Displaying publications 1 - 20 of 43 in total

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  1. 16-Hydroxycembra-1,3,7,11-tetraene, a new Cembrane Diterpene from Malaysian Soft Coral Genus Sarcophyton
    Kamada T, Phan CS, Tin HS, Vairappan CS, Muhammad TST
    Nat Prod Commun, 2016 Aug;11(8):1077-1078.
    PMID: 30725560
    One new cembrane diterpene, 16-hydroxycembra-1,3,7,11-tetraene (1), along with three known compounds, 15-hydroxycembra-1,3,7,11-tetraene (2), sarcophine (3) and sarcophytoxide (4) were isolated from Sarcophyton sp. collected from Karah Island, Terengganu, West Malaysia. Their structures were elucidated based on spectroscopic data. Activities of these compounds against antibacterial resistant clinical bacteria are reported. Only 1 exhibited inhibition against Staphylococcus aureus.
    Matched MeSH terms: 4-Butyrolactone
  2. A novel medium for the isolation of N-acylhomoserine lactone-degrading bacteria
    Chan KG, Yin WF, Sam CK, Koh CL
    J Ind Microbiol Biotechnol, 2009 Feb;36(2):247-51.
    PMID: 18946694 DOI: 10.1007/s10295-008-0491-x
    A novel chemically defined medium, named KG medium, supplemented with N-3-oxo-hexanoylhomoserine lactone (3-oxo-C6-HSL), an acylhomoserine lactone (AHL) used as signalling molecules in Gram-negative bacterial cell-to-cell communication, as the sole source of carbon and nitrogen, was designed and successfully used for the enrichment and isolation of AHL-degrading bacteria. A 3-oxo-C6-HSL-degrading bacterium, 13sw7, was isolated from sewage after six enrichment transfers in the 3-oxo-C6-HSL-containing KG medium. On the basis of the almost complete 16S ribosomal DNA sequence, isolate 13sw7 was clustered with unculturable beta-proteobacteria. This study indicates that the AHL-containing KG medium is effective in isolating AHL-degrading bacteria, including those previously considered unculturable, from environmental sources. To the best of our knowledge, this is the first documentation of the isolation of an AHL-degrading proteobacterium from sewage.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives*; 4-Butyrolactone/metabolism
  3. Fulltext AidP, a novel N-Acyl homoserine lactonase gene from Antarctic Planococcus sp
    See-Too WS, Ee R, Lim YL, Convey P, Pearce DA, Yin WF, et al.
    Sci Rep, 2017 02 22;7:42968.
    PMID: 28225085 DOI: 10.1038/srep42968
    Planococcus is a Gram-positive halotolerant bacterial genus in the phylum Firmicutes, commonly found in various habitats in Antarctica. Quorum quenching (QQ) is the disruption of bacterial cell-to-cell communication (known as quorum sensing), which has previously been described in mesophilic bacteria. This study demonstrated the QQ activity of a psychrotolerant strain, Planococcus versutus strain L10.15T, isolated from a soil sample obtained near an elephant seal wallow in Antarctica. Whole genome analysis of this bacterial strain revealed the presence of an N-acyl homoserine lactonase, an enzyme that hydrolyzes the ester bond of the homoserine lactone of N-acyl homoserine lactone (AHLs). Heterologous gene expression in E. coli confirmed its functions for hydrolysis of AHLs, and the gene was designated as aidP (autoinducer degrading gene from Planococcus sp.). The low temperature activity of this enzyme suggested that it is a novel and uncharacterized class of AHL lactonase. This study is the first report on QQ activity of bacteria isolated from the polar regions.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives; 4-Butyrolactone/analysis; 4-Butyrolactone/metabolism
  4. Biogenic larvicidal formulation of metabolites from Steinernema saimkayi symbiont Xenorhabdus stockiae KUT6 against dengue vector Aedes aegypti
    Jissin M, Vani C
    Trop Biomed, 2020 Sep 01;37(3):791-802.
    PMID: 33612792 DOI: 10.47665/tb.37.3.791
    To characterize the production and larvicidal activity of Xenorhabdus stockiae KUT6 Petroleum ether extracts from Luria Broth and induced Quorum sensing medium containing N-3- oxododecanoyl Homoserine Lactone inducer against dengue vector Aedes aegypti. The Galleria mellonella larvae were reared for the isolation of Steinernema saimkayi symbiont Xenorhabdus stockiae KUT6 from Cucumber field soil sample in NBTA. Then for the extraction of compounds the KUT6 strains were cultured in Luria Broth and Quorum Sensing optimized media using N-3-oxododecanoyl homoserine lactone inducer. The larvicidal activity of Xenorhabdus stockiae KUT6 of petroleum ether extracts were bioassayed against 4th instar Aedes aegypti dengue vector. The maximum rate of mortality were recorded of the samples A-24h, B-48h, C-72h, A1-24h, B1-48h, C1-72h at different concentrations 50 µg/ml, 100 µg/ml and 150 µg/ml respectively for 24h to 72h of exposure treatment. The morphological characteristics of Xenorhabdus stockiae KUT6 in NBTA were red core colonies with blue background surrounded by zone of inhibition. After 24h exposure maximum rate of 100% mortality of Aedes aegypti 4th instar larvae was attained when treated with sample C1-72h 50 µg/ml of the petroleum ether extracts of quorum sensed medium whereas the sample C 72h petroleum ether extracts of KUT6 cultured in Luria broth recorded 100% mortality at 150 µg on 24h exposure indicates enhancement in the product yield. The study assures the use of Xenorhabdus stockiae KUT6 petroleum ether extracts as biocontrol agent could be beneficial for the control of dengue vectors.
    Matched MeSH terms: 4-Butyrolactone
  5. Biosynthesis of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer by Cupriavidus sp. USMAA1020 isolated from Lake Kulim, Malaysia
    Amirul AA, Yahya AR, Sudesh K, Azizan MN, Majid MI
    Bioresour Technol, 2008 Jul;99(11):4903-9.
    PMID: 17981028
    Cupriavidus sp. USMAA1020 was isolated from Malaysian environment and able to synthesize poly(3-hydroxybutyrate-co-4-hydroxybutyrate), [P(3HB-co-4HB)] when grown on gamma-butyrolactone as the sole carbon source. The polyester was purified from freeze-dried cells and analyzed by nuclear magnetic resonance (NMR) spectroscopy. 1H and 13C NMR results confirmed the presence of 3HB and 4HB monomers. In a one-step cultivation process, P(3HB-co-4HB) accumulation by Cupriavidus sp. USMAA1020 was affected by carbon to nitrogen ratio (C/N). A two-step cultivation process accumulated P(3HB-co-4HB) copolyester with a higher 4HB fraction (53 mol%) in nitrogen-free mineral medium containing gamma-butyrolactone. The biosynthesis of P(3HB-co-4HB) was also achieved by using 4-hydroxybutyric acid and alkanediol as 1,4-butanediol. The composition of copolyesters varied from 32 to 51 mol% 4HB, depending on the carbon sources supplied. The copolyester produced by Cupriavidus sp. USMAA1020 has a random sequence distribution of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) units when analyzed by nuclear magnetic resonance (NMR) spectroscopy. When gamma-butyrolactone was used as the sole carbon source, the 4HB fraction in copolyester increased from 25 to 60 mol% as the concentration of gamma-butyrolactone in the culture medium increased from 2.5 g/L to 20.0 g/L.
    Matched MeSH terms: 4-Butyrolactone/pharmacology
  6. Characterization of quorum sensing genes and N-acyl homoserine lactones in Citrobacter amalonaticus strain YG6
    Kher HL, Krishnan T, Letchumanan V, Hong KW, How KY, Lee LH, et al.
    Gene, 2019 Feb 05;684:58-69.
    PMID: 30321658 DOI: 10.1016/j.gene.2018.10.031
    In the phylum of Proteobacteria, quorum sensing (QS) system is widely driven by synthesis and response of N-acyl homoserine lactone (AHL) signalling molecules. AHL is synthesized by LuxI homologue and sensed by LuxR homologue. Once the AHL concentration achieves a threshold level, it triggers the regulation of target genes. In this study, QS activity of Citrobacter amalonaticus strain YG6 which was isolated from clams was investigated. In order to characterise luxI/R homologues, the genome of C. amalonaticus strain YG6 (4.95 Mbp in size) was sequenced using Illumina MiSeq sequencer. Through in silico analysis, a pair of canonical luxI/R homologues and an orphan luxR homologue were identified and designated as camI, camR, and camR2, respectively. A putative lux box was identified at the upstream of camI. The camI gene was cloned and overexpressed in E. coli BL21 (DE3)pLysS. High-resolution triple quadrupole liquid chromatography mass spectrometry (LC-MS/MS) analysis verified that the CamI is a functional AHL synthase which produced multiple AHL species, namely N‑butyryl‑l‑homoserine lactone (C4-HSL), N‑hexanoyl‑l‑homoserine lactone (C6-HSL), N‑octanoyl‑l‑homoserine lactone (C8-HSL), N‑tetradecanoyl‑l‑homoserine lactone (C14-HSL) and N‑hexadecanoyl‑l‑homoserine lactone (C16-HSL) in C. amalonaticus strain YG6 and camI gene in recombinant E. coli BL21(DE3)pLysS. To our best knowledge, this is the first functional study report of camI as well as the first report describing the production of C14-HSL by C. amalonaticus.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives; 4-Butyrolactone/metabolism
  7. Fulltext Classification of different pineapple varieties grown in Malaysia based on volatile fingerprinting and sensory analysis
    Lasekan O, Hussein FK
    Chem Cent J, 2018 Dec 19;12(1):140.
    PMID: 30569201 DOI: 10.1186/s13065-018-0505-3
    BACKGROUND: Pineapple is highly relished for its attractive sweet flavour and it is widely consumed in both fresh and canned forms. Pineapple flavour is a blend of a number of volatile and non-volatile compounds that are present in small amounts and in complex mixtures. The aroma compounds composition may be used for purposes of quality control as well as for authentication and classification of pineapple varieties.

    RESULTS: The key volatile compounds and aroma profile of six pineapple varieties grown in Malaysia were investigated by gas chromatography-olfactometry (GC-O), gas-chromatography-mass spectrometry and qualitative descriptive sensory analysis. A total of 59 compounds were determined by GC-O and aroma extract dilution analysis. Among these compounds, methyl-2-methylbutanoate, methyl hexanoate, methyl-3-(methylthiol)-propanoate, methyl octanoate, 2,5-dimethyl-4-methoxy-3(2H)-furanone, δ-octalactone, 2-methoxy-4-vinyl phenol, and δ-undecalactone contributed greatly to the aroma quality of the pineapple varieties, due to their high flavour dilution factor. The aroma of the pineapples was described by seven sensory terms as sweet, floral, fruity, fresh, green, woody and apple-like.

    CONCLUSION: Inter-relationship between the aroma-active compounds and the pineapples revealed that 'Moris' and 'MD2' covaried majorly with the fruity esters, and the other varieties correlated with lesser numbers of the fruity esters. Hierarchical cluster analysis (HCA) was used to establish similarities among the pineapples and the results revealed three main groups of pineapples.

    Matched MeSH terms: 4-Butyrolactone
  8. Fulltext Cloning and Characterization of the Autoinducer Synthase Gene from Lipid-Degrading Bacterium Cedecea neteri
    Tan KH, How KY, Tan JY, Yin WF, Chan KG
    Front Microbiol, 2017;8:72.
    PMID: 28197135 DOI: 10.3389/fmicb.2017.00072
    The process of intercellular communication among bacteria, termed quorum sensing (QS), is mediated by small diffusible molecules known as the autoinducers. QS allows the population to react to the change of cell density in unison, in processes such as biofilm formation, plasmid conjugation, virulence, motility and root nodulation. In Gram-negative proteobacteria, N-acyl homoserine lactone (AHL) is the common "language" to coordinate gene expression. This signaling molecule is usually synthesized by LuxI-type proteins. We have previously discovered that a rare bacterium, Cedecea neteri, exhibits AHL-type QS activity. With information generated from genome sequencing, we have identified the luxIR gene pair responsible for AHL-type QS and named it cneIR. In this study, we have cloned and expressed the 636 bp luxI homolog in an Escherichia coli host for further characterization. Our findings show that E. coli harboring cneI produced the same AHL profile as the wild type C. neteri, with the synthesis of AHL known as N-butyryl-homoserine lactone. This 25 kDa LuxI homolog shares high similarity with other AHL synthases from closely related species. This work is the first documentation of molecular cloning and characterization of luxI homolog from C. neteri.
    Matched MeSH terms: 4-Butyrolactone
  9. Coexistence of quorum-quenching and quorum-sensing in tropical marine Pseudomonas aeruginosa strain MW3A
    Wong CS, Yin WF, Choo YM, Sam CK, Koh CL, Chan KG
    World J Microbiol Biotechnol, 2012 Feb;28(2):453-61.
    PMID: 22806840 DOI: 10.1007/s11274-011-0836-x
    A chemically defined medium called KGm medium was used to isolate from a sample of sea water a bacterial strain, MW3A, capable of using N-3-oxohexanoyl-L: -homoserine lactone as the sole carbon source. MW3A was clustered closely to Pseudomonas aeruginosa by 16S ribosomal DNA sequence analysis. It degraded both N-acylhomoserine lactones (AHLs) with a 3-oxo group substitution and, less preferably, AHLs with unsubstituted groups at C3 position in the acyl side chain, as determined by Rapid Resolution Liquid Chromatography. Its quiP and pvdQ homologue gene sequences showed high similarities to those of known acylases. Spent supernatant of MW3A harvested at 8-h post inoculation was shown to contain long-chain AHLs when assayed with the biosensor Escherichia coli [pSB1075], and specifically N-dodecanoyl-L: -homoserine lactone and N-3-oxotetradecanoyl-L: -homoserine lactone by high resolution mass spectrometry. Hence, we report here a novel marine P. aeruginosa strain MW3A possessing both quorum-quenching and quorum-sensing properties.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives; 4-Butyrolactone/metabolism
  10. Fulltext Complete genome sequencing of Pandoraea pnomenusa RB38 and Molecular Characterization of Its N-acyl homoserine lactone synthase gene ppnI
    Lim YL, Ee R, How KY, Lee SK, Yong D, Tee KK, et al.
    PeerJ, 2015;3:e1225.
    PMID: 26336650 DOI: 10.7717/peerj.1225
    In this study, we sequenced the genome of Pandoraea pnomenusa RB38 using Pacific Biosciences RSII (PacBio) Single Molecule Real Time (SMRT) sequencing technology. A pair of cognate luxI/R homologs was identified where the luxI homolog, ppnI, was found adjacent to a luxR homolog, ppnR1. An additional orphan luxR homolog, ppnR2, was also discovered. Multiple sequence alignment and phylogenetic analysis revealed that ppnI is an N-acyl homoserine lactone (AHL) synthase gene that is distinct from those of the nearest phylogenetic neighbor viz. Burkholderia spp. High resolution tandem mass spectrometry (LC-MS/MS) analysis showed that Escherichia coli BL21 harboring ppnI produced a similar AHL profile (N-octanoylhomoserine lactone, C8-HSL) as P. pnomenusa RB38, the wild-type donor strain, confirming that PpnI directed the synthesis of AHL in P. pnomenusa RB38. To our knowledge, this is the first documentation of the luxI/R homologs of the genus Pandoraea.
    Matched MeSH terms: 4-Butyrolactone
  11. Fulltext Discovery of Pantoea rodasii strain ND03 that produces N-(3-Oxo-hexanoyl)-L-homoserine lactone
    Yunos NY, Tan WS, Mohamad NI, Tan PW, Adrian TG, Yin WF, et al.
    Sensors (Basel), 2014;14(5):9145-52.
    PMID: 24859023 DOI: 10.3390/s140509145
    Proteobacteria use quorum sensing to regulate target gene expression in response to population density. Quorum sensing (QS) is achieved via so-called signalling molecules and the best-studied QS signalling system uses N-acyl homoserine lactones (AHLs). This study aimed to identify and characterize the production of AHLs by a bacterium ND03 isolated from a Malaysian tropical rainforest waterfall. Molecular identification showed that ND03 is a Pantoea sp. closely related to Pantoea rodasii. We used Chromobacterium violaceum CV026, an AHL biosensor for preliminary AHL production screening and then used high resolution triple quadrupole liquid chromatography-mass spectrometry, to confirm that P. rodasii strain ND03 produced N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL). To the best of our knowledge, this is the first report for such a discovery in P. rodasii strain ND03.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives*; 4-Butyrolactone/metabolism
  12. Fulltext Draft Genome Sequence of Jeotgalibacillus soli DSM 23228, a Bacterium Isolated from Alkaline Sandy Soil
    Goh KM, Chan KG, Yaakop AS, Chan CS, Ee R, Tan WS, et al.
    Genome Announc, 2015;3(3).
    PMID: 25999554 DOI: 10.1128/genomeA.00512-15
    Jeotgalibacillus soli, a bacterium capable of degrading N-acyl homoserine lactone, was isolated from a soil sample in Portugal. J. soli constitutes the only Jeotgalibacillus species isolated from a non-marine source. Here, the draft genome, several interesting glycosyl hydrolases, and its putative N-acyl homoserine lactonases are presented.
    Matched MeSH terms: 4-Butyrolactone
  13. Fulltext Electrospun Pectin-Polyhydroxybutyrate Nanofibers for Retinal Tissue Engineering
    Chan SY, Chan BQY, Liu Z, Parikh BH, Zhang K, Lin Q, et al.
    ACS Omega, 2017 Dec 31;2(12):8959-8968.
    PMID: 30023596 DOI: 10.1021/acsomega.7b01604
    Natural polysaccharide pectin has for the first time been grafted with polyhydroxybutyrate (PHB) via ring-opening polymerization of β-butyrolactone. This copolymer, pectin-polyhydroxybutyrate (pec-PHB), was blended with PHB in various proportions and electrospun to produce nanofibers that exhibited uniform and bead-free nanostructures, suggesting the miscibility of PHB and pec-PHB. These nanofiber blends exhibited reduced fiber diameters from 499 to 336-426 nm and water contact angles from 123.8 to 88.2° on incorporation of pec-PHB. They also displayed 39-335% enhancement of elongation at break relative to pristine PHB nanofibers. pec-PHB nanofibers were found to be noncytotoxic and biocompatible. Human retinal pigmented epithelium (ARPE-19) cells were seeded onto pristine PHB and pec-PHB nanofibers as scaffold and showed good proliferation. Higher proportions of pec-PHB (pec-PHB10 and pec-PHB20) yielded higher densities of cells with similar characteristics to normal RPE cells. We propose, therefore, that nanofibers of pec-PHB have significant potential as retinal tissue engineering scaffold materials.
    Matched MeSH terms: 4-Butyrolactone
  14. Fulltext Functional characterization of quorum sensing LuxR-type transcriptional regulator, EasR in Enterobacter asburiae strain L1
    Lau YY, How KY, Yin WF, Chan KG
    PeerJ, 2020;8:e10068.
    PMID: 33150063 DOI: 10.7717/peerj.10068
    Over the past decades, Enterobacter spp. have been identified as challenging and important pathogens. The emergence of multidrug-resistant Enterobacteria especially those that produce Klebsiella pneumoniae carbapenemase has been a very worrying health crisis. Although efforts have been made to unravel the complex mechanisms that contribute to the pathogenicity of different Enterobacter spp., there is very little information associated with AHL-type QS mechanism in Enterobacter spp. Signaling via N-acyl homoserine lactone (AHL) is the most common quorum sensing (QS) mechanism utilized by Proteobacteria. A typical AHL-based QS system involves two key players: a luxI gene homolog to synthesize AHLs and a luxR gene homolog, an AHL-dependent transcriptional regulator. These signaling molecules enable inter-species and intra-species interaction in response to external stimuli according to population density. In our recent study, we reported the genome of AHL-producing bacterium, Enterobacter asburiae strain L1. Whole genome sequencing and in silico analysis revealed the presence of a pair of luxI/R genes responsible for AHL-type QS, designated as easI/R, in strain L1. In a QS system, a LuxR transcriptional protein detects and responds to the concentration of a specific AHL controlling gene expression. In E. asburiae strain L1, EasR protein binds to its cognate AHLs, N-butanoyl homoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL), modulating the expression of targeted genes. In this current work, we have cloned the 693 bp luxR homolog of strain L1 for further characterization. The functionality and specificity of EasR protein in response to different AHL signaling molecules to activate gene transcription were tested and validated with β-galactosidase assays. Higher β-galactosidase activities were detected for cells harboring EasR, indicating EasR is a functional transcriptional regulator. This is the first report documenting the cloning and characterization of transcriptional regulator, luxR homolog of E. asburiae.
    Matched MeSH terms: 4-Butyrolactone
  15. Fulltext Genome analysis of quorum sensing Cedecea neteri SSMD04 leads to identification of its novel signaling synthase (cneI), cognate receptor (cneR) and an orphan receptor
    Tan KH, Tan JY, Yin WF, Chan KG
    PeerJ, 2015;3:e1216.
    PMID: 26355540 DOI: 10.7717/peerj.1216
    Cedecea neteri is a very rare human pathogen. We have isolated a strain of C. neteri SSMD04 from pickled mackerel sashimi identified using molecular and phenotypics approaches. Using the biosensor Chromobacterium violaceum CV026, we have demonstrated the presence of short chain N-acyl-homoserine lactone (AHL) type quorum sensing (QS) activity in C. neteri SSMD04. Triple quadrupole LC/MS analysis revealed that C. neteri SSMD04 produced short chain N-butyryl-homoserine lactone (C4-HSL). With the available genome information of C. neteri SSMD04, we went on to analyse and identified a pair of luxI/R homologues in this genome that share the highest similarity with croI/R homologues from Citrobacter rodentium. The AHL synthase, which we named cneI(636 bp), was found in the genome sequences of C. neteri SSMD04. At a distance of 8bp from cneI is a sequence encoding a hypothetical protein, potentially the cognate receptor, a luxR homologue which we named it as cneR. Analysis of this protein amino acid sequence reveals two signature domains, the autoinducer-binding domain and the C-terminal effector which is typical characteristic of luxR. In addition, we found that this genome harboured an orphan luxR that is most closely related to easR in Enterobacter asburiae. To our knowledge, this is the first report on the AHL production activity in C. neteri, and the discovery of its luxI/R homologues, the orphan receptor and its whole genome sequence.
    Matched MeSH terms: 4-Butyrolactone
  16. Fulltext Inhibiting N-acyl-homoserine lactone synthesis and quenching Pseudomonas quinolone quorum sensing to attenuate virulence
    Chan KG, Liu YC, Chang CY
    Front Microbiol, 2015;6:1173.
    PMID: 26539190 DOI: 10.3389/fmicb.2015.01173
    Bacteria sense their own population size, tune the expression of responding genes, and behave accordingly to environmental stimuli by secreting signaling molecules. This phenomenon is termed as quorum sensing (QS). By exogenously manipulating the signal transduction bacterial population behaviors could be controlled, which may be done through quorum quenching (QQ). QS related regulatory networks have been proven their involvement in regulating many virulence determinants in pathogenic bacteria in the course of infections. Interfering with QS signaling system could be a novel strategy against bacterial infections and therefore requires more understanding of their fundamental mechanisms. Here we review the development of studies specifically on the inhibition of production of N-acyl-homoserine lactone (AHL), a common proteobacterial QS signal. The opportunistic pathogen, Pseudomonas aeruginosa, equips the alkylquinolone (AQ)-mediated QS which also plays crucial roles in its pathogenicity. The studies in QQ targeting on AQ are also discussed.
    Matched MeSH terms: 4-Butyrolactone
  17. Isolation of AHL-degrading bacteria from micro-algal cultures and their impact on algal growth and on virulence of Vibrio campbellii to prawn larvae
    Pande GS, Natrah FM, Flandez AV, Kumar U, Niu Y, Bossier P, et al.
    Appl Microbiol Biotechnol, 2015 Dec;99(24):10805-13.
    PMID: 26344339 DOI: 10.1007/s00253-015-6918-1
    Inactivation of quorum sensing (QS) signal molecules, such as acylhomoserine lactones (AHLs) of pathogenic bacteria, has been proposed as a novel method to combat bacterial diseases in aquaculture. Despite the importance of micro-algae for aquaculture, AHL degradation by bacteria associated with micro-algal cultures has thus far not been investigated. In this study, we isolated Pseudomonas sp. NFMI-T and Bacillus sp. NFMI-C from open cultures of the micro-algae Tetraselmis suecica and Chaetoceros muelleri, respectively. An AHL degradation assay showed that either monocultures or co-cultures of the isolates were able to degrade the AHL N-hexanoyl-L-homoserine lactone. In contrast, only Bacillus sp. NFMI-C was able to inactivate N-hydroxybutanoyl-L-homoserine lactone, the AHL produced by Vibrio campbellii. The isolated bacteria were able to persist for up to 3 weeks in conventionalized micro-algal cultures, indicating that they were able to establish and maintain themselves within open algal cultures. Using gnotobiotic algal cultures, we found that the isolates did not affect growth of the micro-algae from which they were isolated, whereas a mixture of both isolates increased the growth of Tetraselmis and decreased the growth of Chaetoceros. Finally, addition of Bacillus sp. NFMI-C to the rearing water of giant river prawn (Macrobrachium rosenbergii) larvae significantly improved survival of the larvae when challenged with pathogenic V. campbellii, whereas it had no effect on larval growth.
    Matched MeSH terms: 4-Butyrolactone
  18. Fulltext Long chain N-acyl homoserine lactone production by Enterobacter sp. isolated from human tongue surfaces
    Yin WF, Purmal K, Chin S, Chan XY, Chan KG
    Sensors (Basel), 2012;12(11):14307-14.
    PMID: 23202161 DOI: 10.3390/s121114307
    We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives*; 4-Butyrolactone/biosynthesis
  19. Malabaricone C from Myristica cinnamomea exhibits anti-quorum sensing activity
    Chong YM, Yin WF, Ho CY, Mustafa MR, Hadi AH, Awang K, et al.
    J Nat Prod, 2011 Oct 28;74(10):2261-4.
    PMID: 21910441 DOI: 10.1021/np100872k
    A methanol-soluble extract of the bark of Myristica cinnamomea was found to exhibit anti-quorum sensing activity, and subsequent bioassay-guided isolation led to the identification of the active compound malabaricone C (1). Compound 1 inhibited violacein production by Chromobacterium violaceum CV026 when grown in the presence of a cognate signaling molecule, N-3-oxohexanoyl-homoserine lactone. Furthermore, 1 inhibited the quorum sensing-regulated pyocyanin production and biofilm formation in Pseudomonas aeruginosa PAO1. These results suggest that the anti-quorum sensing activity of 1 and related molecules should be investigated further.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives; 4-Butyrolactone/metabolism
  20. Fulltext N-acyl homoserine lactone-producing Pseudomonas putida strain T2-2 from human tongue surface
    Chen JW, Chin S, Tee KK, Yin WF, Choo YM, Chan KG
    Sensors (Basel), 2013;13(10):13192-203.
    PMID: 24084113 DOI: 10.3390/s131013192
    Bacterial cell-to-cell communication (quorum sensing) refers to the regulation of bacterial gene expression in response to changes in microbial population density. Quorum sensing bacteria produce, release and respond to chemical signal molecules called autoinducers. Bacteria use two types of autoinducers, namely autoinducer-1 (AI-1) and autoinducer-2 (AI-2) where the former are N-acylhomoserine lactones and the latter is a product of the luxS gene. Most of the reported literatures show that the majority of oral bacteria use AI-2 for quorum sensing but rarely the AI-1 system. Here we report the isolation of Pseudomonas putida strain T2-2 from the oral cavity. Using high resolution mass spectrometry, it is shown that this isolate produced N-octanoylhomoserine lactone (C8-HSL) and N-dodecanoylhomoserine lactone (C12-HSL) molecules. This is the first report of the finding of quorum sensing of P. putida strain T2-2 isolated from the human tongue surface and their quorum sensing molecules were identified.
    Matched MeSH terms: 4-Butyrolactone/analogs & derivatives*; 4-Butyrolactone/metabolism
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