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•The combined analysis method of Genome and STRING databases was applied to the prediction of QS regulatory targets.•The method were shown to accurately predict the regulatory targets ...of QS in metabolism, virulence and antibiotic resistance.•Adhesion gene clusters played a key role on H. alvei colonization ability mediated by QS systems.•QS improved antibiotic resistance not only by forming biofilms but also by regulating the efflux of antibiotics.
In this study, we sequenced and characterized the genome of H. alvei to grasp the genetic basis of its physiological activities, including QS, metabolism, virulence and antibiotic resistance, and then mapped these functional gene clusters obtained from KEGG pathways to the STRING database to predict the QS-regulated targets in these pathways. H. alvei was found to possess 63 QS-related genes, most of which were closely related to amino acid metabolism, especially methionine pathway, but were not directly related to carbon and energy metabolism. Furthermore, the adhesion gene clusters were closely relevant to the QS gene clusters as well as to the infection gene clusters, while only one node (KdsD) was predicted between the QS gene clusters and infection gene clusters, suggesting that QS might influence the infection by regulating adhesion. QS might confer cross-resistance to microorganisms not only by regulating the formation of biofilms but also by affecting the efflux of antibiotics. In addition, the interspecies and intraspecies patterns of absence/presence for QS and its target genes were determined to shed light on the conservation of the QS regulatory mechanism among the phylogenetically related species. Taken together, the proposed methodology could expand the spectrum of possible applications of genome-based analysis to decipher the basic metabolic relationship of a microorganism, especially when studying new isolates.
In this study, the antibacterial effects of benzyl isothiocyanate (BITC) against Vibrio parahaemolyticus (V. parahaemolyticus) were investigated at the protein level using label-free quantitative ...proteomic analysis. The results showed that 243 differentially expressed proteins were induced by BITC at 10 μmol/L in V. parahaemolyticus. In particular, outer membrane protein A (OmpA), outer membrane protein U (OmpU) and outer membrane protein W (OmpW) were significantly downregulated by 44.9%–66.3%. By combining scanning electron microscopy observations, and gene ontology enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and STRING analyses, the modes of BITC action against V. parahaemolyticus were speculated to be a reduction in biofilm production, loss of outer membrane integrity and inhibition of transmembrane transport, and inhibition of response to stimulus and metabolic pathways. Furthermore, molecular docking analysis was conducted to investigate the action sites of BITC with OmpA, OmpU and OmpW of V. parahaemolyticus. The results showed that the docking scores of BITC with OmpA, OmpU and OmpW were between −5.36 and −6.05 kcal/mol, confirming the stability of these complexes. Therefore, these results suggest that outer membrane proteins related to the reduction of biofilm production play an important role in the antibacterial activity of BITC against V. parahaemolyticus.
•BITC showed antibacterial effect against Vibrio parahaemolyticus.•Proteomic analysis of the effect of BITC on Vibrio parahaemolyticus.•BITC inhibited biofilm formation of Vibrio parahaemolyticus.•BITC reduced the expression of OmpA, OmpU and OmpW in Vibrio parahaemolyticus.•BITC has high binding affinity to OmpA, OmpU and OmpW.
•A novel photoelectrochemical immunosensor for the detection of VP was assembled.•Ho3+ and Yb3+ doping TiO2 improved the photocurrent responsiveness of PEC sensors.•The working electrode based on ...CdSe QDs sensitized Ho3+/Yb3+-TiO2 was constructed.•PEC sensors had a detection limit of 25 CFU/mL, a detection range of 102–108 CFU/mL.•This study provides a promising rapid and ultrasensitive detection method for VP.
A novel photoelectrochemical (PEC) immunosensor based on CdSe quantum dots (QDs) sensitized Ho3+/Yb3+-TiO2 for the detection of Vibrio parahaemolyticus (VP) was assembled. The working electrode was constructed via the layer-by-layer (LBL) method with the Ho3+/Yb3+-TiO2, CdSe QDs, NHS/EDC, antibody of VP (anti-VP), bovine serum albumin (BSA) modified on the surface of the FTO in sequence. Ascorbic acid (AA) acts as an electron donor to combine photogenerated holes in order to provide a stable current system. Ho3+ and Yb3+ co-doping TiO2 broadened the spectral response range of TiO2 to the infrared region and improved the photocurrent responsiveness of TiO2. The PEC immunosensor, with Ho3+/Yb3+ ratio of 1:5, Ho3+/Yb3+-TiO2 of 2 mg/mL and PBS solution of pH 7.4, had an optimal photocurrent responsiveness. Immobilization of anti-VP was by classical NHS/EDC coupling reactions between COOH groups of CdSe QDs and NH2 groups of the anti-VP. The results indicated that PEC immunosensors had a low detection limit of 25 CFU/mL, a wide detection range of 102–108 CFU/mL, high stability, low price, and short detection time. This method could be promising for the rapid and ultrasensitive detection of pathogenic microorganisms in the food.
In recent years, using external mechanical energy to solve environmental pollution problems has gradually become a promising strategy, such as piezoelectric catalysis and piezoelectric ...photocatalysis. In this paper, a series of HKUST-1/g-C3N4 composite materials were successfully synthesized by the combination of g-C3N4 with S-vacancy and porous HKUST-1 semiconductor. Under visible light irradiation and ultrasonic action, the catalytic activity of HKUST-1/g-C3N4 on RhB degradation was investigated. When the mass ratio of HKUST-1 to g-C3N4 is 1:0.3 during the process of piezoelectric photocatalysis, the as-prepared HKUST-1/g-C3N4 composite had the best RhB degradation performance up to 94.42%, which is about 2.83 times that of visible light and 3.56 times that of ultrasonic waves. According to the result of the trapping experiment, the process of piezo-photocatalytic reaction could produce the number of reactive oxygen species (ROS), and the hydroxyl radical (•OH) was crucial in the breakdown of pollutants.
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•HKUST-1/g-C3N4 with the piezo-photocatalytic property was synthesized.•The catalytic mechanism under ultrasound and UV–visible light was revealed.•Superior piezo-photocatalytic activity has been obtained by HKUST-1/g-C3N4.
To effectively utilize the potent antibacterial capacity of benzyl isothiocyanate (BITC), attempts have been made to apply it in the natural biopolymeric film by solving its high volatility. In this ...study, we encapsulated BITC in the carrier β-cyclodextrin (βCD) to form an inclusion complex to protect BITC from volatilization and then introduced the complex to κ-carrageenan (KC) to fabricate an antibacterial food packaging film. The addition of the BITC-βCD complex enhanced the storage modulus and promoted a denser network structure formation for KC hydrogel by rheological measurements and microstructure observations, respectively. In terms of antibacterial capacity, BITC-βCD-KC film displayed favorable antibacterial potential against both Staphylococcus aureus and Listeria monocytogenes after co-incubation for 18 h, with the inhibition zone diameters of 25.7 mm and 16.7 mm, respectively. As an active packing material, the BITC-βCD-KC film exhibited a sustained inhibition effect against the proliferation of these two bacteria on the chicken meat surface at 25 °C. Moreover, the chicken breasts packaged with BITC-βCD-KC film had a total viable count of 4.7 Log CFU/g, obviously lower than that of the unpackaged sample (9.8 Log CFU/g) after storage at 4 °C for 8 days. These results suggested that the KC film with the BITC-βCD inclusion complex might have promising potential as an antibacterial food packaging material for food preservation.
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•●Benzyl isothiocyanate-β-cyclodextrin (BITC-βCD) promoted κ-carrageenan (KC) gelation.•●BITC-βCD inclusion complex improved hydrophobicity and thermal stability of KC film.•●BITC-βCD-KC film had antibacterial activity against S. aureus and L. monocytogenes.•●BITC-βCD-KC film could suppress the growth of microorganisms in the chicken breast.
In the present study, NaNbO3-CdS nanorods composites with pyroelectric effect were used to degrade RhB solution and sterilize Salmonella under room-temperature cold-hot cycles. The pyrocatalytic ...decomposition rate of NaNbO3-CdS reached 90 % under 45 cold-hot (25–55 °C) cycles while the antibacterial rate of NaNbO3-CdS also achieved 90 % under 45 cold-hot (17–37 °C) cycles. Compared with the pyrocatalytic effect of single NaNbO3, with the hole’s radicals and superoxide radicals as the main active species, the pyrocatalytic effect of the NaNbO3-CdS was significantly enhanced. It is mainly attributed to its surface electrons being captured by CdS, thereby reducing the recombination probability of electron pairs. After four repeated experiments, the high pyrocatalytic activity still maintained, which indicated that the property of NaNbO3-CdS composites was stable. The composite nanocatalyst has potential in the degradation of dye pollution and sterilization by temperature difference.
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•NaNbO3-CdS nanorods composites with pyroelectric effect was successfully synthesized.•Pyroelectric catalytic mechanism under room-temperature cold-hot cycles was revealed.•Superior pyrocatalytic and antibacterial activity have been obtained by NaNbO3-CdS.•Heterojunction effectively reduces recombination of pyroelectric electrons and holes.
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•A series of Tm3+/Yb3+-Bi2WO6 catalysts hydrothermally prepared and characterized.•Tm3+/Yb3+-Bi2WO6 showed excellent optical properties.•Significantly enhanced photocatalytic activity ...is achieved when degrading RhB.•This study provides a great way to obtain stable photocatalyst.
Tm3+ and Yb3+ co-doped Bi2WO6 up-conversion photocatalysts (Tm3+/Yb3+:Bi2WO6) were synthesized via co-precipitation route at different calcination temperatures. Doping Tm3+ and Yb3+ into Bi2WO6 lattice and substituting for the fractional Bi3+ were successfully confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The morphology and optical property of the obtained samples were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS) and up-conversion luminescence spectra (UC-PL). The photocatalytic results revealed that the Tm3+/Yb3+:Bi2WO6 exhibited a much superior photocatalytic activity than the pure Bi2WO6 and commercial Degussa P25 for the degradation of rhodamine B (RhB), and the degradation rate reached 97.6% in 25 min. The effects of Tm3+ and Yb3+ on the photocatalytic activity of Bi2WO6 were studied in detail. The improved photocatalytic activity of Bi2WO6 could be attributed to the efficient energy transfer between Tm3+/Yb3+ and Bi2WO6 via infrared to visible up-conversion and the reduced recombination rate of photogenerated electron-hole pairs through co-doping of Tm3+/Yb3+ on Bi2WO6 nanopaticles.
Hafnia alvei, a specific spoilage microorganism, has a strong capacity to destroy food protein and lead to spoilage. The aim of this study was to evaluate the phase-dependent regulation of lux-type ...genes on the spoilage characteristics of H. alvei H4. The auto-inducer synthase gene luxI and a regulatory gene luxR of the quorum sensing systems in H. alvei H4 were knocked out to construct the mutant phenotypes. On this basis, the research found that the luxI and luxR genes had a strong positive influence on not only flagella-dependent swimming ability and biofilm formation but also the production of putrescine and cadaverine. The luxR gene could downregulate putrescine production. The maximum accumulation of putrescine in wild type, ΔluxI, ΔluxR and ΔluxIR were detected at 24 h, reaching up to 695.23 mg/L, 683.02 mg/L, 776.30 mg/L and 724.12 mg/L, respectively. However, the luxI and luxR genes have a potential positive impact on the production of cadaverine. The maximum concentration of cadaverine produced by wild type, ΔluxI, ΔluxR and ΔluxIR were 252.7 mg/L, 194.5 mg/L, 175.1 mg/L and 154.2 mg/L at 72 h. Moreover, the self-organizing map analysis revealed the phase-dependent effects of two genes on spoilage properties. The luxI gene played a major role in the lag phase, while the luxR gene mainly acted in the exponential and stationary phases. Therefore, the paper provides valuable insights into the spoilage mechanisms of H. alvei H4.
