Quorum sensing(QS)is a regulatory system that regulates the behavior of microbial populations by sensing the concentration of signal molecules that are spontaneously produced and released by bacteria.The strategy of b...Quorum sensing(QS)is a regulatory system that regulates the behavior of microbial populations by sensing the concentration of signal molecules that are spontaneously produced and released by bacteria.The strategy of blocking the QS system and inhibiting the production of virulence factors is termed as quorum quenching(QQ).This strategy attenuates virulence without killing the pathogens,thereby weakening the selective pressure on pathogens and postponing the evolution of QQ-mediated drug resistance.In recent years,there have been significant theoretical and practical developments in the field of QS and QQ.In particular,with the development and utilization of marine resources,more and more marine microbial species have been found to be regulated by these two mechanisms,further promoting the research progress of QS and QQ.In this review,we described the diversity of QS signals and QS-related regulatory systems,and then introduced mechanisms related to QS interference,with particular emphasis on the description of natural QQ enzymes and chemicals acting as QS inhibitors.Finally,the exploitation of quorum sensing quenchers and the practical application of QQ were introduced,while some QQ strategies were proposed as promising tools in different fields such as medicine,aquaculture,agriculture and biological pollution prevention areas.展开更多
The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows ...The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows that tempering sorbite which has excellent overall performance was obtained in both modes. The microstructure of Quenching and Tempering mode welded joints got more fine grain. Even though the hardness of tempering bead welded joints is higher than the general one,it still meets the standards which is lower than 350 HV. The impact absorbing energy of each district of tempering bead welded joints HAZ reached 170 J,which is equal to general one.展开更多
The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and1 m ...The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and1 m M silver nitrate. 100 m M glucose was found to quicken the rate of reaction of silver nanoparticles synthesis.UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer(NTA),Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope(40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.展开更多
Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is trig- gered via auto inducers which passively diffuse across the bacterial envelope and therefore intracell...Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is trig- gered via auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation. N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing indus- tries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance between the pathogenic bacteria＇s virulence factor expression and their auto inducers, quorum quenching is a new effective anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this mainly include the following： （1） the inhibition of signal molecule biosynthesis, （2） blocking signal transduction, and （3） chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination, purification and identification of auto inducers in this paper.展开更多
Background Salmonella Typhimurium challenge causes a huge detriment to chicken production.N-acyl homoserine lactonase(AHLase),a quorum quenching enzyme,potentially inhibits the growth and virulence of Gram-negative ba...Background Salmonella Typhimurium challenge causes a huge detriment to chicken production.N-acyl homoserine lactonase(AHLase),a quorum quenching enzyme,potentially inhibits the growth and virulence of Gram-negative bacteria.However,it is unknown whether AHLase can protect chickens against S.Typhimurium challenge.This study aimed to evaluate the effects of AHLase on growth performance and intestinal health in broilers challenged by S.Typhimurium.A total of 240 one-day-old female crossbred broilers(817C)were randomly divided into 5 groups(6 replicates/group):negative control(NC),positive control(PC),and PC group supplemented with 5,10 or 20 U/g AHLase.All birds except those in NC were challenged with S.Typhimurium from 7 to 9 days of age.All parameters related to growth and intestinal health were determined on d 10 and 14.Results The reductions(P<0.05)in body weight(BW)and average daily gain(ADG)in challenged birds were alleviated by AHLase addition especially at 10 U/g.Thus,samples from NC,PC and PC plus 10 U/g AHLase group were selected for further analysis.S.Typhimurium challenge impaired(P<0.05)intestinal morphology,elevated(P<0.05)ileal inflammatory cytokines(IL-1βand IL-8)expression,and increased(P<0.05)serum diamine oxidase(DAO)activity on d 10.However,AHLase addition normalized these changes.Gut microbiota analysis on d 10 showed that AHLase reversed the reductions(P<0.05)in several beneficial bacteria(e.g.Bacilli,Bacillales and Lactobacillales),along with increases(P<0.05)in certain harmful bacteria(e.g.Proteobacteria,Gammaproteobacteria,Enterobacteriaceae and Escherichia/Shigel a)in PC group.Furthermore,AHLase-induced increased beneficial bacteria and decreased harmful bacteria were basically negatively correlated(P<0.05)with the reductions of ileal IL-1βand IL-8 expression and serum DAO activity,but positively correlated(P<0.05)with the increased BW and ADG.Functional prediction revealed that AHLase abolished S.Typhimurium-induced upregulations(P<0.05)of certain pathogenicity-related pathways such as lipopolysaccharide biosynthesis,shigellosis,bacterial invasion of epithelial cells and pathogenic Escherichia coli infection of gut microbiota.Conclusions Supplemental AHLase attenuated S.Typhimurium-induced growth retardation and intestinal disruption in broilers,which could be associated with the observed recovery of gut microbiota dysbiosis.展开更多
Add the masking agent and biscyclohexanoneoxalyldihydraone into the diluted clarificd liquid of the landfill leachate which was treatmented by digestion and centrifugal filtration to complexate all heavy metal ion in ...Add the masking agent and biscyclohexanoneoxalyldihydraone into the diluted clarificd liquid of the landfill leachate which was treatmented by digestion and centrifugal filtration to complexate all heavy metal ion in the trcatmented liquid, and extracted using CHCl3 many time, then it were demasking and decomposing respectively, and adjusted different pH and formed Me^n＋-PAN coordination compound when these metal ion reaction with PAN. The Fluoresence quenching of Rh6G （λex/λem=543mn/558nm） when the metal ion coordination compound was add into the Rh6G solution step by step, the quenching intensity was directly proportional to the concentration of the metal ion in the certain range. So a new method of fast and simple for determination of trace metal ion in landfill lcachate was established to determine metal ion in sample of different landfill leachate in Three Gorge Water Reservoir, and comparison the classic assay method with satisfactory results.展开更多
Interference with quorum sensing(QS)represents an antivirulence strategy with a significant promise for the treatment of bacterial infections and a new approach to restoring antibiotic tolerance.Over the past two deca...Interference with quorum sensing(QS)represents an antivirulence strategy with a significant promise for the treatment of bacterial infections and a new approach to restoring antibiotic tolerance.Over the past two decades,a novel series of studies have reported that quorum quenching approaches and the discovery of quorum sensing inhibitors(QSIs)have a strong impact on the discovery of anti-infective drugs against various types of bacteria.The discovery of QSI was demonstrated to be an appropriate strategy to expand the anti-infective therapeutic approaches to complement classical antibiotics and antimicrobial agents.For the discovery of QSIs,diverse approaches exist and develop in-step with the scale of screening as well as specific QS systems.This review highlights the latest findings in strategies and methodologies for QSI screening,involving activity-based screening with bioassays,chemical methods to seek bacterial QS pathways for QSI discovery,virtual screening for QSI screening,and other potential tools for interpreting QS signaling,which are innovative routes for future efforts to discover additional QSIs to combat bacterial infections.展开更多
基金supported by the Young Elite Scientists Sponsorship Program by China Association for Science and Technology (CAST) (No. YESS20160009)the National Natural Science Foundation of China (Nos. 31870023, 31571970 and 41506160)
文摘Quorum sensing(QS)is a regulatory system that regulates the behavior of microbial populations by sensing the concentration of signal molecules that are spontaneously produced and released by bacteria.The strategy of blocking the QS system and inhibiting the production of virulence factors is termed as quorum quenching(QQ).This strategy attenuates virulence without killing the pathogens,thereby weakening the selective pressure on pathogens and postponing the evolution of QQ-mediated drug resistance.In recent years,there have been significant theoretical and practical developments in the field of QS and QQ.In particular,with the development and utilization of marine resources,more and more marine microbial species have been found to be regulated by these two mechanisms,further promoting the research progress of QS and QQ.In this review,we described the diversity of QS signals and QS-related regulatory systems,and then introduced mechanisms related to QS interference,with particular emphasis on the description of natural QQ enzymes and chemicals acting as QS inhibitors.Finally,the exploitation of quorum sensing quenchers and the practical application of QQ were introduced,while some QQ strategies were proposed as promising tools in different fields such as medicine,aquaculture,agriculture and biological pollution prevention areas.
基金supported by the Key State Science and Technology Projects(Grant No.2011ZX04016-061 and No.2012ZX06004-001-001-005)
文摘The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows that tempering sorbite which has excellent overall performance was obtained in both modes. The microstructure of Quenching and Tempering mode welded joints got more fine grain. Even though the hardness of tempering bead welded joints is higher than the general one,it still meets the standards which is lower than 350 HV. The impact absorbing energy of each district of tempering bead welded joints HAZ reached 170 J,which is equal to general one.
基金Pravara Institute of Medical Sciences, Loni (MS), India for the financial support
文摘The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and1 m M silver nitrate. 100 m M glucose was found to quicken the rate of reaction of silver nanoparticles synthesis.UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer(NTA),Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope(40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.
文摘Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is trig- gered via auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation. N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing indus- tries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance between the pathogenic bacteria＇s virulence factor expression and their auto inducers, quorum quenching is a new effective anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this mainly include the following： （1） the inhibition of signal molecule biosynthesis, （2） blocking signal transduction, and （3） chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination, purification and identification of auto inducers in this paper.
基金financially supported by the National Natural Science Foundation of China(No.31872390)the Modern Feed Industry Innovation Team Project of Guangdong Province(No.2021KJ115)。
文摘Background Salmonella Typhimurium challenge causes a huge detriment to chicken production.N-acyl homoserine lactonase(AHLase),a quorum quenching enzyme,potentially inhibits the growth and virulence of Gram-negative bacteria.However,it is unknown whether AHLase can protect chickens against S.Typhimurium challenge.This study aimed to evaluate the effects of AHLase on growth performance and intestinal health in broilers challenged by S.Typhimurium.A total of 240 one-day-old female crossbred broilers(817C)were randomly divided into 5 groups(6 replicates/group):negative control(NC),positive control(PC),and PC group supplemented with 5,10 or 20 U/g AHLase.All birds except those in NC were challenged with S.Typhimurium from 7 to 9 days of age.All parameters related to growth and intestinal health were determined on d 10 and 14.Results The reductions(P<0.05)in body weight(BW)and average daily gain(ADG)in challenged birds were alleviated by AHLase addition especially at 10 U/g.Thus,samples from NC,PC and PC plus 10 U/g AHLase group were selected for further analysis.S.Typhimurium challenge impaired(P<0.05)intestinal morphology,elevated(P<0.05)ileal inflammatory cytokines(IL-1βand IL-8)expression,and increased(P<0.05)serum diamine oxidase(DAO)activity on d 10.However,AHLase addition normalized these changes.Gut microbiota analysis on d 10 showed that AHLase reversed the reductions(P<0.05)in several beneficial bacteria(e.g.Bacilli,Bacillales and Lactobacillales),along with increases(P<0.05)in certain harmful bacteria(e.g.Proteobacteria,Gammaproteobacteria,Enterobacteriaceae and Escherichia/Shigel a)in PC group.Furthermore,AHLase-induced increased beneficial bacteria and decreased harmful bacteria were basically negatively correlated(P<0.05)with the reductions of ileal IL-1βand IL-8 expression and serum DAO activity,but positively correlated(P<0.05)with the increased BW and ADG.Functional prediction revealed that AHLase abolished S.Typhimurium-induced upregulations(P<0.05)of certain pathogenicity-related pathways such as lipopolysaccharide biosynthesis,shigellosis,bacterial invasion of epithelial cells and pathogenic Escherichia coli infection of gut microbiota.Conclusions Supplemental AHLase attenuated S.Typhimurium-induced growth retardation and intestinal disruption in broilers,which could be associated with the observed recovery of gut microbiota dysbiosis.
文摘Add the masking agent and biscyclohexanoneoxalyldihydraone into the diluted clarificd liquid of the landfill leachate which was treatmented by digestion and centrifugal filtration to complexate all heavy metal ion in the trcatmented liquid, and extracted using CHCl3 many time, then it were demasking and decomposing respectively, and adjusted different pH and formed Me^n＋-PAN coordination compound when these metal ion reaction with PAN. The Fluoresence quenching of Rh6G （λex/λem=543mn/558nm） when the metal ion coordination compound was add into the Rh6G solution step by step, the quenching intensity was directly proportional to the concentration of the metal ion in the certain range. So a new method of fast and simple for determination of trace metal ion in landfill lcachate was established to determine metal ion in sample of different landfill leachate in Three Gorge Water Reservoir, and comparison the classic assay method with satisfactory results.
基金funded by the National Natural Science Foundation of China (Grant No.: 81803812)
文摘Interference with quorum sensing(QS)represents an antivirulence strategy with a significant promise for the treatment of bacterial infections and a new approach to restoring antibiotic tolerance.Over the past two decades,a novel series of studies have reported that quorum quenching approaches and the discovery of quorum sensing inhibitors(QSIs)have a strong impact on the discovery of anti-infective drugs against various types of bacteria.The discovery of QSI was demonstrated to be an appropriate strategy to expand the anti-infective therapeutic approaches to complement classical antibiotics and antimicrobial agents.For the discovery of QSIs,diverse approaches exist and develop in-step with the scale of screening as well as specific QS systems.This review highlights the latest findings in strategies and methodologies for QSI screening,involving activity-based screening with bioassays,chemical methods to seek bacterial QS pathways for QSI discovery,virtual screening for QSI screening,and other potential tools for interpreting QS signaling,which are innovative routes for future efforts to discover additional QSIs to combat bacterial infections.
