Quorum system is a preferable model to construct distributed access control architecture, but not all quorum system can satisfy the requirements of distributed access control architecture. Aiming at the dependable pro...Quorum system is a preferable model to construct distributed access control architecture, but not all quorum system can satisfy the requirements of distributed access control architecture. Aiming at the dependable problem of authorization server in distributed system and combining the requirements of access control, a set of criterions to select and evaluate quorum system is presented. The scheme and algorithm of constructing an authorization server system based on Paths quorum system are designed, and the integrated sys- tem performance under some servers attacked is fully analyzed. Role-based access control on the Web implemented by this scheme is introduced. Analysis shows that with certain node failure probability, the scheme not only has high dependability but also can satisfy the special requirements of distributed access control such as real-time, parallelism, and consistency of security policy.展开更多
Quorum systems have been used to solve the problem of data consistency in distributed fault-tolerance systems. But when intrusions occur, traditional quorum systems have some disadvantages. For example, synchronous qu...Quorum systems have been used to solve the problem of data consistency in distributed fault-tolerance systems. But when intrusions occur, traditional quorum systems have some disadvantages. For example, synchronous quorum systems are subject to DOS attacks, while asynchronous quorum systems need a larger system size （at least 3f＋1 for generic data, and f fewer for self-verifying data）. In order to solve the problems above, an intrusion-tolerance quorum system （ITQS） of hybrid time model based on trust timely computing base is presented （TTCB）. The TTCB is a trust secure real-time component inside the server with a well defined interface and separated from the operation system. It is in the synchronous communication environment while the application layer in the server deals with read-write requests and executes update-copy protocols asynchronously. The architectural hybridization of synchrony and asynchrony can achieve the data consistency and availability correctly. We also build two kinds of ITQSes based on TTCB, i.e., the symmetrical and the asymmetrical TTCB quorum systems. In the performance evaluations, we show that TTCB quorum systems are of smaller size, lower load and higher availability.展开更多
Rapid developments in network systems of business service have resulted in more reliance on distributed computing, typified by “subscriber/push” architectures. Unfortunately, frequent and unexpectable network failur...Rapid developments in network systems of business service have resulted in more reliance on distributed computing, typified by “subscriber/push” architectures. Unfortunately, frequent and unexpectable network failures were routine, and downtime was not in hours, but in days. High availability has become the most important factor decreasing business risk and improving Quality of Service. Cluster technology has solved the non-stop problem on Local Area Network. However, most technologies including cluster today fail to ensure the non-stop Internet service based on Routers. With good performance on high availability and fault tolerance, quorum systems are very suitable for application to distributed business service networks. In this work, we modeled and developed a non-stop Internet service system based on a new quorum system, circle quorum system, for Boston Mutual Fund Broker, US. With five protocols, it provided highly available data services for clients on Internet.展开更多
The communication system known as quorum sensing (QS) in gram-negative bacteria regulates biofilm formation and many other functions. The particularity of Pseudoalteromonas ulvae TC14 seems to be the absence of a LuxI...The communication system known as quorum sensing (QS) in gram-negative bacteria regulates biofilm formation and many other functions. The particularity of Pseudoalteromonas ulvae TC14 seems to be the absence of a LuxI inducer, and therefore the lack of production of small molecules of Acyl homoserine lactone (AHL). Previous studies had shown that it does not harbor the inducer of the regulatory molecule (AHL). Nevertheless, it is able to regulate these same functions (biofilm, violacein) via AHLs. This could mean the presence of specific receptors for these induction molecules, belonging to the LuxR family. The aim of this study was to test these hypotheses using molecular analysis. Genome sequencing of the P. ulvae TC14 strain was carried out by Molecular Research LP (MR DNA), using the Illumina Hiseq 2500 method. The results revealed the presence of 2,293,242 base pairs, i.e. 100% of the genomic volume. The number of coding gene sequences was 1983, and the Guanine + Cytosine (G+C) percentage of the base number was 41.55%, revealing stability in the sequenced genome. In order to verify the identity of the sequenced genome, a phylogenetic analysis based on RNA16S was carried out. This analysis resulted in 93% homology with the previously sequenced and characterized species Pseudoalteromonas tunicata, showing that it belongs to the genus Pseudoalteromonas. To these comparative results should be added those derived from genome analysis based on nucleotide percentage using the tools available at https://img.jgi.doe.gov/. The results showed that Pseudoalteromonas tunicata D2 has the highest percentage nucleotide identity (ANI) (75.7913%), followed by Pseudoalteromonas flavipulchra NCIMB2033 (72.2736%) and Pseudoalteromonas phenolica KCTC 12086 (71.6685%). Next, the search for the various genes involved in QS was carried out using sequence comparisons via the BLAST method. For LuxI, sequence templates from the genomes of Vibrio, Chromobacterium, Shewanella or even other Pseudoalteromonas species were screened against the TC14 genome. This yielded no conclusive results synonymous with the non-presence of LuxI in TC14 as assumed by previous research. The search for LuxR, on the other hand, gave rise to the presence of eight presumptive sequences. Molecular characterization of the presumptive LuxR sequences was carried out to assess their gene expression. This characterization showed expression of these LuxR homologous sequences in a range from o.11 to 5.33 picograms (pg). Even if these sequences were not analyzed in depth, the retro-transcription technique nevertheless showed a minimum of activity, which could enable us to distinguish them from inactive sequences. The next step was to compare the LuxRs found in TC14 with the so-called Solo LuxRs, which act autonomously. This study shows that P. ulvae TC14 is a bacterium with a particular LuxR-based communication system.展开更多
We assessed the quorum sensing(QS)inhibitory impact of sesamol against the foodborne bacterium Pseudomonas aeruginosa.At concentrations ranging from 50 to 200μg/mL,sesamol significantly inhibited the production of vi...We assessed the quorum sensing(QS)inhibitory impact of sesamol against the foodborne bacterium Pseudomonas aeruginosa.At concentrations ranging from 50 to 200μg/mL,sesamol significantly inhibited the production of virulence factors such as protease,elastase,pyocyanin,rhamnolipid,and chemotaxis,and improved the susceptibility of bacterial and biofilm cells to colistin.Integrated transcriptomics,metabolomics,and docking analyses indicated that exposure to sesamol destroyed the QS system and down-regulated the expressions of genes encoding virulence and antioxidant enzymes.The down-regulation of genes encoding antioxidant enzymes intensified oxidative stress,as demonstrated by the enhancement of reactive oxygen species and H_(2)O_(2).The enhanced oxidative stress changed the components of the cell membrane,improved its permeability,and ultimately enhanced the susceptibility of bacterial and biofilm cells to colistin.Moreover,exposure to sesamol also led to the disorder of amino acid metabolism and energy metabolism,eventually attenuating the pathogenicity of P.aeruginosa.These findings indicated that sesamol can function as a potent anti-virulence agent to defend against food spoilage caused by P.aeruginosa.展开更多
Background:Over the past 50 years,the incidence of obesity has gradually increased,necessitating investigation into the multifactorial contributors to this disease,including the gut microbiota.Bacteria within the huma...Background:Over the past 50 years,the incidence of obesity has gradually increased,necessitating investigation into the multifactorial contributors to this disease,including the gut microbiota.Bacteria within the human gut microbiome communicate using a density-dependent process known as quorum sensing(QS),in which autoinducer(AI)molecules(e.g.,N-acyl-homoserine lactones[AHLs])are produced to enable bacterial interactions and regulate gene expression.Methods:We aimed to disrupt QS using quorum quenching(QQ)lactonases GcL and SsoPox,which cleave AHL signaling molecules in a taxa-specific manner based on differing enzyme affinities for different substrates.We hypothesized that QQ hinders signals from obesity-associated pathobionts,thereby slowing or preventing obesity.Results:In a murine model of dietinduced obesity,we observed GcL and SsoPox treatments have separate sex-dependent and dose-dependent effects on intestinal community composition and diversity.Notably,male mice given 2 mg/mL SsoPox exhibited significant changes in the relative abundances of gram-negative taxa,including Porphyromonadaceae,Akkermansiaceae,Muribaculaceae,and Bacteroidales(Kruskal-Wallis p<0.001).Additionally,we used covariance matrix network analysis to model bacterial taxa co-occurrence due to QQ enzyme administration.There were more associations among taxa in control mice,particularly among gram-negative bacteria,whereas mice receiving SsoPox had the fewest associations.Conclusions:Overall,our study establishes proof of concept that QQ is a targetable strategy for microbial control in vivo.Further characterization and dosage optimization of QQ enzymes are necessary to harness their therapeutic capability for the treatment of chronic microbial-associated diseases.展开更多
Quorum sensing(QS)represents a mechanism through which bacteria engage in communication via chemical signals,a phenomenon prevalent across diverse bacterial species.Recent investigations have elucidated that QS signal...Quorum sensing(QS)represents a mechanism through which bacteria engage in communication via chemical signals,a phenomenon prevalent across diverse bacterial species.Recent investigations have elucidated that QS signaling pathways are pivotal in governing bacterial physiological processes,collective behaviors,and the emergence of drug resistance.Escherichia coli(E.coli),a prominent pathogenic bacterium,is increasingly exhibiting severe drug resistance issues,posing substantial hurdles for clinical interventions.Presently,a burgeoning body of research is exploring the connection between QS signaling pathways and the drug resistance mechanisms in E.coli,unveiling the coordinating function of QS within bacterial communities and its influence on antibiotic resistance.Despite some research advancements,the precise mechanisms underlying the QS signaling pathway remain ambiguous,and its potential applications are somewhat constrained.This article endeavors to systematically review the research progress concerning the QS signaling pathway in the context of clinical drug resistance mechanisms in E.coli,delving into its potential clinical applications and future research avenues,with the aim of offering novel insights and strategies to counteract drug resistance.展开更多
The inhibitory effects of zinc oxide nanoparticles(ZnO NPs)and impacts of N-acylhomoserine lactone(AHL)-based quorum sensing(QS)on biological nitrogen removal(BNR)performance have beenwell-investigated.However,the eff...The inhibitory effects of zinc oxide nanoparticles(ZnO NPs)and impacts of N-acylhomoserine lactone(AHL)-based quorum sensing(QS)on biological nitrogen removal(BNR)performance have beenwell-investigated.However,the effects of ammonia nitrogen(NH_(4)^(+)-N)concentrations on NP toxicity and AHL regulation have seldom been addressed yet.This study consulted on the impacts of ZnO NPs on BNR systems when high NH_(4)^(+)-N concentrationwas available.The synergistic toxic effects of high-strength NH_(4)^(+)-N(200 mg/L)and ZnO NPs resulted in decreased ammonia oxidation rates and dropped the nitrogen removal efficiencies by 17.5%±0.2%.The increased extracellular polymeric substances(EPS)production was observed in response to the high NH_(4)^(+)-N and ZnO NP stress,which indicated the defensemechanism against the toxic effects in the BNR systemswas stimulated.Furthermore,the regulatory effects of exogenous N-decanoyl-homoserine lactone(C_(10)-HSL)-mediated QS system on NP-stressed BNR systems were revealed to improve the BNR performance under different NH_(4)^(+)-N concentrations.The C_(10)-HSL regulated the intracellular reactive oxygen species levels,denitrification functional enzyme activities,and antioxidant enzyme activities,respectively.This probably synergistically enhanced the defense mechanism against NP toxicity.However,compared to the low NH_(4)^(+)-N concentration of 60 mg/L,the efficacy of C_(10)-HSL was inhibited at high NH_(4)^(+)-N levels of 200 mg/L.The findings provided the significant application potential of QS system for BNR when facing toxic compound shock threats.展开更多
Quorum quenching (QQ)-based strategies are efficient for biofouling control.However,the feasibility of using QQ bacteria in antibiotic-stressed membrane bioreactors (MBRs) remains unknown.In this study,we isolated thr...Quorum quenching (QQ)-based strategies are efficient for biofouling control.However,the feasibility of using QQ bacteria in antibiotic-stressed membrane bioreactors (MBRs) remains unknown.In this study,we isolated three novel QQ strains (Bacillus sp.QX01 and QX03,Delftia sp.QX14) from the activated sludge of an actual MBR.They can degrade 11 N-acylhomoserine lactones (AHLs) with high efficiencies and rates through intracellular QQ pathways involving putative acylases and lactonases.Running two lab-scale MBRs,we found that introducing antibiotics (sulfamethoxazole,azithromycin,and ciprofloxacin,each at100μg/L) shortened the fouling cycle by 71.4%.However,the immobilized inoculation of QX01 into one MBR extended the fouling cycle by 1.5-2.0 times.Quantitative detection revealed that QX01 significantly reduced the concentrations of two AHLs (C4-HSL and C8-HSL),which were positively correlated with the contents of extracellular polymeric substances(EPS)(Pearson’s r=0.62-0.83,P<0.01).This suggests that QX01 could perform its QQ activity robustly under antibiotic stress,thereby inhibiting EPS production (proteins especially) and biofilm formation.Moreover,QX01 notably altered the succession patterns of both sludge and fouling communities,with more pronounced effects on abundant taxa.Genera associated with AHL synthesis and EPS production,such as Terrimonas and Rhodobacter,were significantly depleted,contributing to the mitigated biofouling.Additionally,QX01 increased the bacterial community diversity (evenness especially),which was inhibited by antibiotics.Overall,we demonstrate that the novel QQ bacteria could be effective for biofouling control in antibiotic-stressed MBRs,though future work is needed to develop practical approaches for prolonging QQ activity.展开更多
Pseudomonas aeruginosa,recognized for its biofilm production and secretion of virulence factors,posing a severe threat in areas such as clinical infections,food contamination,and marine biofouling.To address this,a ne...Pseudomonas aeruginosa,recognized for its biofilm production and secretion of virulence factors,posing a severe threat in areas such as clinical infections,food contamination,and marine biofouling.To address this,a new type of zinc-binding peptide(CSSP-Zn)was prepared from crimson snapper scales peptides(CSSP)and goslarite,and its antibacterial and anti-quorum-sensing activities toward P.aeruginosa PAO1 were exploited.Results indicated that CSSP-Zn induced planktonic strain PAO1 membrane injury via inhibiting expression levels of cell integrity genes,targeting microbial-specific membrane constituents,disrupting proton motive force,and causing metabolic disturbances.Meanwhile,CSSP-Zn decreased virulence factors pyocyanin,protease and rhamnolipid secretion,while considerably inhibiting quorum sensing-related genes(las,pqs and rhl)expression and decreasing bacterial abundance and pathogenicity in fish models.Moreover,CSSP-Zn not only effectively hindered biofilm formation but also disassembled preformed ones,thus disrupting biofilm topology.Taken together,utilizing food byproducts to obtain CSSP-Zn could help recycle food resources and provide insight into controlling planktonic and biofilm strain PAO1 contamination.展开更多
制造技术协会(MTA)与The Quorum Principle宣布建立战略合作伙伴关系,旨在为MTA成员提供更强的协作能力,并在全球市场中获得竞争优势。The Quorum Principle是一家专注于区块链技术和分布式账本解决方案的公司,主要为企业提供基于区块...制造技术协会(MTA)与The Quorum Principle宣布建立战略合作伙伴关系,旨在为MTA成员提供更强的协作能力,并在全球市场中获得竞争优势。The Quorum Principle是一家专注于区块链技术和分布式账本解决方案的公司,主要为企业提供基于区块链的定制化服务。其核心业务围绕Hyperledger Quorum(一个由Linux基金会支持的企业级区块链框架)的开发、部署和优化,帮助各行业客户(尤其是制造业、供应链、金融等)通过区块链技术实现数据共享、流程自动化和协作创新。展开更多
The detection of acyl homoserine lactones（AHLs） in activated sludge is essential for clarifying their function in wastewater treatment processes. An LC–MS/MS method was developed for the detection of AHLs in both t...The detection of acyl homoserine lactones（AHLs） in activated sludge is essential for clarifying their function in wastewater treatment processes. An LC–MS/MS method was developed for the detection of AHLs in both the aqueous and solid phases of activated sludge. In addition, the effects of proteases and extracellular polymeric substances（EPS） on the detection of AHLs were evaluated by adding protease inhibitors and extracting EPS,respectively. Recoveries of each AHL were improved by adding 50 μL of protease inhibitor,and recoveries were also improved from 0 to 56.9% to 24.2%–105.8% by EPS extraction.Applying the developed method to determine the type and concentration of AHLs showed that C4-HSL, C6-HSL, C8-HSL and 3-oxo-C8-HSL were widely detected in a suspended activated sludge system. The dominant AHL was C8-HSL, with a highest concentration of304.3 ng/L. C4-HSL was mainly distributed in the aqueous phase, whereas C6-HSL, C8-HSL and 3-oxo-C8-HSL were preferentially distributed in the sludge phase.展开更多
Quorum sensing （QS） is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, includi...Quorum sensing （QS） is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, including an intact QS system 2 that is stimulated by the cyclic AMP （cAMP）-cAMP receptor protein （CRP） complex and a partial QS system 1 that consists of SdiA （suppressor of cell division inhibitor） responding to signals generated by other microbial species. The relationship between QS system 1 and system 2 in E. coli, however, remains obscure. Here, we show that an EAL domain protein, encoded by ydiV, and cAMP are involved in the interaction between the two QS systems in E. coli. Expression of sdiA and ydiV is inhibited by glucose. SdiA binds to the ydiV promoter region in a dose-dependent, but nonspecific, manner; extracellular autoinducer 1 from other species stimulates ydiV expression in an sdiA-depen- dent manner. Furthermore, we discovered that the double sdiA-ydiV mutation, but not the single mutation, causes a 2-fold decrease in intracellular cAMP concentration that leads to the inhibition of QS system 2. These results indicate that signaling pathways that respond to important environmental cues, such as autoinducers and glucose, are linked together for their control in E. coli.展开更多
Background:To investigate the effect of flavaspidic acid BB(BB)on biofilms and quorum sensing-related genes of drug-resistant Staphylococcus epidermidis(SE)and to provide a theoretical basis for the development of BB ...Background:To investigate the effect of flavaspidic acid BB(BB)on biofilms and quorum sensing-related genes of drug-resistant Staphylococcus epidermidis(SE)and to provide a theoretical basis for the development of BB as a new type of quorum sensing inhibitor.Methods:The microdilution method was applied to screen 15 clinical isolates of S.epidermidis for drug-resistant S.epidermidis to be used as the test strain.The effects of BB on the biofilms of drug-resistant S.epidermidis at different growth stages were studied using the cell counting kit-8 assay and scanning electron microscopy.The gene expression of sigB,sarA,and luxS,regulators involved in quorum sensing of biofilm formation,was measured by PCR.Results:The minimum inhibitory concentrations of BB against 15 clinical strains of S.epidermidis ranged 11.67-66.67μg/mL.BB significantly inhibited biofilm formation by drug-resistant SE06 in the aggregation and maturation stages,with an activity superior to those of mupirocin and fusidic acid(P<0.05).At 40μg/mL,BB reduced the secretion of extracellular polymers and promoted the disruption of biofilm structure.At 80μg/mL,BB specifically interfered with the quorum sensing system of drug-resistant SE06 by downregulating sarA and luxS,thereby inhibiting this microbe’s biofilm formation.Conclusion:BB exhibited strong inhibitory activity against SE06 by suppressing biofilm formation and downregulating quorum sensing-related genes and was identified as a new potential quorum sensing inhibitor against S.epidermidis.展开更多
基金Supported by the National Natural Science Foundation of China (70771043, 60873225, 60773191)
文摘Quorum system is a preferable model to construct distributed access control architecture, but not all quorum system can satisfy the requirements of distributed access control architecture. Aiming at the dependable problem of authorization server in distributed system and combining the requirements of access control, a set of criterions to select and evaluate quorum system is presented. The scheme and algorithm of constructing an authorization server system based on Paths quorum system are designed, and the integrated sys- tem performance under some servers attacked is fully analyzed. Role-based access control on the Web implemented by this scheme is introduced. Analysis shows that with certain node failure probability, the scheme not only has high dependability but also can satisfy the special requirements of distributed access control such as real-time, parallelism, and consistency of security policy.
基金supported by the National Natural Science Foundation of China (60774091)
文摘Quorum systems have been used to solve the problem of data consistency in distributed fault-tolerance systems. But when intrusions occur, traditional quorum systems have some disadvantages. For example, synchronous quorum systems are subject to DOS attacks, while asynchronous quorum systems need a larger system size （at least 3f＋1 for generic data, and f fewer for self-verifying data）. In order to solve the problems above, an intrusion-tolerance quorum system （ITQS） of hybrid time model based on trust timely computing base is presented （TTCB）. The TTCB is a trust secure real-time component inside the server with a well defined interface and separated from the operation system. It is in the synchronous communication environment while the application layer in the server deals with read-write requests and executes update-copy protocols asynchronously. The architectural hybridization of synchrony and asynchrony can achieve the data consistency and availability correctly. We also build two kinds of ITQSes based on TTCB, i.e., the symmetrical and the asymmetrical TTCB quorum systems. In the performance evaluations, we show that TTCB quorum systems are of smaller size, lower load and higher availability.
文摘Rapid developments in network systems of business service have resulted in more reliance on distributed computing, typified by “subscriber/push” architectures. Unfortunately, frequent and unexpectable network failures were routine, and downtime was not in hours, but in days. High availability has become the most important factor decreasing business risk and improving Quality of Service. Cluster technology has solved the non-stop problem on Local Area Network. However, most technologies including cluster today fail to ensure the non-stop Internet service based on Routers. With good performance on high availability and fault tolerance, quorum systems are very suitable for application to distributed business service networks. In this work, we modeled and developed a non-stop Internet service system based on a new quorum system, circle quorum system, for Boston Mutual Fund Broker, US. With five protocols, it provided highly available data services for clients on Internet.
文摘The communication system known as quorum sensing (QS) in gram-negative bacteria regulates biofilm formation and many other functions. The particularity of Pseudoalteromonas ulvae TC14 seems to be the absence of a LuxI inducer, and therefore the lack of production of small molecules of Acyl homoserine lactone (AHL). Previous studies had shown that it does not harbor the inducer of the regulatory molecule (AHL). Nevertheless, it is able to regulate these same functions (biofilm, violacein) via AHLs. This could mean the presence of specific receptors for these induction molecules, belonging to the LuxR family. The aim of this study was to test these hypotheses using molecular analysis. Genome sequencing of the P. ulvae TC14 strain was carried out by Molecular Research LP (MR DNA), using the Illumina Hiseq 2500 method. The results revealed the presence of 2,293,242 base pairs, i.e. 100% of the genomic volume. The number of coding gene sequences was 1983, and the Guanine + Cytosine (G+C) percentage of the base number was 41.55%, revealing stability in the sequenced genome. In order to verify the identity of the sequenced genome, a phylogenetic analysis based on RNA16S was carried out. This analysis resulted in 93% homology with the previously sequenced and characterized species Pseudoalteromonas tunicata, showing that it belongs to the genus Pseudoalteromonas. To these comparative results should be added those derived from genome analysis based on nucleotide percentage using the tools available at https://img.jgi.doe.gov/. The results showed that Pseudoalteromonas tunicata D2 has the highest percentage nucleotide identity (ANI) (75.7913%), followed by Pseudoalteromonas flavipulchra NCIMB2033 (72.2736%) and Pseudoalteromonas phenolica KCTC 12086 (71.6685%). Next, the search for the various genes involved in QS was carried out using sequence comparisons via the BLAST method. For LuxI, sequence templates from the genomes of Vibrio, Chromobacterium, Shewanella or even other Pseudoalteromonas species were screened against the TC14 genome. This yielded no conclusive results synonymous with the non-presence of LuxI in TC14 as assumed by previous research. The search for LuxR, on the other hand, gave rise to the presence of eight presumptive sequences. Molecular characterization of the presumptive LuxR sequences was carried out to assess their gene expression. This characterization showed expression of these LuxR homologous sequences in a range from o.11 to 5.33 picograms (pg). Even if these sequences were not analyzed in depth, the retro-transcription technique nevertheless showed a minimum of activity, which could enable us to distinguish them from inactive sequences. The next step was to compare the LuxRs found in TC14 with the so-called Solo LuxRs, which act autonomously. This study shows that P. ulvae TC14 is a bacterium with a particular LuxR-based communication system.
基金supported by grants from the National Natural Science Foundation of China(32000091)General Projects of Natural Science Research in Universities of Jiangsu Province(20KJB180019)Jiangsu Youth Talent Promotion Project(TJ-2021-066)。
文摘We assessed the quorum sensing(QS)inhibitory impact of sesamol against the foodborne bacterium Pseudomonas aeruginosa.At concentrations ranging from 50 to 200μg/mL,sesamol significantly inhibited the production of virulence factors such as protease,elastase,pyocyanin,rhamnolipid,and chemotaxis,and improved the susceptibility of bacterial and biofilm cells to colistin.Integrated transcriptomics,metabolomics,and docking analyses indicated that exposure to sesamol destroyed the QS system and down-regulated the expressions of genes encoding virulence and antioxidant enzymes.The down-regulation of genes encoding antioxidant enzymes intensified oxidative stress,as demonstrated by the enhancement of reactive oxygen species and H_(2)O_(2).The enhanced oxidative stress changed the components of the cell membrane,improved its permeability,and ultimately enhanced the susceptibility of bacterial and biofilm cells to colistin.Moreover,exposure to sesamol also led to the disorder of amino acid metabolism and energy metabolism,eventually attenuating the pathogenicity of P.aeruginosa.These findings indicated that sesamol can function as a potent anti-virulence agent to defend against food spoilage caused by P.aeruginosa.
基金Biotechnology Institute and the MnDrive initiative(to MHE)。
文摘Background:Over the past 50 years,the incidence of obesity has gradually increased,necessitating investigation into the multifactorial contributors to this disease,including the gut microbiota.Bacteria within the human gut microbiome communicate using a density-dependent process known as quorum sensing(QS),in which autoinducer(AI)molecules(e.g.,N-acyl-homoserine lactones[AHLs])are produced to enable bacterial interactions and regulate gene expression.Methods:We aimed to disrupt QS using quorum quenching(QQ)lactonases GcL and SsoPox,which cleave AHL signaling molecules in a taxa-specific manner based on differing enzyme affinities for different substrates.We hypothesized that QQ hinders signals from obesity-associated pathobionts,thereby slowing or preventing obesity.Results:In a murine model of dietinduced obesity,we observed GcL and SsoPox treatments have separate sex-dependent and dose-dependent effects on intestinal community composition and diversity.Notably,male mice given 2 mg/mL SsoPox exhibited significant changes in the relative abundances of gram-negative taxa,including Porphyromonadaceae,Akkermansiaceae,Muribaculaceae,and Bacteroidales(Kruskal-Wallis p<0.001).Additionally,we used covariance matrix network analysis to model bacterial taxa co-occurrence due to QQ enzyme administration.There were more associations among taxa in control mice,particularly among gram-negative bacteria,whereas mice receiving SsoPox had the fewest associations.Conclusions:Overall,our study establishes proof of concept that QQ is a targetable strategy for microbial control in vivo.Further characterization and dosage optimization of QQ enzymes are necessary to harness their therapeutic capability for the treatment of chronic microbial-associated diseases.
基金Research on the Resistance Mechanism of Carbapenem-Resistant Escherichia coli in Patients with Urosepsis Based on Bacterial Droplet Single-Cell RNA Sequencing(Project No.:MTyk2024-34,2024.01-2026-12)。
文摘Quorum sensing(QS)represents a mechanism through which bacteria engage in communication via chemical signals,a phenomenon prevalent across diverse bacterial species.Recent investigations have elucidated that QS signaling pathways are pivotal in governing bacterial physiological processes,collective behaviors,and the emergence of drug resistance.Escherichia coli(E.coli),a prominent pathogenic bacterium,is increasingly exhibiting severe drug resistance issues,posing substantial hurdles for clinical interventions.Presently,a burgeoning body of research is exploring the connection between QS signaling pathways and the drug resistance mechanisms in E.coli,unveiling the coordinating function of QS within bacterial communities and its influence on antibiotic resistance.Despite some research advancements,the precise mechanisms underlying the QS signaling pathway remain ambiguous,and its potential applications are somewhat constrained.This article endeavors to systematically review the research progress concerning the QS signaling pathway in the context of clinical drug resistance mechanisms in E.coli,delving into its potential clinical applications and future research avenues,with the aim of offering novel insights and strategies to counteract drug resistance.
基金supported by the National Natural Science Foundation of China(No.52270119).
文摘The inhibitory effects of zinc oxide nanoparticles(ZnO NPs)and impacts of N-acylhomoserine lactone(AHL)-based quorum sensing(QS)on biological nitrogen removal(BNR)performance have beenwell-investigated.However,the effects of ammonia nitrogen(NH_(4)^(+)-N)concentrations on NP toxicity and AHL regulation have seldom been addressed yet.This study consulted on the impacts of ZnO NPs on BNR systems when high NH_(4)^(+)-N concentrationwas available.The synergistic toxic effects of high-strength NH_(4)^(+)-N(200 mg/L)and ZnO NPs resulted in decreased ammonia oxidation rates and dropped the nitrogen removal efficiencies by 17.5%±0.2%.The increased extracellular polymeric substances(EPS)production was observed in response to the high NH_(4)^(+)-N and ZnO NP stress,which indicated the defensemechanism against the toxic effects in the BNR systemswas stimulated.Furthermore,the regulatory effects of exogenous N-decanoyl-homoserine lactone(C_(10)-HSL)-mediated QS system on NP-stressed BNR systems were revealed to improve the BNR performance under different NH_(4)^(+)-N concentrations.The C_(10)-HSL regulated the intracellular reactive oxygen species levels,denitrification functional enzyme activities,and antioxidant enzyme activities,respectively.This probably synergistically enhanced the defense mechanism against NP toxicity.However,compared to the low NH_(4)^(+)-N concentration of 60 mg/L,the efficacy of C_(10)-HSL was inhibited at high NH_(4)^(+)-N levels of 200 mg/L.The findings provided the significant application potential of QS system for BNR when facing toxic compound shock threats.
基金supported by the National Natural Science Foundation of China (Nos.51938001 and 52300073)。
文摘Quorum quenching (QQ)-based strategies are efficient for biofouling control.However,the feasibility of using QQ bacteria in antibiotic-stressed membrane bioreactors (MBRs) remains unknown.In this study,we isolated three novel QQ strains (Bacillus sp.QX01 and QX03,Delftia sp.QX14) from the activated sludge of an actual MBR.They can degrade 11 N-acylhomoserine lactones (AHLs) with high efficiencies and rates through intracellular QQ pathways involving putative acylases and lactonases.Running two lab-scale MBRs,we found that introducing antibiotics (sulfamethoxazole,azithromycin,and ciprofloxacin,each at100μg/L) shortened the fouling cycle by 71.4%.However,the immobilized inoculation of QX01 into one MBR extended the fouling cycle by 1.5-2.0 times.Quantitative detection revealed that QX01 significantly reduced the concentrations of two AHLs (C4-HSL and C8-HSL),which were positively correlated with the contents of extracellular polymeric substances(EPS)(Pearson’s r=0.62-0.83,P<0.01).This suggests that QX01 could perform its QQ activity robustly under antibiotic stress,thereby inhibiting EPS production (proteins especially) and biofilm formation.Moreover,QX01 notably altered the succession patterns of both sludge and fouling communities,with more pronounced effects on abundant taxa.Genera associated with AHL synthesis and EPS production,such as Terrimonas and Rhodobacter,were significantly depleted,contributing to the mitigated biofouling.Additionally,QX01 increased the bacterial community diversity (evenness especially),which was inhibited by antibiotics.Overall,we demonstrate that the novel QQ bacteria could be effective for biofouling control in antibiotic-stressed MBRs,though future work is needed to develop practical approaches for prolonging QQ activity.
文摘Pseudomonas aeruginosa,recognized for its biofilm production and secretion of virulence factors,posing a severe threat in areas such as clinical infections,food contamination,and marine biofouling.To address this,a new type of zinc-binding peptide(CSSP-Zn)was prepared from crimson snapper scales peptides(CSSP)and goslarite,and its antibacterial and anti-quorum-sensing activities toward P.aeruginosa PAO1 were exploited.Results indicated that CSSP-Zn induced planktonic strain PAO1 membrane injury via inhibiting expression levels of cell integrity genes,targeting microbial-specific membrane constituents,disrupting proton motive force,and causing metabolic disturbances.Meanwhile,CSSP-Zn decreased virulence factors pyocyanin,protease and rhamnolipid secretion,while considerably inhibiting quorum sensing-related genes(las,pqs and rhl)expression and decreasing bacterial abundance and pathogenicity in fish models.Moreover,CSSP-Zn not only effectively hindered biofilm formation but also disassembled preformed ones,thus disrupting biofilm topology.Taken together,utilizing food byproducts to obtain CSSP-Zn could help recycle food resources and provide insight into controlling planktonic and biofilm strain PAO1 contamination.
文摘制造技术协会(MTA)与The Quorum Principle宣布建立战略合作伙伴关系,旨在为MTA成员提供更强的协作能力,并在全球市场中获得竞争优势。The Quorum Principle是一家专注于区块链技术和分布式账本解决方案的公司,主要为企业提供基于区块链的定制化服务。其核心业务围绕Hyperledger Quorum(一个由Linux基金会支持的企业级区块链框架)的开发、部署和优化,帮助各行业客户(尤其是制造业、供应链、金融等)通过区块链技术实现数据共享、流程自动化和协作创新。
基金supported by the National Key Research and Development Program of China for International Science and Innovation Cooperation Major Project between Governments(No.2016YFE0118800)the Shenzhen Science and Technology Development Funding-Fundamental Research Plan(No.JCYJ20150331151358156)
文摘The detection of acyl homoserine lactones（AHLs） in activated sludge is essential for clarifying their function in wastewater treatment processes. An LC–MS/MS method was developed for the detection of AHLs in both the aqueous and solid phases of activated sludge. In addition, the effects of proteases and extracellular polymeric substances（EPS） on the detection of AHLs were evaluated by adding protease inhibitors and extracting EPS,respectively. Recoveries of each AHL were improved by adding 50 μL of protease inhibitor,and recoveries were also improved from 0 to 56.9% to 24.2%–105.8% by EPS extraction.Applying the developed method to determine the type and concentration of AHLs showed that C4-HSL, C6-HSL, C8-HSL and 3-oxo-C8-HSL were widely detected in a suspended activated sludge system. The dominant AHL was C8-HSL, with a highest concentration of304.3 ng/L. C4-HSL was mainly distributed in the aqueous phase, whereas C6-HSL, C8-HSL and 3-oxo-C8-HSL were preferentially distributed in the sludge phase.
文摘Quorum sensing （QS） is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, including an intact QS system 2 that is stimulated by the cyclic AMP （cAMP）-cAMP receptor protein （CRP） complex and a partial QS system 1 that consists of SdiA （suppressor of cell division inhibitor） responding to signals generated by other microbial species. The relationship between QS system 1 and system 2 in E. coli, however, remains obscure. Here, we show that an EAL domain protein, encoded by ydiV, and cAMP are involved in the interaction between the two QS systems in E. coli. Expression of sdiA and ydiV is inhibited by glucose. SdiA binds to the ydiV promoter region in a dose-dependent, but nonspecific, manner; extracellular autoinducer 1 from other species stimulates ydiV expression in an sdiA-depen- dent manner. Furthermore, we discovered that the double sdiA-ydiV mutation, but not the single mutation, causes a 2-fold decrease in intracellular cAMP concentration that leads to the inhibition of QS system 2. These results indicate that signaling pathways that respond to important environmental cues, such as autoinducers and glucose, are linked together for their control in E. coli.
文摘Background:To investigate the effect of flavaspidic acid BB(BB)on biofilms and quorum sensing-related genes of drug-resistant Staphylococcus epidermidis(SE)and to provide a theoretical basis for the development of BB as a new type of quorum sensing inhibitor.Methods:The microdilution method was applied to screen 15 clinical isolates of S.epidermidis for drug-resistant S.epidermidis to be used as the test strain.The effects of BB on the biofilms of drug-resistant S.epidermidis at different growth stages were studied using the cell counting kit-8 assay and scanning electron microscopy.The gene expression of sigB,sarA,and luxS,regulators involved in quorum sensing of biofilm formation,was measured by PCR.Results:The minimum inhibitory concentrations of BB against 15 clinical strains of S.epidermidis ranged 11.67-66.67μg/mL.BB significantly inhibited biofilm formation by drug-resistant SE06 in the aggregation and maturation stages,with an activity superior to those of mupirocin and fusidic acid(P<0.05).At 40μg/mL,BB reduced the secretion of extracellular polymers and promoted the disruption of biofilm structure.At 80μg/mL,BB specifically interfered with the quorum sensing system of drug-resistant SE06 by downregulating sarA and luxS,thereby inhibiting this microbe’s biofilm formation.Conclusion:BB exhibited strong inhibitory activity against SE06 by suppressing biofilm formation and downregulating quorum sensing-related genes and was identified as a new potential quorum sensing inhibitor against S.epidermidis.
