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Oe Hideo Masahiro Kohashi Kazuo Iwai 《Bioscience, biotechnology, and biochemistry》2013,77(7):1887-1888
N-Acylhomoserine lactones (AHLs) are used as quorum-sensing signal molecules by many gram-negative bacteria. We have reported that Shewanella sp. strain MIB015 degrades AHLs. In the present study, we cloned the aac gene from MIB015 by PCR with specific primers based on the aac gene in Shewanella oneidensis strain MR-1, which showed high homology with the known AHL-acylases. Escherichia coli expressing Aac showed high degrading activity of AHLs with long acyl chains. HPLC analysis revealed that Aac worked as AHL-acylase, which hydrolyzed the amide bond of AHL. In addition, expression of Aac in fish pathogen Vibrio anguillarum markedly reduced AHL production and biofilm formation. In conclusion, this study indicates that Aac might be effective in quenching quorum sensing of fish pathogens. 相似文献
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丛枝菌根(Arbuscular mycorrhiza,AM)共生是自然界中普遍存在的一种互惠共生现象,对促进土壤生态系统物质循环及维持生态系统稳定具有重要的意义。AM共生体的建立需要AM真菌和宿主植物间一系列复杂的信号识别、交换和传导。本文总结近年来相关文献,从AM共生体形成前期及AM共生体形成期两个阶段,分别综述了信号物质的生物合成过程、调控过程及其作用机制,希望有助于进一步认识AM共生体建成过程,同时通过分析当前研究工作的不足及未来研究动向,期望推动相关研究工作。 相似文献
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Ashwani Kumar Joanna F. Dames Aditi Gupta Satyawati Sharma Jack A. Gilbert Parvaiz Ahmad 《Critical reviews in biotechnology》2015,35(4):461-474
Arbuscular mycorrhizal fungi (AMF) form widespread symbiotic associations with 80% of known land plants. They play a major role in plant nutrition, growth, water absorption, nutrient cycling and protection from pathogens, and as a result, contribute to ecosystem processes. Salinity stress conditions undoubtedly limit plant productivity and, therefore, the role of AMF as a biological tool for improving plant salt stress tolerance, is gaining economic importance worldwide. However, this approach requires a better understanding of how plants and AMF intimately interact with each other in saline environments and how this interaction leads to physiological changes in plants. This knowledge is important to develop sustainable strategies for successful utilization of AMF to improve plant health under a variety of stress conditions. Recent advances in the field of molecular biology, “omics” technology and advanced microscopy can provide new insight about these mechanisms of interaction between AMF and plants, as well as other microbes. This review mainly discusses the effect of salinity on AMF and plants, and role of AMF in alleviation of salinity stress including insight on methods for AMF identification. The focus remains on latest advancements in mycorrhizal research that can potentially offer an integrative understanding of the role of AMF in salinity tolerance and sustainable crop production. 相似文献
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Bacteria are able to sense their population's density through a cell–cell communication system, termed ‘quorum sensing’ (QS). This system regulates gene expression in response to cell density through the constant production and detection of signalling molecules. These molecules commonly act as auto‐inducers through the up‐regulation of their own synthesis. Many pathogenic bacteria, including those of plants, rely on this communication system for infection of their hosts. The finding that the countering of QS‐disrupting mechanisms exists in many prokaryotic and eukaryotic organisms offers a promising novel method to fight disease. During the last decade, several approaches have been proposed to disrupt QS pathways of phytopathogens, and hence to reduce their virulence. Such studies have had varied success in vivo, but most lend promising support to the idea that QS manipulation could be a potentially effective method to reduce bacterial‐mediated plant disease. This review discusses the various QS‐disrupting mechanisms found in both bacteria and plants, as well as the different approaches applied artificially to interfere with QS pathways and thus protect plant health. 相似文献
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《Bioscience, biotechnology, and biochemistry》2013,77(12):2436-2440
N-Acylhomoserine lactones (AHLs) function as quorum-sensing signaling molecules in many Gram-negative bacteria. We isolated a total of 672 bacterial strains from activated sludge obtained from seven sewage treatment plants in Tochigi Prefecture, Japan, and screened for AHL-producing and degrading strains. Isolates (n=107) stimulated AHL-mediated purple pigment production in AHL reporter strains Chromobacterium violaceum CV026 and VIR07. Based on their 16S rRNA gene sequences, most of these AHL-producing isolates were assigned to the genus Aeromonas, and they were divided into six groups. Isolates (n=46) degraded N-decanoyl-L-homoserine lactone (C10-HSL) within 24 h. Based on their 16S rRNA gene sequences, the most dominant AHL-degrading isolates were assigned to the genus Acinetobacter and divided into six groups. Strains Ooi24, Omo91, and Uzu81, which showed higher C10-HSL-degrading activity, showed putative AHL-acylase activity. 相似文献
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Taro Kato Nobutaka Someya Tsukasa Ikeda 《Bioscience, biotechnology, and biochemistry》2013,77(4):673-680
Pseudomonas sp. StFLB209 was isolated from potato leaf as an N-acylhomoserine lactone (AHL)-producing bacterium and showed a close phylogenetic relationship with P. cichorii, a known plant pathogen. Although there are no reports of potato disease caused by pseudomonads in Japan, StFLB209 was pathogenic to potato leaf. In this study, we reveal the complete genome sequence of StFLB209, and show that the strain possesses a ppuI-rsaL-ppuR quorum-sensing system, the sequence of which shares a high similarity with that of Pseudomonas putida. Disruption of ppuI results in a loss of AHL production as well as remarkable reduction in motility. StFLB209 possesses strong pectate lyase activity and causes maceration on potato tuber and leaf, which was slightly reduced in the ppuI mutant. These results suggest that the quorum-sensing system is well conserved between StFLB209 and P. putida and that the system is essential for motility, full pectate lyase activity, and virulence in StFLB209. 相似文献
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竹节状甲烷鬃菌(Methanosaeta harundinacea)6Ac是本实验室分离自厌氧颗粒污泥中的甲烷古菌新种。该菌具有短杆(3μm-5μm)和长链状(>200μm)两种细胞形态,且与细胞密度相关,暗示该菌可能存在群感效应调控的细胞形态变化。【目的】验证该菌存在群感效应信号分子并与细胞形态变化相关。【方法】用高丝氨酸内酯指示菌Agrobacterium tumefaciens NTL4检测菌株6Ac的培养液,并用购买的高丝氨酸内酯标准品加入短杆菌株6Ac检测形态变化。【结果】菌株6Ac的培养液中含有高丝氨酸内酯类物质。实验证明化学合成的高丝氨酸内酯N-(β-酮基)辛酰高丝氨酸内酯能够促进竹节状甲烷鬃菌的长链细胞形成。而且在马氏甲烷八叠球菌(Methanosarcina mazei)、热自养甲烷杆菌(Methanothermobacter thermautotrophicus)和甲酸甲烷杆菌(Methanobacterium formicicum)的培养液中也检测到了高丝氨酸内酯。【结论】多种甲烷古菌可以产生高丝氨酸内酯类物质,并可能以此类物质作为群感效应的信号分子。 相似文献
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K. Saipriya C.H. Swathi K.S. Ratnakar V. Sritharan 《Journal of applied microbiology》2020,128(1):15-27
Acinetobacter baumannii causes several nosocomial infections and poses major threat when it is multidrug resistant. Even pan drug-resistant strains have been reported in some countries. The intensive care unit (ICU) mortality rate ranged from 45.6% to 60.9% and it is as high as 84.3% when ventilator-associated pneumonia was caused by XDR (extensively drug resistant) A. baumannii. Acinetobacter baumannii constituted 9.4% of all Gram-negative organisms throughout the hospital and 22.6% in the ICUs according to a study carried out in an Indian hospital. One of the major factors contributing to drug resistance in A. baumannii infections is biofilm development. Quorum sensing (QS) facilitates biofilm formation and therefore the search for ‘quorum quenchers’ has increased recently. Such compounds are expected to inhibit biofilm formation and hence reduce/prevent development of drug resistance in the bacteria. Some of these compounds also target synthesis of some virulence factors (VF). Several candidate drugs have been identified and are at various stages of drug development. Since quorum quenching, inhibition of biofilm formation and inhibition of VF synthesis do not pose any threat to the DNA replication and cell division of the bacteria, chances of resistance development to such compounds is presumably rare. Thus, these compounds ideally qualify as adjunct therapeutics and could be administered along with an antibiotic to reduce chances of resistance development and also to increase the effectiveness of antimicrobial therapy. This review describes the state-of-art in QS process in Gram-negative bacteria in general and in A. baumannii in particular. This article elaborates the nature of QS mediators, their characteristics, and the methods for their detection and quantification. Various potential sites in the QS pathway have been highlighted as drug targets and the candidate quorum quenchers which inhibit the mediator’s synthesis or function are enlisted. 相似文献
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革兰氏阴性菌根据信号分子N-酰基高丝氨酸内酯(AHLs)的浓度可以监测周围环境中自身或其他细菌的数量变化,当信号分子达到一定浓度阈值时,能启动相关基因的表达来适应环境的变化,这一调控系统被称为细菌的群体感应(quorumsensing,QS)系统。快速简便而有效地检测细菌是否以及产生何种信号分子成为深入研究和了解细菌群体感应的重要手段。现对信号分子AHLs敏感的用于检测不同的信号分子AHLs的微生物传感菌进行综述,并对其检测能力进行了讨论。 相似文献
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十二烷酰-l-高丝氨酸内酯(N-dodecanoyl-l-homoserine lactone, C12-HSL)是介导细菌群感效应的信号分子,调控细菌群体行为。本研究旨在探究C12-HSL对肠道微生物分离培养的影响,丰富小鼠肠道微生物可培养菌株资源的种类和数量。利用添加C12-HSL的培养基对小鼠肠道内容物进行菌株分离培养,共获得235个分离株,通过16S rRNA基因初步鉴定出54种菌,其中包含1个潜在新科,4个潜在新属,4个潜在新种;与实验室前期建立的小鼠肠道微生物菌株资源库mGMB比较,42个菌种为本研究的新增物种,丰富了菌库的物种多样性;统计分析发现,通过该方法分离获得的革兰氏阴性菌,特别是变形菌门的比例,显著高于未添加C12-HSL的普通分离培养方法。随后,对发现的一个新菌种进行培养实验表明,外源C12-HSL在20–200μmol/L浓度范围内对该菌种生长具有显著促进作用,而高浓度的C12-HSL则显著抑制该菌细胞密度。本研究证实了细菌群感效应分子在特定浓度范围内有助于肠道中革兰氏阴性菌的生长、分离和培养。尽管群感效应信号分子C12-HSL促进肠道菌株生长的机制还有待进一步探究,但本研究的发现为利用细菌群感效应信号分子靶向分离培养和调控肠道菌群提供了新思路。 相似文献
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Gram-negative bacteria most often use N-acyl homoserine lactones (AHLs) as intercellular quorum-sensing signal molecules. In this study, it was demonstrated that rice plants contain AHL mimic molecules that are very sensitive to the highly specific AiiA lactonase enzyme and can activate three different AHL bacterial biosensors, indicating that the compounds have a homoserine lactone structure and could be AHLs. The possible source and biological significance of this finding are discussed. 相似文献
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Rafael Jorge León Morcillo Juan A. Ocampo José M. García Garrido 《Plant signaling & behavior》2012,7(12):1584-1588
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Rasch M Rasmussen TB Andersen JB Persson T Nielsen J Givskov M Gram L 《Journal of applied microbiology》2007,102(3):826-837
AIM: To investigate the potential of quorum sensing inhibitors (QSI) as food preservative agents in a food product, where bacterial spoilage is controlled by quorum sensing (QS). METHODS AND RESULTS: The effects of well-known QSI were tested on spoilage phenotypes and on QS-regulated genes of a bean sprout spoiling bacterial isolate (Pectobacterium A2JM) in laboratory substrates and in a bean sprout model system. The acylated homoserine lactones (AHL) analogues PenS-AHL and HepS-AHL decreased the specific protease activity of Pectobacterium A2JM in broth but did not reduce the expression of a QS-regulated secretion protein, and were without effect on soft rot of bean sprouts. The QSI ProS-AHL, furanone C-30, patulin, penicillic acid and 4-nitropyridine-N-oxide did not have any effect on protease activity, on gene expression or bean sprout appearance at nongrowth inhibitory concentrations. Extracts from garlic and bean sprouts induced the QS system of Pectobacterium in bean sprouts and a broth system, respectively. CONCLUSIONS: Among the several well-known QSI compounds, only PenS-AHL and HepS-AHL, inhibited QS-regulated protease activity of Pectobacterium A2JM in broth cultures, but had no effect on bean sprout spoilage. SIGNIFICANCE AND IMPACT OF THE STUDY: The QSI compounds must be selected in the specific system in which they are to function and they cannot easily be transferred from one QS system to another. 相似文献
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J. F. Y. Brookfield 《Evolution; international journal of organic evolution》1998,52(5):1263-1269
Bacteria respond to cell density by expressing genes whose products are beneficial to the population as a whole. This response is brought about through the release into the medium of signaling molecules of the class N-acyl homoserine lactones, the concentration of which determines the level of gene expression. This form of communication between cells has been termed “quorum sensing,” and has been found to operate in the control of many functions in a variety of gram-negative bacteria. As with all signaling between individuals, if fitness costs are associated with the release of and response to the signal, the inclusive fitness of alleles responsible for the phenomenon depends upon genetic relatedness between signaler and responder. The situation is considered in explicit models for bacterial population genetics, in which the critical parameter determining the success of quorum sensing is the mean number of cells founding a population sharing a patch of resource. It is found that extensive polymorphism for the presence or absence of quorum sensing is expected for a wide range of parameter space. If local communities of bacteria contain diverse species, community stability may be the consequence of these interactions rather than polymorphism. 相似文献
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Kastbjerg VG Nielsen KF Dalsgaard I Rasch M Bruhn JB Givskov M Gram L 《Journal of applied microbiology》2007,102(2):363-374
AIMS: To profile the quorum-sensing (QS) signals in Yersinia ruckeri and to examine the possible regulatory link between QS signals and a typical QS-regulated virulence phenotype, a protease. METHODS AND RESULTS: Liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) showed that Y. ruckeri produced at least eight different acylated homoserine lactones (AHLs) with N-(3-oxooctanoyl)-L-homoserine lactone (3-oxo-C8-HSL) being the dominant molecule. Also, some uncommon AHL, N-(3-oxoheptanoyl)-L-homoserine lactone (3-oxo-C7-HSL) and N-(3-oxononanoyl)-L-homoserine lactone (3-oxo-C9-HSL), were produced. 3-oxo-C8-HSL was detected in organs from fish infected with Y. ruckeri. Protease production was significantly lower at temperatures above 23 degrees C than below although growth was faster at the higher temperatures. Neither addition of sterile filtered high-density Y. ruckeri culture supernatant nor the addition of pure exogenous AHLs induced protease production. Furthermore, three QS inhibitors (QSIs), sulfur-containing AHL analogues, did not inhibit protease production in Y. ruckeri. CONCLUSIONS: Exogenous AHL or sulfur-containing AHL analogues did not influence the protease production indicating that protease production may not be QS regulated in Y. ruckeri. SIGNIFICANCE AND IMPACT OF THE STUDY: The array of different AHLs produced indicates that the QS system of Y. ruckeri is complex and could involve several regulatory systems. In this case, neither AHLs nor QSI would be likely to directly affect a QS-regulated phenotype. 相似文献
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Bruno Aquino James M. Bradley Shelley Lumba 《The Plant journal : for cell and molecular biology》2021,105(2):322-334
A collection of small molecules called strigolactones (SLs) act as both endogenous hormones to control plant development and as ecological communication cues between organisms. SL signalling overlaps with that of a class of smoke-derived compounds, karrikins (KARs), which have distinct yet overlapping developmental effects on plants. Although the roles of SLs in shoot and root development, in the promotion of arbuscular mycorrhizal (AM) fungal branching and in parasitic plant germination have been well characterized, recent data have illustrated broader roles for these compounds in the rhizosphere. Here, we review the known roles of SLs in development, growth of AM fungi and germination of parasitic plants to develop a framework for understanding the use of SLs as molecules of communication in the rhizosphere. It appears, for example, that there are many connections between SLs and phosphate utilization. Low phosphate levels regulate SL metabolism and, in turn, SLs sculpt root and shoot architecture to coordinate growth and optimize phosphate uptake from the environment. Plant-exuded SLs attract fungal symbionts to deliver inorganic phosphate (Pi) to the host. These and other examples suggest the boundary between exogenous and endogenous SL functions can be easily blurred and a more holistic view of these small molecules is likely to be required to fully understand SL biology. Related to this, we summarize and discuss evidence for a primitive role of SLs in moss as a quorum sensing-like molecule, providing a unifying concept of SLs as endogenous and exogenous signalling molecules. 相似文献
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群体感应(Quorum sensing,QS)是细菌在进化过程中形成的依赖于群体密度的细菌间交流方式。许多革兰氏阴性细菌以N-酰基高丝氨酸内酯(AHL)为信号分子,感应自身群体密度并调控致病基因表达。因此,淬灭AHLs信号分子可防治此类细菌引起的植物病害。本实验室前期已筛选得到了一株具有AHLs信号降解能力的不动杆菌菌株Acinetobacter sp.77,本研究通过基因组文库筛选,自菌株77中克隆得到具有AHLs降解活性的基因aidE。该基因编码268个氨基酸。序列一致性比较发现aidE的氨基酸序列与吉伦伯不动杆菌Acinetobacter gyllenbergii CIP110306中β-内酰胺酶一致性高达95%,但与已知的AHLs降解酶序列一致性较低,最高为缓黄分支杆菌Mycobacterium lentiflavum中AHL内酯酶Att M/Aii B家族蛋白(CQD23908.1),一致性仅为33%。通过高压液相色谱(HPLC)分析Aid E蛋白处理N-己酰基高丝氨酸内酯(C6-HSL)的反应产物,证明aidE为AHL内酯酶。序列比对研究发现,aidE基因在不动杆菌属中并不保守,其在菌株77基因组中的上下游的基因排列存在菌株水平的特异性,且aidE基因下游存在疑似IS插入序列,上述证据表明aidE基因有可能是通过水平转移进入Acinetobacter sp.77基因组中,或其在基因组中的位置发生过重排。表达aidE的软腐果胶杆菌Z3-3中完全检测不到AHLs信号产生,且致病力明显降低。综上所述,aidE为新发现的AHL内酯酶。在防治依赖QS系统表达致病性的细菌病害中具有应用潜力。 相似文献