MyMedR

Fulltext Whole genome analysis of Klebsiella pneumoniae T2-1-1 from human oral cavity

Chan KG, Yin WF, Chan XY

Genom Data, 2016 Mar;7:105-6.

PMID: 26981378 DOI: 10.1016/j.gdata.2015.12.008

Klebsiella pneumoniae T2-1-1 was isolated from the human tongue debris and subjected to whole genome sequencing on HiSeq platform and annotated on RAST. The nucleotide sequence of this genome was deposited into DDBJ/EMBL/GenBank under the accession JAQL00000000.

Fulltext Draft Genome Sequence of Quorum-Sensing and Quorum-Quenching Pseudomonas aeruginosa Strain MW3a

Chan KG, Wong CS, Yin WF, Chan XY

Genome Announc, 2014;2(2).

PMID: 24744329 DOI: 10.1128/genomeA.00258-14

Pseudomonas aeruginosa has a broad range of habitation, from aquatic environments to human lungs. The coexistence of quorum-sensing and quorum-quenching activities occurs in P. aeruginosa strain MW3a. In this work, we present the draft genome sequence of P. aeruginosa MW3a, an interesting bacterium isolated from a marine environment.

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.

Fulltext Microbiome and Biocatalytic Bacteria in Monkey Cup (Nepenthes Pitcher) Digestive Fluid

Chan XY, Hong KW, Yin WF, Chan KG

Sci Rep, 2016 Jan 28;6:20016.

PMID: 26817720 DOI: 10.1038/srep20016

Tropical carnivorous plant, Nepenthes, locally known as "monkey cup", utilises its pitcher as a passive trap to capture insects. It then secretes enzymes into the pitcher fluid to digest the insects for nutrients acquisition. However, little is known about the microbiota and their activity in its pitcher fluid. Eighteen bacteria phyla were detected from the metagenome study in the Nepenthes pitcher fluid. Proteobacteria, Bacteroidetes and Actinobacteria are the dominant phyla in the Nepenthes pitcher fluid. We also performed culturomics approach by isolating 18 bacteria from the Nepenthes pitcher fluid. Most of the bacterial isolates possess chitinolytic, proteolytic, amylolytic, and cellulolytic and xylanolytic activities. Fifteen putative chitinase genes were identified from the whole genome analysis on the genomes of the 18 bacteria isolated from Nepenthes pitcher fluid and expressed for chitinase assay. Of these, six clones possessed chitinase activity. In conclusion, our metagenome result shows that the Nepenthes pitcher fluid contains vast bacterial diversity and the culturomic studies confirmed the presence of biocatalytic bacteria within the Nepenthes pitcher juice which may act in symbiosis for the turn over of insects trapped in the Nepenthes pitcher fluid.

Fulltext N-Acyl Homoserine Lactone-Mediated Quorum Sensing in Aeromonas veronii biovar sobria Strain 159: Identification of LuxRI Homologs

Chan XY, How KY, Yin WF, Chan KG

Front Cell Infect Microbiol, 2016;6:7.

PMID: 26909339 DOI: 10.3389/fcimb.2016.00007

Vitellibacter aquimaris sp. nov., a marine bacterium isolated from seawater

Thevarajoo S, Selvaratnam C, Goh KM, Hong KW, Chan XY, Chan KG, et al.

Int J Syst Evol Microbiol, 2016 Sep;66(9):3662-3668.

PMID: 27334651 DOI: 10.1099/ijsem.0.001248

A Gram-staining-negative, aerobic, yellow-orange-pigmented, rod-shaped bacterium designated D-24T was isolated from seawater from sandy shoreline in Johor, Malaysia. The 16S rRNA gene sequence analysis revealed that strain D-24T is affiliated with the genus Vitellibacter. It shared more than 96 % sequence similarity with the types of some of the validly published species of the genus: Vitellibactervladivostokensis KMM 3516T (99.5 %), Vitellibactersoesokkakensis RSSK-12T (97.3 %), VitellibacterechinoideorumCC-CZW007T (96.9 %), VitellibacternionensisVBW088T (96.7 %) and Vitellibacteraestuarii JCM 15496T (96.3 %). DNA-DNA hybridization and genome-based analysis of average nucleotide identity (ANI) of strain D-24T versus V.vladivostokensisKMM 3516T exhibited values of 35.9±0.14 % and 89.26 %, respectively. Strain D-24T showed an even lower ANI value of 80.88 % with V. soesokkakensis RSSK-12T. The major menaquinone of strain D-24T was MK-6, and the predominant fatty acids were iso-C15 : 0 and iso-C17 : 0 3-OH. Strain D-24T contained major amounts of phosphatidylethanolamine, two lipids and two aminolipids, and a phosphoglycolipid that was different to that of other species of the genus Vitellibacter. The genomic DNA G+C content was 40.6 mol%. On the basis of phenotypic properties, DNA-DNA relatedness, ANI value and chemotaxonomic analyses, strain D-24T represents a novel species of the genus Vitellibacter, for which the name Vitellibacter aquimaris sp. nov. is proposed. The type strain is D-24T (=KCTC 42708T=DSM 101732T).

Fulltext Whole-Genome Analysis of Aeromonas hydrophila Strain 187, Exhibiting Quorum-Sensing Activity

Chan XY, Chua KH, Yin WF, Puthucheary SD, Chan KG

Genome Announc, 2014;2(6).

PMID: 25540357 DOI: 10.1128/genomeA.01360-14

Aeromonas hydrophila is a quorum-sensing (QS) bacterium that causes diarrhea in humans upon infection. Here, we report the genome of pathogenic Aeromonas hydrophila strain 187, which possesses a QS gene responsible for signaling molecule N-acyl homoserine lactone (AHL) synthesis and has been found to be located at contig 36.

Fulltext Whole-Genome Analysis of Quorum-Sensing Burkholderia sp. Strain A9

Chan KG, Chen JW, Tee KK, Chang CY, Yin WF, Chan XY

Genome Announc, 2015;3(2).

PMID: 25745000 DOI: 10.1128/genomeA.00063-15

Burkholderia spp. rely on N-acyl homoserine lactone as quorum-sensing signal molecules which coordinate their phenotype at the population level. In this work, we present the whole genome of Burkholderia sp. strain A9, which enables the discovery of its N-acyl homoserine lactone synthase gene.

Fulltext Global genome comparative analysis reveals insights of resistome and life-style adaptation of Pseudomonas putida strain T2-2 in oral cavity

Chan XY, Chua KO, How KY, Yin WF, Chan KG

ScientificWorldJournal, 2014;2014:930727.

PMID: 25436236 DOI: 10.1155/2014/930727

Most Pseudomonas putida strains are environmental microorganisms exhibiting a wide range of metabolic capability but certain strains have been reported as rare opportunistic pathogens and some emerged as multidrug resistant P. putida. This study aimed to assess the drug resistance profile of, via whole genome analysis, P. putida strain T2-2 isolated from oral cavity. At the same time, we also compared the nonenvironmental strain with environmentally isolated P. putida. In silico comparative genome analysis with available reference strains of P. putida shows that T2-2 has lesser gene counts on carbohydrate and aromatic compounds metabolisms, which suggested its little versatility. The detection of its edd gene also suggested T2-2's catabolism of glucose via ED pathway instead of EMP pathway. On the other hand, its drug resistance profile was observed via in silico gene prediction and most of the genes found were in agreement with drug-susceptibility testing in laboratory by automated VITEK 2. In addition, the finding of putative genes of multidrug resistance efflux pump and ATP-binding cassette transporters in this strain suggests a multidrug resistant phenotype. In summary, it is believed that multiple metabolic characteristics and drug resistance in P. putida strain T2-2 helped in its survival in human oral cavity.

Fulltext Labrenzia sp. BM1: a quorum quenching bacterium that degrades N-acyl homoserine lactones via lactonase activity

Ghani NA, Norizan SN, Chan XY, Yin WF, Chan KG

Sensors (Basel), 2014;14(7):11760-9.

PMID: 24995373 DOI: 10.3390/s140711760

We report the degradation of quorum sensing N-acylhomoserine lactone molecules by a bacterium isolated from a Malaysian marine water sample. MALDI-TOF and phylogenetic analysis indicated this isolate BM1 clustered closely to Labrenzia sp. The quorum quenching activity of this isolate was confirmed by using a series of bioassays and rapid resolution liquid chromatography analysis. Labrenzia sp. degraded a wide range of N-acylhomoserine lactones namely N-(3-hexanoyl)-L-homoserine lactone (C6-HSL), N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-(3-hydroxyhexanoyl)-L-homoserine lactone (3-hydroxy-C6-HSL). Re-lactonisation bioassays confirmed Labrenzia sp. BM1 degraded these signalling molecules efficiently via lactonase activity. To the best of our knowledge, this is the first documentation of a Labrenzia sp. capable of degrading N-acylhomoserine lactones and confirmation of its lactonase-based mechanism of action.

Fulltext Rhodotorula mucilaginosa, a quorum quenching yeast exhibiting lactonase activity isolated from a tropical shoreline

Ghani NA, Sulaiman J, Ismail Z, Chan XY, Yin WF, Chan KG

Sensors (Basel), 2014;14(4):6463-73.

PMID: 24721765 DOI: 10.3390/s140406463

Two microbial isolates from a Malaysian shoreline were found to be capable of degrading N-acylhomoserine lactones. Both Matrix Assisted Laser Desorption Ionization-Time of Flight-Mass Spectrometry and 18S rDNA phylogenetic analyses confirmed that these isolates are Rhodotorula mucilaginosa. Quorum quenching activities were detected by a series of bioassays and rapid resolution liquid chromatography analysis. The isolates were able to degrade various quorum sensing molecules namely N-hexanoyl-L-homoserine lactone (C6-HSL), N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-(3-hydroxyhexanoyl)-L-homoserine lactone (3-hydroxy-C6-HSL). Using a relactonisation assay to verify the quorum quenching mechanism, it is confirmed that Rh. mucilaginosa degrades the quorum sensing molecules via lactonase activity. To the best of our knowledge, this is the first documentation of the fact that Rh. mucilaginosa has activity against a broad range of AHLs namely C6-HSL, 3-oxo-C6-HSL and 3-hydroxy-C6-HSL.

Fulltext Metagenomic sequencing of prokaryotic microbiota from tropical surface seawater

Chan XY, Arumugam R, Choo SW, Yin WF, Chan KG

Genome Announc, 2013;1(4).

PMID: 23950114 DOI: 10.1128/genomeA.00540-13

Tropical seawater harbors a rich diversity of microorganisms as a result of its nutrient-rich environment, constant supply of sufficient sunlight, and warm climate. In this report, we present the complexity of the microbial diversity of the surface seawater of the Georgetown coast as determined using next-generation sequencing technology.

Fulltext Unusual long-chain N-acyl homoserine lactone production by and presence of quorum quenching activity in bacterial isolates from diseased tilapia fish

Chang CY, Koh CL, Sam CK, Chan XY, Yin WF, Chan KG

PLoS One, 2012;7(8):e44034.

PMID: 22952864 DOI: 10.1371/journal.pone.0044034

Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules.

Fulltext N-acyl homoserine lactone production by Klebsiella pneumoniae isolated from human tongue surface

Yin WF, Purmal K, Chin S, Chan XY, Koh CL, Sam CK, et al.

Sensors (Basel), 2012;12(3):3472-83.

PMID: 22737019 DOI: 10.3390/s120303472

Bacteria communicate by producing quorum sensing molecules called autoinducers, which include autoinducer-1, an N-hexanoyl homoserine lactone (AHL), and autoinducer-2. Bacteria present in the human oral cavity have been shown to produce autoinducer-2, but not AHL. Here, we report the isolation of two AHL-producing Klebsiella pneumoniae strains from the posterior dorsal surface of the tongue of a healthy individual. Spent culture supernatant extracts from K. pneumoniae activated the biosensors Agrobacterium tumefaciens NTL4(pZLR4) and Escherichia coli [pSB401], suggesting the presence of both long and short chain AHLs. High resolution mass spectrometry analyses of these extracts confirmed that both K. pneumoniae isolates produced N-octanoylhomoserine lactone and N-3-dodecanoyl-L-homoserine lactone. To the best of our knowledge, this is the first report of the isolation of K. pneumoniae from the posterior dorsal surface of the human tongue and the production of these AHLs by this bacterium.

Quorum sensing in Aeromonas species isolated from patients in Malaysia

Chan KG, Puthucheary SD, Chan XY, Yin WF, Wong CS, Too WS, et al.

Curr Microbiol, 2011 Jan;62(1):167-72.

PMID: 20544198 DOI: 10.1007/s00284-010-9689-z

Bacterial quorum sensing signal molecules called N-acylhomoserine lactone (AHL) controls the expression of virulence determinants in many Gram-negative bacteria. We determined AHL production in 22 Aeromonas strains isolated from various infected sites from patients (bile, blood, peritoneal fluid, pus, stool and urine). All isolates produced the two principal AHLs, N-butanoylhomoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL). Ten isolates also produced additional AHLs. This report is the first documentation of Aeromonas sobria producing C6-HSL and two additional AHLs with N-acyl side chain longer than C(6). Our data provides a better understanding of the mechanism(s) of this environmental bacterium emerging as a human pathogen.

Fulltext Draft Genome Sequence of Lysinibacillus sp. Strain A1, Isolated from Malaysian Tropical Soil

Chan KG, Chen JW, Chang CY, Yin WF, Chan XY

Genome Announc, 2015;3(2).

PMID: 25814592 DOI: 10.1128/genomeA.00095-15

In this work, we describe the genome of Lysinibacillus sp. strain A1, which was isolated from tropical soil. Analysis of its genome sequence shows the presence of a gene encoding for a putative peptidase responsible for nitrogen compounds.

Fulltext Insights of biosurfactant producing Serratia marcescens strain W2.3 isolated from diseased tilapia fish: a draft genome analysis

Chan XY, Chang CY, Hong KW, Tee KK, Yin WF, Chan KG

Gut Pathog, 2013;5(1):29.

PMID: 24148830 DOI: 10.1186/1757-4749-5-29

Serratia marcescens is an opportunistic bacterial pathogen with broad range of host ranging from vertebrates, invertebrates and plants. S. marcescens strain W2.3 was isolated from a diseased tilapia fish and it was suspected to be the causal agent for the fish disease as virulence genes were found within its genome. In this study, for the first time, the genome sequences of S. marcescens strain W2.3 were sequenced using the Illumina MiSeq platform.

Fulltext Chromosomal rearrangements and protein globularity changes in Mycobacterium tuberculosis isolates from cerebrospinal fluid

Saw SH, Tan JL, Chan XY, Chan KG, Ngeow YF

PeerJ, 2016;4:e2484.

PMID: 27688977 DOI: 10.7717/peerj.2484

BACKGROUND: Meningitis is a major cause of mortality in tuberculosis (TB). It is not clear what factors promote central nervous system invasion and pathology but it has been reported that certain strains of Mycobacterium tuberculosis (Mtb) might have genetic traits associated with neurotropism.

METHODS: In this study, we generated whole genome sequences of eight clinical strains of Mtb that were isolated from the cerebrospinal fluid (CSF) of patients presenting with tuberculous meningitis (TBM) in Malaysia, and compared them to the genomes of H37Rv and other respiratory Mtb genomes either downloaded from public databases or extracted from local sputum isolates. We aimed to find genomic features that might be distinctly different between CSF-derived and respiratory Mtb.

RESULTS: Genome-wide comparisons revealed rearrangements (translocations, inversions, insertions and deletions) and non-synonymous SNPs in our CSF-derived strains that were not observed in the respiratory Mtb genomes used for comparison. These rearranged segments were rich in genes for PE (proline-glutamate)/PPE (proline-proline-glutamate), transcriptional and membrane proteins. Similarly, most of the ns SNPs common in CSF strains were noted in genes encoding PE/PPE proteins. Protein globularity differences were observed among mycobacteria from CSF and respiratory sources and in proteins previously reported to be associated with TB meningitis. Transcription factors and other transcription regulators featured prominently in these proteins. Homologs of proteins associated with Streptococcus pneumoniae meningitis and Neisseria meningitidis virulence were identified in neuropathogenic as well as respiratory mycobacterial spp. examined in this study.

DISCUSSION: The occurrence of in silico genetic differences in CSF-derived but not respiratory Mtb suggests their possible involvement in the pathogenesis of TBM. However, overall findings in this comparative analysis support the postulation that TB meningeal infection is more likely to be related to the expression of multiple virulence factors on interaction with host defences than to CNS tropism associated with specific genetic traits.

Fulltext Whole-Genome Sequence and Fosfomycin Resistance of Bacillus sp. Strain G3(2015) Isolated from Seawater off the Coast of Malaysia

Chan XY, Chen JW, Adrian TG, Hong KW, Chang CY, Yin WF, et al.

Genome Announc, 2017 Mar 30;5(13).

PMID: 28360153 DOI: 10.1128/genomeA.00067-17

Bacillus sp. is a Gram-positive bacterium that is commonly found in seawater. In this study, the genome of marine Bacillus sp. strain G3(2015) was sequenced using MiSeq. The fosfomycin resistant gene fosB was identified upon bacterial genome annotation.

Fulltext Convergence between the microcosms of Southeast Asian and North American pitcher plants

Bittleston LS, Wolock CJ, Yahya BE, Chan XY, Chan KG, Pierce NE, et al.

Elife, 2018 08 28;7.

PMID: 30152327 DOI: 10.7554/eLife.36741

The 'pitchers' of carnivorous pitcher plants are exquisite examples of convergent evolution. An open question is whether the living communities housed in pitchers also converge in structure or function. Using samples from more than 330 field-collected pitchers of eight species of Southeast Asian Nepenthes and six species of North American Sarracenia, we demonstrate that the pitcher microcosms, or miniature ecosystems with complex communities, are strikingly similar. Compared to communities from surrounding habitats, pitcher communities house fewer species. While communities associated with the two genera contain different microbial organisms and arthropods, the species are predominantly from the same phylogenetic clades. Microbiomes from both genera are enriched in degradation pathways and have high abundances of key degradation enzymes. Moreover, in a manipulative field experiment, Nepenthes pitchers placed in a North American bog assembled Sarracenia-like communities. An understanding of the convergent interactions in pitcher microcosms facilitates identification of selective pressures shaping the communities.

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