scholarly journals Quorum Sensing Bacteria in the Phycosphere of HAB Microalgae and Their Ecological Functions Related to Cross-Kingdom Interactions

2021 ◽  
Vol 19 (1) ◽  
pp. 163
Author(s):  
Yanchao Zhang ◽  
Li Zheng ◽  
Shuai Wang ◽  
Yangguo Zhao ◽  
Xiyuan Xu ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Film Formation ◽  
Homoserine Lactone ◽  
Rrna Gene ◽  
16S Rrna Gene Analysis ◽  
Signalling Molecules ◽  
Film Forming ◽  
Layer Chromatography

It has been proven that the relationship between microalgae and bacteria affects the dynamic process of harmful algal blooms (HABs). Microalgae-associated microorganisms widely exist in the phycosphere and play an essential role in algae-bacteria cross-kingdom interactions. Among these processes, quorum sensing (QS), as a communication system of bacteria, is thought to participate in algae-bacteria interactions. However, the species of QS bacteria in the phycosphere and their ecological function are still unknown. In this study, microalgae-associated microorganisms with a QS system were screened by the biosensor method and identified based on 16S rRNA gene analysis. The types and number of acyl-L-homoserine lactone (AHL) signalling molecules produced by QS bacteria were analysed by thin layer chromatography (TLC) bioautography and gas chromatography-mass spectrometer (GC-MS). The film formation, β-dimethylmercaptopropionic (DMSP) degradation and algae growth effects of QS bacteria were investigated. The results showed that 113 QS bacteria were isolated from 842 microalgae-associated bacteria. Detection of AHL molecules in 10 different species of QS bacteria showed that most of them were N-(3-Oxodecanoyl)-L-homoserine lactone (OC10-HSL), N-Octanoyl-L-homoserine lactone (C8-HSL) and N-(3-Oxooctanoyl)-L-homoserine lactone (OC8-HSL). All 10 QS bacteria had film-forming ability, and they could degrade DMSP (except strain E26). The crude metabolic extracts of the 10 QS bacteria can inhibit or promote microalgae growth to different degrees. Our study is helpful to understand the role of microalgae-associated microorganisms with the QS system in algae-bacteria interactions and community succession of HAB microalgae.

Production of quorum-sensing-related signal molecules by epiphytic bacteria inhabiting wheat heads

2006 ◽  
Vol 52 (5) ◽  
pp. 411-418 ◽  
Author(s):  
Shigenobu Yoshida ◽  
Linda L Kinkel ◽  
Hirosuke Shinohara ◽  
Nobutaka Numajiri ◽  
Syuntaro Hiradate ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Population Size ◽  
Signal Molecules ◽  
Rrna Gene ◽  
Culturable Bacteria ◽  
Bacterial Isolates ◽  
16S Rrna Gene Sequences ◽  
Pantoea Ananatis ◽  
Signal Molecule ◽  
Layer Chromatography

The production of quorum-sensing-related signal molecules (QSRMs) among culturable bacteria comprising the community on wheat heads was investigated. The taxonomic position of 186 bacterial isolates obtained from ten heads was inferred based on 16S rRNA gene sequences, and their QSRM production was determined using two bioreporter strains of N-acylhomoserine lactones. Approximately 33% of isolates produced QSRMs, though the proportion of QSRM-producing isolates on a wheat head was significantly negatively correlated with population size. Most of the producing isolates were Pantoea species, most commonly Pantoea ananatis. Furthermore, the proportion of Pantoea ananatis that produced QSRMs was significantly negatively correlated with the number of bacterial genera (community richness) on each head. Finally, community richness was positively correlated with population size. Qualitative analysis using thin-layer-chromatography revealed that the QSRMs of Pantoea isolates were composed of at least two compounds. This is the first report indicating that Pantoea ananatis isolates inhabiting wheat heads are capable of producing QSRMs. QSRM production by Pantoea spp. may contribute to the predominance of this genus on wheat heads, particularly at relatively low population densities and community diversity.Key words: quorum sensing, signal molecule, epiphyte, wheat head, Pantoea spp.

scholarly journals N-Acyl homoserine lactone-mediated quorum sensing in pathogenic Aeromonas veronii biovar sobria strain 159: Identification of LuxIR homologs

2015 ◽  
Author(s):  
Xin Yue Chan ◽  
Kah Yan How ◽  
Wai Fong Yin ◽  
Kok Gan Chan
Keyword(s):  
Quorum Sensing ◽  
Bacterial Population ◽  
Gene Annotation ◽  
Homoserine Lactone ◽  
Genome Comparison ◽  
Acyl Homoserine Lactone ◽  
Gram Negative Bacteria ◽  
Signalling Molecules ◽  
Aeromonas Veronii ◽  
High Degree

Quorum sensing (QS) is a mechanism that plays important roles in gene expression in response to an expanding bacterial population. In many Gram-negative bacteria, N-acyl homoserine lactone is mainly secreted as the diffusible signalling molecules. This QS system has been shown to control diverse array of virulence and secondary metabolism. Recently, whole genome sequencing of Aeromonas veronii biovar sobria strain 159 was performed. Genome comparison with closely-related Aeromonas species showed that A. veronii strain 159 shares a high degree of genome synteny with A. hydrophila ATCC 7966. A detailed genome analysis and gene annotation led us to the findings that A. veronii strain 159 harbors QS system which relies on its signal generator, AveI and the transcriptional regulator, AveR. This Aeromonas strain was found to secrete N-butanoylacyl homoserine lactone (C4-HSL). Its LuxIR homologs are similar to proteins of LuxIR famililies among Aeromonas species. This study aims to gain further insights into AveIR system and to compare with AhyIR from A. hydrophila ATCC 7966 and AsaIR from A. salmonicida.

scholarly journals Algicidal Activity of Novel Indigenous Bacterial Strain, Paracoccus Sp., Against Harmful Algal Bloom Species, Karenia Mikimotoi

2021 ◽  
Author(s):  
Ning Ding ◽  
Wenjun Du ◽  
Yanlou Feng ◽  
Yuhao Song ◽  
Chao Wang ◽  
...  
Keyword(s):  
Bacterial Strain ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Harmful Algal Bloom ◽  
Growth Conditions ◽  
Inhibitory Effect ◽  
Algicidal Bacteria ◽  
Rrna Gene ◽  
Negative Effects ◽  
Karenia Mikimotoi

Abstract Harmful algal blooms have deleterious effects on aquatic ecosystems and human health. The application of algicidal bacteria is a promising and environmentally friendly method of preventing and eradicating harmful algal blooms. In this study, a screen for algicidal agents against harmful algal blooms was used to identify an algicidal bacterial strain isolated from a Karenia mikimotoi culture. Strain O-1 exhibited a strong inhibitory effect on harmful K. mikimotoi and was identified as a Paracoccus species via 16S rRNA gene sequence analysis. This strain killed K. mikimotoi by secreting active algicidal compounds, which were stable at temperatures of -80–121 °C, but these substances were sensitive to strongly acidic conditions. The algicidal properties of strain O-1 against K. mikimotoi were cell density- and time-dependent. No significant changes or negative effects were noted for two other Chlorophyta species, which highlighted the specificity of the studied algicidal substance. Finally, single-factor experiments revealed the optimum growth conditions of strain O-1 under different pH and temperature conditions. Strain O-1 therefore has potential as a bio-agent for reducing the biomass of harmful K. mikimotoi blooms.

scholarly journals Engineering quorum quenching enzymes: progress and perspectives

2019 ◽  
Vol 47 (3) ◽  
pp. 793-800 ◽  
Author(s):  
Shereen A. Murugayah ◽  
Monica L. Gerth
Keyword(s):  
Quorum Sensing ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Microbial Pathogens ◽  
Human Pathogens ◽  
New Approach ◽  
Signalling Molecules ◽  
The Stability

Abstract Quorum sensing is a key contributor to the virulence of many important plant, animal and human pathogens. The disruption of this signalling—a process referred to as ‘quorum quenching’—is a promising new approach for controlling microbial pathogens. In this mini-review, we have focused on efforts to engineer enzymes that disrupt quorum sensing by inactivating acyl-homoserine lactone signalling molecules. We review different approaches for protein engineering and provide examples of how these engineering approaches have been used to tailor the stability, specificity and activities of quorum quenching enzymes. Finally, we grapple with some of the issues around these approaches—including the disconnect between in vitro biochemistry and potential in vivo applications.

scholarly journals Effect of the luxI/R gene on AHL-signaling molecules and QS regulatory mechanism in Hafnia alvei H4

AMB Express ◽  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xue Li ◽  
Gongliang Zhang ◽  
Yaolei Zhu ◽  
Jingran Bi ◽  
Hongshun Hao ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Sea Cucumber ◽  
Draft Genome ◽  
Homoserine Lactone ◽  
Single Chromosome ◽  
Hafnia Alvei ◽  
Double Deletion ◽  
Genetic Level ◽  
Layer Chromatography ◽  
Positive Effect

AbstractHafnia alvei H4 is a bacterium subject to regulation by a N-acyl-l-homoserine lactone (AHL)-mediated quorum sensing system and is closely related to the corruption of instant sea cucumber. Studying the effect of Hafnia alvei H4 quorum sensing regulatory genes on AHLs is necessary for the quality and preservation of instant sea cucumber. In this study, the draft genome of H. alvei H4, which comprises a single chromosome of 4,687,151 bp, was sequenced and analyzed and the types of AHLs were analyzed employing thin-layer chromatography (TLC) and high resolution triple quadrupole liquid chromatography/mass spectrometry (LC/MS). Then the wild-type strain of H. alvei H4 and the luxI/R double mutant (ΔluxIR) were compared by transcriptome sequencing (RNA-seq). The results indicate that the incomplete genome sequence revealed the presence of one quorum-sensing (QS) gene set, designated as lasI/expR. Three major AHLs, N-hexanoyl-l-homoserine lactone (C6-HSL), N-butyryl-l-homoserine lactone (C4-HSL), and N-(3-oxo-octanoyl)-l-homoserine lactone (3-oxo-C8-HSL) were found, with C6-HSL being the most abundant. C6-HSL was not detected in the culture of the luxI mutant (ΔluxI) and higher levels of C4-HSL was found in the culture of the luxR mutant (ΔluxR), which suggested that the luxR gene may have a positive effect on C4-HSL production. It was also found that AHL and QS genes are closely related in the absence of luxIR double deletion. The results of this study can further elucidate at the genetic level that luxI and luxR genes are involved in the regulation of AHL.

scholarly journals Streptomycin Inhibits Quorum Sensing in Acinetobacter baumannii

2013 ◽  
Vol 57 (4) ◽  
pp. 1926-1929 ◽  
Author(s):  
Sunil D. Saroj ◽  
Philip N. Rather
Keyword(s):  
Quorum Sensing ◽  
Thin Layer ◽  
Acinetobacter Baumannii ◽  
Direct Analysis ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Content Type ◽  
Signal Production ◽  
Subinhibitory Concentrations ◽  
Layer Chromatography

ABSTRACTStreptomycin at subinhibitory concentrations was found to inhibit quorum sensing inAcinetobacter baumannii. Conditioned medium prepared by growth ofA. baumanniiin the presence of subinhibitory concentrations of streptomycin exhibited reduced activation of two quorum-sensing-regulated genes,abaI, encoding an autoinducer synthase, and A1S_0112. The reduced expression of AbaI resulted in greatly decreased levels of 3-OH-C12-HSL as confirmed by direct analysis using thin-layer chromatography. The effect on acyl-homoserine lactone (AHL) signal production was specific to streptomycin, as gentamicin and myomycin had no significant effect at subinhibitory levels.

scholarly journals Quorum sensing in Aliivibrio wodanis 06/09/139 and its role in controlling various phenotypic traits

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11980
Author(s):  
Amudha Deepalakshmi Maharajan ◽  
Hilde Hansen ◽  
Miriam Khider ◽  
Nils Peder Willassen
Keyword(s):  
Quorum Sensing ◽  
Protease Activity ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Phenotypic Traits ◽  
Signalling Molecules ◽  
A Cell ◽  
Cell Densities ◽  
Cell Culture Assay ◽  
Cytopathogenic Effect

Background Quorum Sensing (QS) is a cell-to-cell communication system that bacteria utilize to adapt to the external environment by synthesizing and responding to signalling molecules called autoinducers. The psychrotrophic bacterium Aliivibrio wodanis 06/09/139, originally isolated from a winter ulcer of a reared Atlantic salmon, produces the autoinducer N-3-hydroxy-decanoyl-homoserine-lactone (3OHC10-HSL) and encodes the QS systems AinS/R and LuxS/PQ, and the master regulator LitR. However, the role of QS in this bacterium has not been investigated yet. Results In the present work we show that 3OHC10-HSL production is cell density and temperature-dependent in A. wodanis 06/09/139 with the highest production occurring at a low temperature (6 °C). Gene inactivation demonstrates that AinS is responsible for 3OHC10-HSL production and positively regulated by LitR. Inactivation of ainS and litR further show that QS is involved in the regulation of growth, motility, hemolysis, protease activity and siderophore production. Of these QS regulated activities, only the protease activity was found to be independent of LitR. Lastly, supernatants harvested from the wild type and the ΔainS and ΔlitR mutants at high cell densities show that inactivation of QS leads to a decreased cytopathogenic effect (CPE) in a cell culture assay, and strongest attenuation of the CPE was observed with supernatants harvested from the ΔlitR mutant. Conclusion A. wodanis 06/09/139 use QS to regulate a number of activities that may prove important for host colonization or interactions. The temperature of 6 °C that is in the temperature range at which winter ulcer occurs, plays a role in AHL production and development of CPE on a Chinook Salmon Embryo (CHSE) cell line.

scholarly journals MARINE Streptomyces SP. UKMCC_PT15 PRODUCING UNDECYLPRODIGIOSIN WITH ALGICIDAL ACTIVITY

2016 ◽  
Vol 78 (11-2) ◽  
Author(s):  
Zaima Azira Zainal Abidin ◽  
Asmat Ahmad ◽  
Jalifah Latip ◽  
Gires Usup
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Biological Activities ◽  
Carbon Sources ◽  
Antibacterial Activities ◽  
Tolerance Test ◽  
Algicidal Activity ◽  
Rrna Gene ◽  
Streptomyces Sp ◽  
Marine Streptomyces

Marine actinomycetes are now in demand as they are capable of producing unique and novel compounds with wide biological activities. Marine Streptomyces sp. UKMCC_PT15  previously isolated from seawater collected in Pulau Tinggi, Johor was used in this study. Molecular identification showed high similarity of Streptomyces sp. UKMCC_PT15 with Streptomyces fradiae and S. diastaticus subsp. ardesiacus based on partial sequence of 16S rRNA gene. Further characterisations of this bacterium include spore morphology using SEM, growth on various media, salt tolerance test and carbon utilisation profile. This bacterium had straight spore chain with smooth-surfaced spores and was able to tolerate up to 11% NaCl with capabilities of utilising >40 carbon sources.  Undecylprodigiosin (C25H35N3O) was successfully purified through succession of column chromatography and finally using HPLC. Structure elucidation was confirmed through NMR spectroscopy, MS and comparison with established data. This compound demonstrated strong antibacterial activities against S. aureus, B. subtilis and C. albicans but weak antibacterial activities against E. coli, P. aeruginosa and Methicillin-resistant S. aureus (MRSA), Interestingly, undecylprodigiosin also demonstrated algicidal activity when tested against toxic dinoflagellates, A. minutum and P. bahamense, both of which are responsible for harmful algal blooms (HABs). Undecylprodiogiosin with concentration of 10-100 μg/ml gave ~100% algicidal activity against both dinoflagellates. Further testing with undecylprodigiosin concentration < 10 µg/ml showed that undecylprodigision was capable of killing significantly high numbers of both dinoflagellates, giving a high algicidal activity. Findings from this study suggested the potential use of undecylprodigiosin as algicidal agent which could be used for the mitigation of HABs

scholarly journals Isolation of novel quorum-sensing active bacteria from microbial mats in Shark Bay Australia

2019 ◽  
Vol 95 (4) ◽  
Author(s):  
James C Charlesworth ◽  
Cara Watters ◽  
Hon Lun Wong ◽  
Pieter T Visscher ◽  
Brendan P Burns
Keyword(s):  
Quorum Sensing ◽  
Microbial Mats ◽  
Signal Molecules ◽  
E Coli ◽  
Signalling Molecules ◽  
Shark Bay ◽  
Sensing Systems ◽  
Complex Phenotypes ◽  
Layer Chromatography ◽  
Tlc Separation

ABSTRACT Quorum sensing is a potent system of genetic control allowing phenotypes to be coordinated across localized communities. In this study, quorum sensing systems in Shark Bay microbial mats were delineated using a targeted approach analyzing whole mat extractions as well as the creation of an isolate library. A library of 165 isolates from different mat types were screened using the AHL biosensor E. coli MT102. Based on sequence identity 30 unique isolates belonging to Proteobacteria, Actinobacteria and Firmicutes were found to activate the AHL biosensor, suggesting AHLs or analogous compounds were potentially present. Several of the isolates have not been shown previously to produce signal molecules, particularly the members of the Actinobacteria and Firmicutes phyla including Virgibacillus, Halobacillius, Microbacterium and Brevibacterium. These active isolates were further screened using thin-layer chromatography (TLC) providing putative identities of AHL molecules present within the mat communities. Nine isolates were capable of producing several spots of varying sizes after TLC separation, suggesting the presence of multiple signalling molecules. This study is the first to delineate AHL-based signalling in the microbial mats of Shark Bay, and suggests quorum sensing may play a role in the ecosphysiological coordination of complex phenotypes across microbial mat communities.

scholarly journals Utilization of Acyl-Homoserine Lactone Quorum Signals for Growth by a Soil Pseudomonad and Pseudomonas aeruginosa PAO1

2003 ◽  
Vol 69 (10) ◽  
pp. 5941-5949 ◽  
Author(s):  
Jean J. Huang ◽  
Jong-In Han ◽  
Lian-Hui Zhang ◽  
Jared R. Leadbetter
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Atmospheric Pressure Chemical Ionization ◽  
Homoserine Lactone ◽  
Small Subunit ◽  
Rrna Gene ◽  
Ionization Mass ◽  
Small Subunit Rrna ◽  
Strain Pao1 ◽  
Pressure Chemical Ionization

ABSTRACT Acyl-homoserine lactones (AHLs) are employed by several Proteobacteria as quorum-sensing signals. Past studies have established that these compounds are subject to biochemical decay and can be used as growth nutrients. Here we describe the isolation of a soil bacterium, Pseudomonas strain PAI-A, that degrades 3-oxododecanoyl-homoserine lactone (3OC12HSL) and other long-acyl, but not short-acyl, AHLs as sole energy sources for growth. The small-subunit rRNA gene from strain PAI-A was 98.4% identical to that of Pseudomonas aeruginosa, but the soil isolate did not produce obvious pigments or AHLs or grow under denitrifying conditions or at 42°C. The quorum-sensing bacterium P. aeruginosa, which produces both 3OC12HSL and C4HSL, was examined for the ability to utilize AHLs for growth. It did so with a specificity similar to that of strain PAI-A, i.e., degrading long-acyl but not short-acyl AHLs. In contrast to the growth observed with strain PAI-A, P. aeruginosa strain PAO1 growth on AHLs commenced only after extremely long lag phases. Liquid-chromatography-atmospheric pressure chemical ionization-mass spectrometry analyses indicate that strain PAO1 degrades long-acyl AHLs via an AHL acylase and a homoserine-generating HSL lactonase. A P. aeruginosa gene, pvdQ (PA2385), has previously been identified as being a homologue of the AHL acylase described as occurring in a Ralstonia species. Escherichia coli expressing pvdQ catalyzed the rapid inactivation of long-acyl AHLs and the release of HSL. P. aeruginosa engineered to constitutively express pvdQ did not accumulate its 3OC12HSL quorum signal when grown in rich media. However, pvdQ knockout mutants of P. aeruginosa were still able to grow by utilizing 3OC12HSL. To our knowledge, this is the first report of the degradation of AHLs by pseudomonads or other γ-Proteobacteria, of AHL acylase activity in a quorum-sensing bacterium, of HSL lactonase activity in any bacterium, and of AHL degradation with specificity only towards AHLs with long side chains.

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