern between nutritive and infectious bacterial food sources. Here we show that can learn to avoid the pathogenic bacteria (PF15), and that this learned avoidance behavior is passed on to progeny for four generations, as we previously demonstrated for (PA14) and , using similar mechanisms, including the involvement of both the TGF-β ligand DAF-7 and retrotransposon-encoded virus-like particles. PF15 small RNAs are both necessary and sufficient to induce this transgenerational avoidance behavior. Unlike PA14 or , PF15 does not use P11, Pv1, or a small RNA with homology for this avoidance; instead, an unrelated PF15 small RNA, Pfs1, that targets the Ephrin receptor gene is necessary and sufficient for learned avoidance, suggesting the evolution of yet another bacterial sRNA/ gene target pair involved in transgenerational inheritance of pathogen avoidance. As VAB-2 Ephrin receptor ligand and MACO-1 knockdown also induce PF15 avoidance, we have begun to understand the genetic pathway involved in small RNA targeted pathogenic avoidance. Moreover, these data show that axon guidance pathway genes (VAB-1 and VAB-2) have previously unknown adult roles in regulating neuronal function. may have evolved multiple bacterial specificity-encoded small RNA-dependent mechanisms to avoid different pathogenic bacteria species, thereby providing progeny with a survival advantage in a dynamic environment.
PubMed: 38826453
DOI: 10.1101/2024.05.23.595334 -
Pharmaceutics May 2024In recent decades, ionic liquids (ILs) have garnered research interest for their noteworthy properties, such as thermal stability, low or no flammability, and negligible...
In recent decades, ionic liquids (ILs) have garnered research interest for their noteworthy properties, such as thermal stability, low or no flammability, and negligible vapour pressure. Moreover, their tunability offers limitless opportunities to design ILs with properties suitable for applications in many industrial fields. This study aims to synthetise two series of methylimidazolium ILs bearing long alkyl chain in their cations (C9, C10, C12, C14, C16, C18, C20) and with tetrafluoroborate (BF) and the 1,3-dimethyl-5-sulfoisophthalate (DMSIP) as counter ions. The ILs were characterised using H-NMR and MALDI-TOF, and their thermal behaviour was investigated through DSC and TGA. Additionally, the antimicrobial, anticancer, and cytotoxic activities of the ILs were analysed. Moreover, the most promising ILs were incorporated at different concentrations (0.5, 1, 5 wt%) into polyvinyl chloride (PVC) by solvent casting to obtain antimicrobial blend films. The thermal properties and stability of the resulting PVC/IL films, along with their hydrophobicity/hydrophilicity, IL surface distribution, and release, were studied using DSC and TGA, contact angle (CA), SEM, and UV-vis spectrometry, respectively. Furthermore, the antimicrobial and cytotoxic properties of blends were analysed. The in vitro results demonstrated that the antimicrobial and antitumor activities of pure ILs against t , , strains, and the breast cancer cell line (MCF7), respectively, were mainly dependent on their structure. These activities were higher in the series containing the BF anion and increased with the increase in the methylimidazolium cation alkyl chain length. However, the elongation of the alkyl chain beyond C16 induced a decrease in antimicrobial activity, indicating a cut-off effect. A similar trend was also observed in terms of in vitro biocompatibility. The loading of both the series of ILs into the PVC matrix did not affect the thermal stability of PVC blend films. However, their T decreased with increased IL concentration and alkyl chain length. Similarly, both the series of PVC/IL films became more hydrophilic with increasing IL concentration and alkyl chain. The loading of ILs at 5% concentration led to considerable IL accumulation on the blend film surfaces (as observed in SEM images) and, subsequently, their higher release. The biocompatibility assessment with healthy human dermal fibroblast (HDF) cells and the investigation of antitumoral properties unveiled promising pharmacological characteristics. These findings provide strong support for the potential utilisation of ILs in biomedical applications, especially in the context of cancer therapy and as antibacterial agents to address the challenge of antibiotic resistance. Furthermore, the unique properties of the PVC/IL films make them versatile materials for advancing healthcare technologies, from drug delivery to tissue engineering and antimicrobial coatings to diagnostic devices.
PubMed: 38794304
DOI: 10.3390/pharmaceutics16050642 -
Foods (Basel, Switzerland) Oct 2023Ultra-high temperature sterilized milk (UHT) is a popular dairy product known for its long shelf life and convenience. However, protein gel aging and fat quality defects...
Ultra-high temperature sterilized milk (UHT) is a popular dairy product known for its long shelf life and convenience. However, protein gel aging and fat quality defects like creaming and flavor deterioration may arise during storage. These problems are primarily caused by thermostable enzymes produced by psychrotrophic bacteria. In this study, four representative psychrotrophic bacteria strains which can produce thermostable enzymes were selected to contaminate UHT milk artificially. After 11, 11, 13, and 17 weeks of storage, the milk samples, which were contaminated with , , and , respectively, demonstrated notable whey separation. The investigation included analyzing the protein and fat content in the upper and bottom layers of the milk, as well as examining the particle size, Zeta potential, and pH in four sample groups, indicating that the stability of UHT milk decreases over time. Moreover, the spoiled milk samples exhibited a bitter taste, with the dominant odor being attributed to ketones and acids. The metabolomics analysis revealed that three key metabolic pathways, namely ABC transporters, butanoate metabolism, and alanine, aspartate, and glutamate metabolism, were found to be involved in the production of thermostable enzymes by psychrotrophic bacteria. These enzymes greatly impact the taste and nutrient content of UHT milk. This finding provides a theoretical basis for further investigation into the mechanism of spoilage.
PubMed: 37893644
DOI: 10.3390/foods12203752 -
Microbiology Resource Announcements Jun 2024We provide the complete genome sequence for a novel bacteriophage named UNO-G1W1. This phage was isolated from a single ice cover sampling. The genome was sequenced on...
We provide the complete genome sequence for a novel bacteriophage named UNO-G1W1. This phage was isolated from a single ice cover sampling. The genome was sequenced on the Nanopore MinION, generated with the direct terminal repeat-phage-pipeline and polished with Illumina short reads. Sequence identity classifies the phage as an .
PubMed: 38847506
DOI: 10.1128/mra.00384-24 -
International Journal of Molecular... Jul 2023Green leaf volatiles (GLVs), including short chain volatile aldehydes, are widely used in the flavor and food industries because of their fresh aroma. To meet the...
Green leaf volatiles (GLVs), including short chain volatile aldehydes, are widely used in the flavor and food industries because of their fresh aroma. To meet the growing demand for natural GLVs with high added value, the use of biocatalytic processes appears as a relevant application. In such processes, vegetable oils are bioconverted into GLVs. First, the triacylglycerols of the oils are hydrolyzed by a lipase. Then, the free polyunsaturated fatty acids are converted by a lipoxygenase. Finally, volatile C6 or C9 aldehydes and 9- or 12-oxoacids are produced with a hydroperoxide lyase. Optimization of each biocatalytic step must be achieved to consider a scale-up. In this study, three oils (sunflower, hempseed, and linseed oils) and three lipases (, , and lipases) have been tested to optimize the first step of the process. The experimental design and response surface methodology (RSM) were used to determine the optimal hydrolysis conditions for each oil. Five factors were considered, i.e., pH, temperature, reaction duration, enzyme load, and oil/aqueous ratio of the reaction mixture. lipase was selected as the most efficient enzyme to achieve conversion of 96 ± 1.7%, 97.2 ± 3.8%, and 91.8 ± 3.2%, respectively, for sunflower, hempseed, and linseed oils under the defined optimized reaction conditions.
Topics: Lipase; Hydrolysis; Plant Oils; Biocatalysis; Linseed Oil; Fatty Acids, Nonesterified; Aldehydes
PubMed: 37569649
DOI: 10.3390/ijms241512274 -
Journal of Hazardous Materials Oct 2023Trace element polluted soils pose risks to human and environmental health. Biochar can decrease trace element bioavailability in soils, but their resulting ability to...
Trace element polluted soils pose risks to human and environmental health. Biochar can decrease trace element bioavailability in soils, but their resulting ability to reduce soil toxicity may vary significantly depending on feedstocks used, pyrolysis conditions, and the target pollutants. Chromated copper arsenate (CCA) polluted sites are common, but only very few types of biochar have been tested for these sites. Hence, we tested fourteen well-characterized biochar materials for their ability to bind Cu and reduce toxicity in a CCA polluted soil in a 56-day experiment. Biochar (1%, wt/wt) increased plant (wheat, Triticum aestivum L.) shoot and root growth by 6-58% and 0-73%, reduced soil toxicity to Arthrobacter globiformis by 7-55%, decreased bioavailable Cu (Pseudomonas fluorescens bioreporter) by 5-65%, and decreased free Cu ion activities by 27-89%. The A. globiformis solid-contact test constituted a sensitive ecotoxicological endpoint and deserves further attention for assessment of soil quality. Oil seed rape straw biochar generally performed better than other tested biochar materials. Biochar performance was positively correlated with its high cation exchange capacity, multiple surface functional groups, and high nitrogen and phosphorus content. Our results pave the way for future selection of feedstocks for creation of modified biochar materials with optimal performance in CCA polluted soil.
Topics: Humans; Copper; Trace Elements; Biological Availability; Soil Pollutants; Charcoal; Soil; Triticum
PubMed: 37478594
DOI: 10.1016/j.jhazmat.2023.132067