Displaying publications 1 - 20 of 39 in total

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  1. See-Too WS, Salazar S, Ee R, Convey P, Chan KG, Peix Á
    Syst Appl Microbiol, 2017 Jun;40(4):191-198.
    PMID: 28501448 DOI: 10.1016/j.syapm.2017.03.002
    In this study we analysed three bacterial strains coded L10.10T, A4R1.5 and A4R1.12, isolated in the course of a study of quorum-quenching bacteria occurring in Antarctic soil. The 16S rRNA gene sequence was identical in the three strains and showed 99.7% pairwise similarity with respect to the closest related species Pseudomonas weihenstephanensis WS4993T. Therefore, the three strains were classified within the genus Pseudomonas. Analysis of housekeeping genes (rpoB, rpoD and gyrB) sequences showed similarities of 84-95% with respect to the closest related species of Pseudomonas, confirming its phylogenetic affiliation. The ANI values were less than 86% to the closest related species type strains. The respiratory quinone is Q9. The major fatty acids are C16:0, C16:1 ω7c/ C16:1 ω6c in summed feature 3 and C18:1 ω7c / C18:1 ω6c in summed feature 8. The strains are oxidase- and catalase-positive. Growth occurs at 4-30°C, and at pH 4.0-10. The DNA G+C content is 58.2-58.3mol %. The combined genotypic, phenotypic and chemotaxonomic data support the classification of strains L10.10T, A4R1.5 and A4R1.12 into a novel species of Pseudomonas, for which the name P. versuta sp. nov. is proposed. The type strain is L10.10T (LMG 29628T, DSM 101070T).
  2. See-Too WS, Ee R, Lim YL, Convey P, Pearce DA, Mohidin TBM, et al.
    Stand Genomic Sci, 2017;12:52.
    PMID: 28904741 DOI: 10.1186/s40793-017-0264-0
    Arthrobacter alpinus R3.8 is a psychrotolerant bacterial strain isolated from a soil sample obtained at Rothera Point, Adelaide Island, close to the Antarctic Peninsula. Strain R3.8 was sequenced in order to help discover potential cold active enzymes with biotechnological applications. Genome analysis identified various cold adaptation genes including some coding for anti-freeze proteins and cold-shock proteins, genes involved in bioremediation of xenobiotic compounds including naphthalene, and genes with chitinolytic and N-acetylglucosamine utilization properties and also plant-growth-influencing properties. In this genome report, we present a complete genome sequence of A. alpinus strain R3.8 and its annotation data, which will facilitate exploitation of potential novel cold-active enzymes.
  3. Cheng HJ, Ee R, Cheong YM, Tan WS, Yin WF, Chan KG
    Sensors (Basel), 2014;14(7):12511-22.
    PMID: 25019635 DOI: 10.3390/s140712511
    A multidrug-resistant clinical bacteria strain GB11 was isolated from a wound swab on the leg of a patient. Identity of stain GB11 as Pseudomonas aeruginosa was validated by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Detection of the production of signaling molecules, N-acylhomoserine lactones (AHLs), was conducted using three different bacterial biosensors. A total of four different AHLs were found to be produced by strain GB11, namely N-butyryl homoserine lactone (C4-HSL), N-hexanoylhomoserine lactone (C6-HSL), N-octanoyl homoserine lactone (C8-HSL) and N-3-oxo-dodecanoylhomoserine lactone (3-oxo-C12-HSL) using high resolution liquid chromatography tandem mass spectrometry (LC-MS/MS). Of these detected AHLs, 3-oxo-C12-HSL was found to be the most abundant AHL produced by P. aeruginosa GB11.
  4. Ee R, Lim YL, Kin LX, Yin WF, Chan KG
    Sensors (Basel), 2014;14(6):10177-86.
    PMID: 24919016 DOI: 10.3390/s140610177
    Strain RB38 was recovered from a former dumping area in Malaysia. MALDI-TOF mass spectrometry and genomic analysis identified strain RB-38 as Pandoraea pnomenusa. Various biosensors confirmed its quorum sensing properties. High resolution triple quadrupole liquid chromatography-mass spectrometry analysis was subsequently used to characterize the N-acyl homoserine lactone production profile of P. pnomenusa strain RB38, which validated that this isolate produced N-octanoyl homoserine lactone as a quorum sensing molecule. This is the first report of the production of N-octanoyl homoserine lactone by P. pnomenusa strain RB38.
  5. Lim YL, Ee R, Yin WF, Chan KG
    Sensors (Basel), 2014 Apr 22;14(4):7026-40.
    PMID: 24759107 DOI: 10.3390/s140407026
    Quorum sensing is a well-studied cell-to-cell communication method that involves a cell-density dependent regulation of genes expression mediated by signalling molecules. In this study, a bacterium isolated from a plant material compost pile was found to possess quorum sensing activity based on bioassay screening. Isolate YL12 was identified using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and molecular typing using rpoD gene which identified the isolate as Aeromonas caviae. High resolution tandem mass spectrometry was subsequently employed to identify the N-acyl homoserine lactone profile of Aeromonas caviae YL12 and confirmed that this isolate produced two short chain N-acyl homoserine lactones, namely C4-HSL and C6, and the production was observed to be cell density-dependent. Using the thin layer chromatography (TLC) bioassay, both AHLs were found to activate C. violaceum CV026, whereas only C6-HSL was revealed to induce bioluminescence expression of E. coli [pSB401]. The data presented in this study will be the leading steps in understanding the role of quorum sensing in Aeromonas caviae strain YL12.
  6. Ee R, Lim YL, Tee KK, Yin WF, Chan KG
    Sensors (Basel), 2014 Mar 12;14(3):5136-46.
    PMID: 24625739 DOI: 10.3390/s140305136
    Quorum sensing is a unique bacterial communication system which permits bacteria to synchronize their behaviour in accordance with the population density. The operation of this communication network involves the use of diffusible autoinducer molecules, termed N-acylhomoserine lactones (AHLs). Serratia spp. are well known for their use of quorum sensing to regulate the expression of various genes. In this study, we aimed to characterized the AHL production of a bacterium designated as strain RB-25 isolated from a former domestic waste landfill site. It was identified as Serratia fonticola using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry analysis and this was confirmed by 16S ribosomal DNA sequencing. High resolution triple quadrupole liquid chromatography-mass spectrometry analysis of S. fonticola strain RB-25 spent culture supernatant indicated the existence of three AHLs namely: N-butyryl-L-homoserine lactone (C4-HSL), N-hexanoyl-L-homoserine lactone (C6-HSL) and N-(3-oxohexanoyl) homoserine-lactone (3-oxo-C6 HSL). This is the first report of the production of these AHLs in S. fonticola.
  7. Young ND, Chan KG, Korhonen PK, Min Chong T, Ee R, Mohandas N, et al.
    Sci Rep, 2015;5:17345.
    PMID: 26621075 DOI: 10.1038/srep17345
    Schistosomiasis is a neglected tropical disease that affects more than 200 million people worldwide. The main disease-causing agents, Schistosoma japonicum, S. mansoni and S. haematobium, are blood flukes that have complex life cycles involving a snail intermediate host. In Asia, S. japonicum causes hepatointestinal disease (schistosomiasis japonica) and is challenging to control due to a broad distribution of its snail hosts and range of animal reservoir hosts. In China, extensive efforts have been underway to control this parasite, but genetic variability in S. japonicum populations could represent an obstacle to eliminating schistosomiasis japonica. Although a draft genome sequence is available for S. japonicum, there has been no previous study of molecular variation in this parasite on a genome-wide scale. In this study, we conducted the first deep genomic exploration of seven S. japonicum populations from mainland China, constructed phylogenies using mitochondrial and nuclear genomic data sets, and established considerable variation between some of the populations in genes inferred to be linked to key cellular processes and/or pathogen-host interactions. Based on the findings from this study, we propose that verifying intraspecific conservation in vaccine or drug target candidates is an important first step toward developing effective vaccines and chemotherapies against schistosomiasis.
  8. Yaakop AS, Chan KG, Ee R, Lim YL, Lee SK, Manan FA, et al.
    Sci Rep, 2016 09 19;6:33660.
    PMID: 27641516 DOI: 10.1038/srep33660
    Jeotgalibacillus malaysiensis, a moderate halophilic bacterium isolated from a pelagic area, can endure higher concentrations of sodium chloride (NaCl) than other Jeotgalibacillus type strains. In this study, we therefore chose to sequence and assemble the entire J. malaysiensis genome. This is the first report to provide a detailed analysis of the genomic features of J. malaysiensis, and to perform genetic comparisons between this microorganism and other halophiles. J. malaysiensis encodes a native megaplasmid (pJeoMA), which is greater than 600 kilobases in size, that is absent from other sequenced species of Jeotgalibacillus. Subsequently, RNA-Seq-based transcriptome analysis was utilised to examine adaptations of J. malaysiensis to osmotic stress. Specifically, the eggNOG (evolutionary genealogy of genes: Non-supervised Orthologous Groups) and KEGG (Kyoto Encyclopaedia of Genes and Genomes) databases were used to elucidate the overall effects of osmotic stress on the organism. Generally, saline stress significantly affected carbohydrate, energy, and amino acid metabolism, as well as fatty acid biosynthesis. Our findings also indicate that J. malaysiensis adopted a combination of approaches, including the uptake or synthesis of osmoprotectants, for surviving salt stress. Among these, proline synthesis appeared to be the preferred method for withstanding prolonged osmotic stress in J. malaysiensis.
  9. 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.
  10. Maran S, Ee R, Faten SA, Sy Bing C, Khaw KY, Erin Lim SH, et al.
    PLoS One, 2020;15(4):e0230982.
    PMID: 32315303 DOI: 10.1371/journal.pone.0230982
    Atrial septal defect (ASD) is one of the most common congenital heart defects diagnosed in children. Sarcomeric genes has been attributed to ASD and knockdown of MYH3 functionally homologues gene in chick models indicated abnormal atrial septal development. Here, we report for the first time, a case-control study investigating the role of MYH3 among non-syndromic ASD patients in contributing to septal development. Four amplicons which will amplifies the 40 kb MYH3 were designed and amplified using long range-PCR. The amplicons were then sequenced using indexed paired-end libraries on the MiSeq platform. The STREGA guidelines were applied for planning and reporting. The non-synonymous c. 3574G>A (p.Ala1192Thr) [p = 0.001, OR = 2.30 (1.36-3.87)] located within the tail domain indicated a highly conserved protein region. The mutant model of c. 3574G>A (p.Ala1192Thr) showed high root mean square deviation (RMSD) values compared to the wild model. To our knowledge, this is the first study to provide compelling evidence on the pathogenesis of MYH3 variants towards ASD hence, suggesting the crucial role of non-synonymous variants in the tail domain of MYH3 towards atrial septal development. It is hoped that this gene can be used as panel for diagnosis of ASD in future.
  11. 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.
  12. See-Too WS, Tan JY, Ee R, Lim YL, Convey P, Pearce DA, et al.
    Mar Genomics, 2016 Apr 22.
    PMID: 27117861 DOI: 10.1016/j.margen.2016.04.007
    Planococcus kocurii ATCC 43650(T) is a halotolerant and psychrotolerant bacterium isolated from the skin of a North sea cod. Here, we present the first complete genome and annotation of P. kocurii ATCC 43650(T), identifying its potential as a plant growth promoting bacterium and its capability in the biosynthesis of butanol.
  13. Selvaratnam C, Thevarajoo S, Ee R, Chan KG, Bennett JP, Goh KM, et al.
    Mar Genomics, 2016 Apr 20.
    PMID: 27107724 DOI: 10.1016/j.margen.2016.04.004
    Roseivirga sp. strain D-25 is an aerobic marine bacterium isolated from seawater collected from Desaru beach, Malaysia. To date, the genus Roseivirga consists of only four species with no genome sequence reported. Here, we present the genome sequence of Roseivirga sp. strain D-25 (=KCTC 42709=DSM 101709), with a genome size of approximately 4.08Mbp and G+C content of 39.18%. Genome sequence analysis of strain D-25 revealed the presence of genes related to petroleum hydrocarbon degradation, 2,4,6-trinitrotoluene detoxification, heavy metals bioremediation and production of carotenoids, which shed light on the potential application of this strain.
  14. Goh KM, Chan KG, Yaakop AS, Ee R
    J Biotechnol, 2015 Jun 20;204:13-4.
    PMID: 25858153 DOI: 10.1016/j.jbiotec.2015.03.007
    Jeotgalibacillus spp. are halophilic bacteria within the family Planococcaceae. No genomes of Jeotgalibacillus spp. have been reported to date, and their metabolic pathways are unknown. How the bacteria survive in hypertonic conditions such as seawater is yet to be discovered. As only few studies have been conducted on Jeotgalibacillus spp., potential applications of these bacteria are unknown. Here, we present the complete genome of J. malaysiensis D5(T) (=DSM 28777(T) =KCTC 33350(T)), which is invaluable in identifying interesting applications for this genus.
  15. Ee R, Yong D, Lim YL, Yin WF, Chan KG
    J Biotechnol, 2015 Jun 20;204:5-6.
    PMID: 25848988 DOI: 10.1016/j.jbiotec.2015.03.020
    Pandoraea vervacti DSM 23571(T) is an oxalate metabolizing bacterium isolated from an uncultivated field soil in Mugla, Turkey. Here, we present the first complete genome sequence of P. vervacti DSM 23571(T). A complete pathway for degradation of oxalate was revealed from the genome analysis. These data are important to path new opportunities for genetic engineering in the field of biotechnology.
  16. See-Too WS, Lim YL, Ee R, Convey P, Pearce DA, Yin WF, et al.
    J Biotechnol, 2016 Mar 20;222:84-5.
    PMID: 26876481 DOI: 10.1016/j.jbiotec.2016.02.017
    Pseudomonas sp. strain L10.10 (=DSM 101070) is a psychrotolerant bacterium which was isolated from Lagoon Island, Antarctica. Analysis of its complete genome sequence indicates its possible role as a plant-growth promoting bacterium, including nitrogen-fixing ability and indole acetic acid (IAA)-producing trait, with additional suggestion of plant disease prevention attributes via hydrogen cyanide production.
  17. See-Too WS, Convey P, Pearce DA, Lim YL, Ee R, Yin WF, et al.
    J Biotechnol, 2016 Mar 10;221:114-5.
    PMID: 26808870 DOI: 10.1016/j.jbiotec.2016.01.026
    Planococcus rifietoensis M8(T) (=DSM 15069(T)=ATCC BAA-790(T)) is a halotolerant bacterium with potential plant growth promoting properties isolated from an algal mat collected from a sulfurous spring in Campania (Italy). This paper presents the first complete genome of P. rifietoensis M8(T). Genes coding for various potentially plant growth promoting properties were identified within its genome.
  18. Chan KG, Yong D, Ee R, Lim YL, Yu CY, Tee KK, et al.
    J Biotechnol, 2016 Feb 10;219:124-5.
    PMID: 26742625 DOI: 10.1016/j.jbiotec.2015.12.037
    Pandoraea oxalativorans DSM 23570(T) is an oxalate-degrading bacterium that was originally isolated from soil litter near to oxalate-producing plant of the genus Oxalis. Here, we report the first complete genome of P. oxalativorans DSM 23570(T) which would allow its potential biotechnological applications to be unravelled.
  19. Yong D, Ee R, Lim YL, Yu CY, Ang GY, How KY, et al.
    J Biotechnol, 2016 Jan 10;217:51-2.
    PMID: 26603120 DOI: 10.1016/j.jbiotec.2015.11.009
    Pandoraea thiooxydans DSM 25325(T) is a thiosulfate-oxidizing bacterium isolated from rhizosphere soils of a sesame plant. Here, we present the first complete genome of P. thiooxydans DSM 25325(T). Several genes involved in thiosulfate oxidation and biodegradation of aromatic compounds were identified.
  20. Lim YL, Ee R, Yong D, Tee KK, Yin WF, Chan KG
    J Biotechnol, 2015 Nov 20;214:83-4.
    PMID: 26393955 DOI: 10.1016/j.jbiotec.2015.09.018
    Pandoraea pnomenusa RB-38 is a bacterium isolated from a former sanitary landfill site. Here, we present the complete genome of P. pnomenusa RB38 in which an oxalate utilization pathway was identified. The genome analysis suggested the potential of this strain as an effective biocontrol agent against oxalate-producing phytopathogens.
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