5 reference(s) found. Listing paper details in reverse chronological order. We are grateful to Keith Bradnam for improvment of this script
Title: Specific quorum sensing molecules of ammonia oxidizers and their role during ammonium metabolism in Zhalong wetland, China Liu F, Zhang Y, Liang H, Gao D Ref: Sci Total Environ, 666:1106, 2019 : PubMed
The primary challenge of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) surviving in wetlands are the rapid and unpredictable environmental changes. To adapt to a fluctuant environment, ammonia oxidizers have to communicate with each other via acyl-homoserine lactones (AHLs). In this study, AOA and AOB in the soil samples taken from Zhalong wetland were incubated. Dynamics of AHLs during the incubation of ammonia oxidizers were measured. Then, the specific AHLs of AOA and AOB were identified, respectively. The results showed that AOA secreted N-butyryl-dl-homoserine lactone (C4-HSL) and N-octanoyl-l-homoserine lactone (C8-HSL) to cope with nitrite accumulation, while they secreted N-(3-oxododecanoyl)-dl-homoserine lactone (OXOC12-HSL) to regulate their ammonium metabolism activity. AOB secreted N-hexanoyl-dl-homoserine lactone (C6-HSL), N-dodecanoyl-l-homoserine lactone (C12-HSL), N-tetradecanoyl-dl-homoserine lactone (C14-HSL) and N-(3-oxododecanoyl)-tetradecanoyl-dl-homoserine lactone (OXOC14-HSL) only to enhance the metabolism activity. The dominant AOA belonged to the Nitrososphaera lineage, while the dominant AOB grouped into the Nitrosomonas lineage. The AHLs receptor homologs were identified in both AOA and AOB, which confirmed that AOA and AOB had the QS system. The present work was the first study that elucidated the QS system of AOA and AOB in multidimensional, and confirmed the role of QS system in ammonia oxidizers' metabolism.
        
Title: Production of N-acyl homoserine lactones by Chromobacterium haemolyticum KM2 isolated from the river water in Malaysia Priya K, Sulaiman J, How KY, Yin WF, Chan KG Ref: Arch Microbiol, 200:1135, 2018 : PubMed
Quorum sensing (QS) is a term used to describe cell-to-cell communication that enables bacteria to orchestrate group behaviours according to density of bacterial cells. In Gram-negative bacteria, this signalling system is widely known to regulate a variety of different phenotypes such as antibiotic production and biofilm formation. In this study, we report the production of N-acyl homoserine lactones produced by Chromobacterium haemolyticum strain KM2, a bacterium isolated from a river water of a reserved tropical national park. Preliminary screening of QS activity using biosensor reporter assays indicated that C. haemolyticum strain KM2 produces both short- and long-chain AHLs. Analysis with high-resolution liquid chromatography-mass spectrometry (LC-MS/MS) analysis revealed the production of three AHLs by strain KM2: N-octanoyl-L-homoserine lactone (C8-HSL), N-dodecanoyl-L-homoserine lactone (C12-HSL), and N-3-oxo-dodecanoyl-L-homoserine lactone (OC12-HSL). This bacterial isolate also exhibited strong beta-haemolytic activity. To the best of our knowledge, this is the first documentation of QS activity and multiple AHLs production by C. haemolyticum strain KM2.
        
Title: Unusual multiple production of N-acylhomoserine lactones a by Burkholderia sp. strain C10B isolated from dentine caries Goh SY, Tan WS, Khan SA, Chew HP, Abu Kasim NH, Yin WF, Chan KG Ref: Sensors (Basel), 14:8940, 2014 : PubMed
Bacteria realize the ability to communicate by production of quorum sensing (QS) molecules called autoinducers, which regulate the physiological activities in their ecological niches. The oral cavity could be a potential area for the presence of QS bacteria. In this study, we report the isolation of a QS bacterial isolate C10B from dentine caries. Preliminary screening using Chromobacterium violaceum CV026 biosensor showed that isolate C10B was able to produce N-acylhomoserine lactones (AHLs). This bacterium was further identified as a member of Burkholderia, an opportunistic pathogen. The isolated Burkholderia sp. was confirmed to produce N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL), N-decanoyl-L-homoserine lactone (C10-HSL) and N-dodecanoyl-L-homoserine lactone (C12-HSL).
        
Title: Characterization of quorum sensing and quorum quenching soil bacteria isolated from Malaysian tropical montane forest Chong TM, Koh CL, Sam CK, Choo YM, Yin WF, Chan KG Ref: Sensors (Basel), 12:4846, 2012 : PubMed
We report the production and degradation of quorum sensing N-acyl-homoserine lactones by bacteria isolated from Malaysian montane forest soil. Phylogenetic analysis indicated that these isolates clustered closely to the genera of Arthrobacter, Bacillus and Pseudomonas. Quorum quenching activity was detected in six isolates of these three genera by using a series of bioassays and rapid resolution liquid chromatography analysis. Biosensor screening and high resolution liquid chromatography-mass spectrometry analysis revealed the production of N-dodecanoyl-L-homoserine lactone (C12-HSL) by Pseudomonas frederiksbergensis (isolate BT9). In addition to degradation of a wide range of N-acyl-homoserine lactones, Arthrobacter and Pseudomonas spp. also degraded p-coumaroyl-homoserine lactone. To the best of our knowledge, this is the first documentation of Arthrobacter and Pseudomonas spp. capable of degrading p-coumaroyl-homoserine lactone and the production of C12-HSL by P. frederiksbergensis.
A great deal of research has been done to understand bacterial cell-to-cell signaling systems, but there is still a large gap in our current knowledge because the majority of microorganisms in natural environments do not have cultivated representatives. Metagenomics is one approach to identify novel quorum sensing (QS) systems from uncultured bacteria in environmental samples. In this study, fosmid metagenomic libraries were constructed from a forest soil and an activated sludge from a coke plant, and the target genes were detected using a green fluorescent protein (GFP)-based Escherichia coli biosensor strain whose fluorescence was screened by spectrophotometry. DNA sequence analysis revealed two pairs of new LuxI family N-acyl-L-homoserine lactone (AHL) synthases and LuxR family transcriptional regulators (clones N16 and N52, designated AubI/AubR and AusI/AusR, respectively). AubI and AusI each produced an identical AHL, N-dodecanoyl-L-homoserine lactone (C(12)-HSL), as determined by nuclear magnetic resonance (NMR) and mass spectrometry. Phylogenetic analysis based on amino acid sequences suggested that AusI/AusR was from an uncultured member of the Betaproteobacteria and AubI/AubR was very deeply branched from previously described LuxI/LuxR homologues in isolates of the Proteobacteria. The phylogenetic position of AubI/AubR indicates that they represent a QS system not acquired recently from the Proteobacteria by horizontal gene transfer but share a more ancient ancestry. We demonstrated that metagenomic screening is useful to provide further insight into the phylogenetic diversity of bacterial QS systems by describing two new LuxI/LuxR-type QS systems from uncultured bacteria.