群体猝灭技术在控制MBR生物污染中的研究进展

膜生物反应器(MBR)广泛用于处理市政污水,但膜污染仍是MBR的应用瓶颈。基于微生物群体感应(QS)理论的群体猝灭(QQ)技术是一种具有较好前景的膜污染控制方法。QQ技术可干扰微生物的QS系统,进而抑制胞外聚合物的分泌和生物膜的形成,从根本上达到控制MBR生物污染的目的。对利用QQ技术控制MBR生物污染的研究进展进行总结,提出该技术面临的挑战,并对今后采用QQ技术减缓膜污染的研究进行展望。     

应用群体感应淬灭技术控制MBR膜污染的研究进展

膜生物反应器(MBR)被广泛应用于污水的深度处理和回用。然而,膜表面的生物污染一直是MBR应用中的难题,至今仍未得到有效解决。研究结果表明,生物膜的形成与细胞间的群体感应(QS)有关,因此,通过干扰QS系统而阻止生物膜形成的群体淬灭(QQ)技术有望从根本上有效减缓MBR膜表面的生物污染。文中综述了微生物信号分子、QS机制以及各种控制MBR膜污染的QQ方法,为MBR膜生物污染控制技术的发展提供了相关信息。     

基于群体淬灭理论MBR减缓膜污染研究进展

膜生物反应器(membrane bioreactor,MBR)已成为一个十分有前景的废水处理工艺,该工艺具有出水水质好、占地面积小等优势.然而,由于微生物附着在膜表面而发生的生物污染现象,致使出水通量下降,限制了MBR的大规模推广应用.最近,一种新兴的、基于群体感应(quorum sensing,QS)的群体淬灭(quorum quenching,QQ)技术在延缓MBR膜污染领域的应用备受关注.QQ通过干扰群体感应系统而阻止其所依赖信号分子的基因表达,从而可有效抑制膜表面生物膜的形成.本文首先介绍了群体感应机理,并根据不同的群体淬灭物质,归纳总结了群体淬灭技术在延缓MBR膜污染的最新研究进展,最后对该领域的研究进行了展望.     

膜生物反应器生物污染及其控制

综述了膜生物反应器(MBR)中生物污染的机理,以及影响生物污染的各种因素,包括水动力学条件、膜组件结构、膜材料及其性质、污泥特性、操作条件和环境条件等。并从膜模型设计、反冲洗、化学清洗和MBR系统的设计优化4个方面介绍了生物污染的控制措施。     

基于群体感应相关菌群分析的HMBR膜污染控制研究

微生物群体感应现象已经在污水处理中被验证并应用于膜污染控制,但是其在复合式膜生物反应器（HMBR中的膜污染控制研究鲜有报道。构建了HMBR污水处理系统,并在不同污泥龄（SRT=10、20、30 d）下运行HMBR设备,通过分析出水水质考察HMBR污水处理系统对污染物的去除效能;采用高通量测序检测群体感应相关菌群的群落结构,并结合跨膜压差、信号分子浓度深入解析群体感应调控HMBR膜污染的机理。实验结果表明,HMBR在SRT=30 d的工况下出水水质最好,膜组件运行周期最长,为最佳工况;HMBR内检测到多种群体感应猝灭（QQ）菌,其中从单胞菌科（Comamonas）、黄单胞菌科（Xanthomonadacea）和厌氧绳菌科（Anaerolineaceae）相对丰度较大;在长SRT下QQ菌比群体感应（QS）菌相对丰度更具优势,有助于降低HMBR内部信号分子的浓度,阻碍EPS分泌过程的正常进行,从而优化膜组件运行周期,因此通过延长SRT来抑制群体感应强度是一种有效的HMBR膜污染调控手段。     

基于群体感应调控细菌生物膜形成研究进展

近些年来,许多研究都表明细菌等微生物之间存在群体感应现象(quorum sensing,QS).许多细菌都能合成并分泌自诱导物质来调控基因的表达调控生物膜的形成,以此保证细菌在生长过程中适应新的环境.生物膜(biofilm)的存在与细菌的抗逆能力有很大的关联,基于驱散群体感应抑制生物膜的形成也成了目前的研究热点之一.本...     

陶瓷膜的生物污染控制及其抑菌改性

陶瓷膜因其具有耐高温高压、耐腐蚀、耐有机溶剂、膜通量高和使用寿命长等优点被广泛运用于水处理、食品饮料、医药、化工、电子以及环保等领域.但陶瓷膜的污染尤其是生物污染成为制约其实际运用的-个重要因素,因此陶瓷膜的抑菌改性越来越受到人们关注.本文论述了陶瓷膜生物污染过程及其控制方法,介绍了常见的无机抑菌材料和目前抑菌陶瓷膜的相关研究现状和趋势.     

反渗透膜生物污染的研究进展

综述了近年来关于反渗透膜生物污染的研究进展。首先介绍了反渗透膜生物污染的机理,包括微生物与膜表面的吸附作用以及外界因素对微生物沉积的影响;然后阐述了如何监测和预警生物污染;并讨论了对生物污染的控制和预防方法,包括预处理、膜表面改性、膜清洗以及微生物群体感应抑制。     

压力驱动膜生物污染研究进展

近年来膜分离技术在废水处理、水污染防治和水资源综合利用等方面被广泛应用,膜污染问题也引起了人们的广泛关注。本文总结了近年来微生物及微生物代谢产物引发的膜污染形成机制及研究现状,提出了今后膜生物污染控制的研究方向和可能措施。     

膜生物反应器污水处理过程中膜生物污染的研究进展

本文论述了用于污水处理的膜生物反应器的膜污染及其影响因素，同时，重点分析了膜生物污染的形成机理、微生物粘附和繁殖生长，并讨论了膜的生物污染现象、形成过程、危害以及防治措施。     

Quorum Sensing and Phytochemicals

Most infectious diseases are caused by bacteria, which proliferate within quorum sensing (QS)-mediated biofilms. Efforts to block QS in bacteria and disrupt biofilms have enabled the identification of bioactive molecules that are also produced by plants. This mini review primarily focuses on natural QS inhibitors, which display potential for treating bacterial infections and also enhance the safety of food supply.     

Quorum Quenching Enzymes and Their Application in Degrading Signal Molecules to Block Quorum Sensing-Dependent Infection

With the emergence of antibiotic-resistant strains of bacteria, the available options for treating bacterial infections have become very limited, and the search for a novel general antibacterial therapy has received much greater attention. Quorum quenching can be used to control disease in a quorum sensing system by triggering the pathogenic phenotype. The interference with the quorum sensing system by the quorum quenching enzyme is a potential strategy for replacing traditional antibiotics because the quorum quenching strategy does not aim to kill the pathogen or limit cell growth but to shut down the expression of the pathogenic gene. Quorum quenching enzymes have been identified in quorum sensing and non-quorum sensing microbes, including lactonase, acylase, oxidoreductase and paraoxonase. Lactonase is widely conserved in a range of bacterial species and has variable substrate spectra. The existence of quorum quenching enzymes in the quorum sensing microbes can attenuate their quorum sensing, leading to blocking unnecessary gene expression and pathogenic phenotypes. In this review, we discuss the physiological function of quorum quenching enzymes in bacterial infection and elucidate the enzymatic protection in quorum sensing systems for host diseases and their application in resistance against microbial diseases.     

Intra-Species Bacterial Quorum Sensing Studied at Single Cell Level in a Double Droplet Trapping System

In this paper, we investigated the intra-species bacterial quorum sensing at the single cell level using a double droplet trapping system. Escherichia coli transformed to express the quorum sensing receptor protein, LasR, were encapsulated in microdroplets that were positioned adjacent to microdroplets containing the autoinducer, N-(3-oxododecanoyl)- l-homoserine lactone (OdDHL). Functional activation of the LasR protein by diffusion of the OdDHL across the droplet interface was measured by monitoring the expression of green fluorescent protein (GFP) from a LasR-dependent promoter. A threshold concentration of OdDHL was found to induce production of quorum-sensing associated GFP by E. coli. Additionally, we demonstrated that LasR-dependent activation of GFP expression was also initiated when the adjacent droplets contained single E. coli transformed with the OdDHL synthase gene, LasI, representing a simple quorum sensing circuit between two droplets.     

动态膜生物反应器技术进展

该文介绍了动态膜生物反应器(dynamic membrane bio-reactor,DMBR)的成膜机理、膜结构形态、过滤模型及阻力特性,讨论了基网选择、污泥浓度(MLSS)、出水水头、错流速度对动态膜生物反应器运行特性的影响,对DMBR的应用前景进行了展望。     

陶瓷分离膜支撑体制备技术研究进展

介绍了几种无机陶瓷支撑体的制备方法,评述了这些方法的优缺点.探讨了制备过程中的几个主要因素对支撑体的孔径大小及其分布、空隙率、机械强度等重要参数的影响.并指出目前无机陶瓷支撑体的研究过程中存在的主要问题及今后的研究方向.     

The Structural Determinants Accounting for the Broad Substrate Specificity of the Quorum Quenching Lactonase GcL

Quorum quenching lactonases are enzymes capable of hydrolyzing lactones, including N-acyl homoserine lactones (AHLs). AHLs are molecules known as signals in bacterial communication dubbed quorum sensing. Bacterial signal disruption by lactonases was previously reported to inhibit behavior regulated by quorum sensing, such as the expression of virulence factors and the formation of biofilms. Herein, we report the enzymatic and structural characterization of a novel lactonase representative from the metallo-β-lactamase superfamily, dubbed GcL. GcL is a broad spectrum and highly proficient lactonase, with k_cat/K_M values in the range of 10⁴ to 10⁶ m ⁻¹ s⁻¹. Analysis of free GcL structures and in complex with AHL substrates of different acyl chain length, namely, C4-AHL and 3-oxo-C12-AHL, allowed their respective binding modes to be elucidated. Structures reveal three subsites in the binding crevice: 1) the small subsite where chemistry is performed on the lactone ring; 2) a hydrophobic ring that accommodates the amide group of AHLs and small acyl chains; and 3) the outer, hydrophilic subsite that extends to the protein surface. Unexpectedly, the absence of structural accommodation for long substrate acyl chains seems to relate to the broad substrate specificity of the enzyme.