Displaying publications 1 - 20 of 29 in total

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  1. Ng KP, Yew SM, Chan CL, Soo-Hoo TS, Na SL, Hassan H, et al.
    Eukaryotic Cell, 2012 Jun;11(6):828.
    PMID: 22645233 DOI: 10.1128/EC.00133-12
    Pleosporales is the largest order in the fungal class Dothideomycetes. We report the 36,814,818-bp draft genome sequence and gene annotation of UM1110, a Pleosporales isolate associated with unclassified genera that is potentially a new fungal species. Analysis of the genome sequence led to the finding of genes associated with fungal adhesive proteins, secreted proteases, allergens, and pseudohyphal development.
  2. Ng KP, Ngeow YF, Yew SM, Hassan H, Soo-Hoo TS, Na SL, et al.
    Eukaryotic Cell, 2012 May;11(5):703-4.
    PMID: 22544898 DOI: 10.1128/EC.00074-12
    Daldinia eschscholzii is an invasive endophyte that is most commonly found in plant tissues rich in secondary metabolites. We report the draft genome sequence of D. eschscholzii isolated from blood culture. The draft genome is 35,494,957 bp in length, with 42,898,665 reads, 61,449 contigs, and a G+C content of 46.8%. The genome was found to contain a high abundance of genes associated with plant cell wall degradation enzymes, mycotoxin production, and antifungal drug resistance.
  3. Ng KP, Yew SM, Chan CL, Soo-Hoo TS, Na SL, Hassan H, et al.
    Eukaryotic Cell, 2012 May;11(5):705-6.
    PMID: 22544899 DOI: 10.1128/EC.00081-12
    Cladosporium sphaerospermum is one of the most widely distributed allergens causing serious problems in patients with respiratory tract disease. We report the 26,644,473-bp draft genome sequence and gene annotation of C. sphaerospermum UM843. Analysis of the genome sequence led to the finding of genes associated with C. sphaerospermum's melanin biosynthesis, allergens, and antifungal drug resistance.
  4. Ng KP, Yew SM, Chan CL, Tan R, Soo-Hoo TS, Na SL, et al.
    Genome Announc, 2013 Jan;1(1).
    PMID: 23409267 DOI: 10.1128/genomeA.00148-12
    Herpotrichiellaceae spp. are known to be opportunistic human pathogens. Here, we report the ~28.46-Mb draft genome of Herpotrichiellaceae sp. UM 238, isolated from human skin scraping. The UM 238 genome was found to contain many classes of protective genes that are responsible for fungal adaptation under adverse environmental conditions.
  5. Ng KP, Yew SM, Chan CL, Chong J, Tang SN, Soo-Hoo TS, et al.
    Genome Announc, 2013 Jan;1(1).
    PMID: 23405310 DOI: 10.1128/genomeA.00056-12
    The emergence of the global threat of extensively drug-resistant (XDR) Mycobacterium tuberculosis reveals weaknesses in tuberculosis management and diagnostic services. We report the draft genome sequence of the first extensively drug-resistant Mycobacterium tuberculosis strain isolated in Malaysia. The sequence was also compared against a reference strain to elucidate the polymorphism that is related to their extensive resistance.
  6. Chow KS, Mat-Isa MN, Bahari A, Ghazali AK, Alias H, Mohd-Zainuddin Z, et al.
    J Exp Bot, 2012 Mar;63(5):1863-71.
    PMID: 22162870 DOI: 10.1093/jxb/err363
    The cytosolic mevalonate (MVA) pathway in Hevea brasiliensis latex is the conventionally accepted pathway which provides isopentenyl diphosphate (IPP) for cis-polyisoprene (rubber) biosynthesis. However, the plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway may be an alternative source of IPP since its more recent discovery in plants. Quantitative RT-PCR (qRT-PCR) expression profiles of genes from both pathways in latex showed that subcellular compartmentalization of IPP for cis-polyisoprene synthesis is related to the degree of plastidic carotenoid synthesis. From this, the occurrence of two schemes of IPP partitioning and utilization within one species is proposed whereby the supply of IPP for cis-polyisoprene from the MEP pathway is related to carotenoid production in latex. Subsequently, a set of latex unique gene transcripts was sequenced and assembled and they were then mapped to IPP-requiring pathways. Up to eight such pathways, including cis-polyisoprene biosynthesis, were identified. Our findings on pre- and post-IPP metabolic routes form an important aspect of a pathway knowledge-driven approach to enhancing cis-polyisoprene biosynthesis in transgenic rubber trees.
  7. Kuan CS, Ng KP, Yew SM, Umar Meleh H, Seow HF, How KN, et al.
    Braz J Microbiol, 2023 Sep;54(3):1351-1372.
    PMID: 37351789 DOI: 10.1007/s42770-023-01032-z
    Neoscytalidium dimidiatum and Bipolaris species are fungal plant pathogens that have been reported to cause human diseases. Recently, we have isolated numerous N. dimidiatum and Bipolaris species from the skin scrapings and nails of different patients. In this work, we have sequenced the genome of one strain of N. dimidiatum. The sequenced genome was compared to that of a previously reported Bipolaris papendorfii genome for a better understanding of their complex lifestyle and broad host-range pathogenicity. Both N. dimidiatum UM 880 (~ 43 Mb) and B. papendorfii UM 226 (~ 33 Mb) genomes include 11,015-12,320 putative coding DNA sequences, of which 0.51-2.49% are predicted transposable elements. Analysis of secondary metabolism gene clusters revealed several genes involved in melanin biosynthesis and iron uptake. The arsenal of CAZymes related to plants pathogenicity is comparable between the species, including genes involved in hemicellulose and pectin decomposition. Several important gene encoding keratinolytic peptidases were identified in N. dimidiatum and B. papendorfii, reflecting their potential pathogenic role in causing skin and nail infections. In this study, additional information on the metabolic features of these two species, such as nutritional profiling, pH tolerance, and osmotolerant, are revealed. The genomic characterization of N. dimidiatum and B. papendorfii provides the basis for the future functional studies to gain further insights as to what makes these fungi persist in plants and why they are pathogenic to humans.
  8. Tan IKP, Foong CP, Tan HT, Lim H, Zain NA, Tan YC, et al.
    J Biotechnol, 2020 Apr 10;313:18-28.
    PMID: 32171790 DOI: 10.1016/j.jbiotec.2020.03.006
    The polyhydroxyalkanoate (PHA) producing capability of four bacterial strains isolated from Antarctica was reported in a previous study. This study analyzed the PHA synthase genes and the PHA-associated gene clusters from the two antarctic Pseudomonas isolates (UMAB-08 and UMAB-40) and the two antarctic Janthinobacterium isolates (UMAB-56 and UMAB-60) through whole-genome sequence analysis. The Pseudomonas isolates were found to carry PHA synthase genes which fall into two different PHA gene clusters, namely Class I and Class II, which are involved in the biosynthesis of short-chain-length-PHA (SCL-PHA) and medium-chain-length-PHA (MCL-PHA), respectively. On the other hand, the Janthinobacterium isolates carry a Class I and an uncharacterized putative PHA synthase genes. No other gene involved in PHA synthesis was detected in close proximity to the uncharacterized putative PHA synthase gene in the Janthinobacterium isolates, therefore it falls into a separate clade from the ordinary Class I, II, III and IV clades of PHA synthase (PhaC) phylogenetic tree. Multiple sequence alignment showed that the uncharacterized putative PHA synthase gene contains all the highly conserved amino acid residues and the proposed catalytic triad of PHA synthase. PHA biosynthesis and in vitro PhaC enzymatic assay results showed that this uncharacterized putative PHA synthase from Janthinobacterium sp. UMAB-60 is funtional. This report adds new knowledge to the PHA synthase database as we describe scarce information of PHA synthase genes and PHA-associated gene clusters from the antarctic bacterial isolates (extreme and geographically isolated environment) and comparing with those from non-antarctic PHA-producing bacteria.
  9. Kuan CS, Ismail R, Kwan Z, Yew SM, Yeo SK, Chan CL, et al.
    PLoS One, 2016;11(6):e0156119.
    PMID: 27280438 DOI: 10.1371/journal.pone.0156119
    A yeast-like organism was isolated from the skin scraping sample of a stasis dermatitis patient in the Mycology Unit Department of Medical Microbiology, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. The isolate produced no pigment and was not identifiable using chromogenic agar and API 20C AUX. The fungus was identified as Metschnikowia sp. strain UM 1034, which is close to that of Metschnikowia drosophilae based on ITS- and D1/D2 domain-based phylogenetic analysis. However, the physiology of the strain was not associated to M. drosophilae. This pathogen exhibited low sensitivity to all tested azoles, echinocandins, 5-flucytosine and amphotericin B. This study provided insight into Metschnikowia sp. strain UM 1034 phenotype profiles using a Biolog phenotypic microarray (PM). The isolate utilized 373 nutrients of 760 nutrient sources and could adapt to a broad range of osmotic and pH environments. To our knowledge, this is the first report of the isolation of Metschnikowia non-pulcherrima sp. from skin scraping, revealing this rare yeast species as a potential human pathogen that may be misidentified as Candida sp. using conventional methods. Metschnikowia sp. strain UM 1034 can survive in flexible and diverse environments with a generalist lifestyle.
  10. Kuan CS, Yew SM, Toh YF, Chan CL, Lim SK, Lee KW, et al.
    PLoS One, 2015;10(12):e0145932.
    PMID: 26716988 DOI: 10.1371/journal.pone.0145932
    Peritonitis is the leading complication of peritoneal dialysis, which is primarily caused by bacteria rather than fungi. Peritonitis is responsible for approximately 18% of the infection-related mortality in peritoneal dialysis patients. In this paper, we report the isolation of a rare fungus, Quambalaria cyanescens, from the peritoneal fluid of a man after he switched from continuous ambulatory peritoneal dialysis to nocturnal intermittent peritoneal dialysis. Based on the morphological examination and multigene phylogeny, the clinical isolate was confirmed as Q. cyanescens. This pathogen exhibited low sensitivity to all tested echinocandins and 5-flucytosine. Interestingly, morphological characterization revealed that Q. cyanescens UM 1095 produced different pigments at low temperatures (25°C and 30°C) on various culture media. It is important to monitor the emergence of this rare fungus as a potential human pathogen in the tropics. This study provides insight into Q. cyanescens UM 1095 phenotype profiles using a Biolog phenotypic microarray (PM). Of the 760 nutrient sources tested, Q. cyanescens UM 1095 utilized 42 compounds, and the fungus can adapt to a broad range of osmotic and acidic environments. To our knowledge, this is the first report of the isolation of Q. cyanescens from peritoneal fluid, revealing this rare fungus as a potential human pathogen that may be misidentified using conventional methods. The detailed morphological, molecular and phenotypic characterization of Q. cyanescens UM 1095 provides the basis for future studies on its biology, lifestyle, and potential pathogenicity.
  11. Yew SM, Chan CL, Lee KW, Na SL, Tan R, Hoh CC, et al.
    PLoS One, 2014;9(8):e104352.
    PMID: 25098697 DOI: 10.1371/journal.pone.0104352
    Dematiaceous fungi (black fungi) are a heterogeneous group of fungi present in diverse environments worldwide. Many species in this group are known to cause allergic reactions and potentially fatal diseases in humans and animals, especially in tropical and subtropical climates. This study represents the first survey of dematiaceous fungi in Malaysia and provides observations on their diversity as well as in vitro response to antifungal drugs. Seventy-five strains isolated from various clinical specimens were identified by morphology as well as an internal transcribed spacer (ITS)-based phylogenetic analysis. The combined molecular and conventional approach enabled the identification of three classes of the Ascomycota phylum and 16 genera, the most common being Cladosporium, Cochliobolus and Neoscytalidium. Several of the species identified have not been associated before with human infections. Among 8 antifungal agents tested, the azoles posaconazole (96%), voriconazole (90.7%), ketoconazole (86.7%) and itraconazole (85.3%) showed in vitro activity (MIC ≤ 1 µg/mL) to the largest number of strains, followed by anidulafungin (89.3%), caspofungin (74.7%) and amphotericin B (70.7%). Fluconazole appeared to be the least effective with only 10.7% of isolates showing in vitro susceptibility. Overall, almost half (45.3%) of the isolates showed reduced susceptibility (MIC >1 µg/mL) to at least one antifungal agent, and three strains (one Pyrenochaeta unguis-hominis and two Nigrospora oryzae) showed potential multidrug resistance.
  12. Yew SM, Chan CL, Soo-Hoo TS, Na SL, Ong SS, Hassan H, et al.
    Genome Announc, 2013;1(3).
    PMID: 23723391 DOI: 10.1128/genomeA.00158-13
    Pyrenochaeta, classified under the order Pleosporales, is known to cause diseases in plants and humans. Here, we report a draft genome sequence of a Pyrenochaeta sp. isolated from a skin scraping, with an estimated genome size of 39.4 Mb. Genes associated with the synthesis of proteases, toxins, plant cell wall degradation, and multidrug resistance were found.
  13. Chan CL, Yew SM, Ngeow YF, Na SL, Lee KW, Hoh CC, et al.
    BMC Genomics, 2015 Nov 18;16:966.
    PMID: 26581579 DOI: 10.1186/s12864-015-2200-2
    BACKGROUND: Daldinia eschscholtzii is a wood-inhabiting fungus that causes wood decay under certain conditions. It has a broad host range and produces a large repertoire of potentially bioactive compounds. However, there is no extensive genome analysis on this fungal species.

    RESULTS: Two fungal isolates (UM 1400 and UM 1020) from human specimens were identified as Daldinia eschscholtzii by morphological features and ITS-based phylogenetic analysis. Both genomes were similar in size with 10,822 predicted genes in UM 1400 (35.8 Mb) and 11,120 predicted genes in UM 1020 (35.5 Mb). A total of 751 gene families were shared among both UM isolates, including gene families associated with fungus-host interactions. In the CAZyme comparative analysis, both genomes were found to contain arrays of CAZyme related to plant cell wall degradation. Genes encoding secreted peptidases were found in the genomes, which encode for the peptidases involved in the degradation of structural proteins in plant cell wall. In addition, arrays of secondary metabolite backbone genes were identified in both genomes, indicating of their potential to produce bioactive secondary metabolites. Both genomes also contained an abundance of gene encoding signaling components, with three proposed MAPK cascades involved in cell wall integrity, osmoregulation, and mating/filamentation. Besides genomic evidence for degrading capability, both isolates also harbored an array of genes encoding stress response proteins that are potentially significant for adaptation to living in the hostile environments.

    CONCLUSIONS: Our genomic studies provide further information for the biological understanding of the D. eschscholtzii and suggest that these wood-decaying fungi are also equipped for adaptation to adverse environments in the human host.

  14. Kuan CS, Yew SM, Chan CL, Toh YF, Lee KW, Cheong WH, et al.
    Database (Oxford), 2016;2016.
    PMID: 26980516 DOI: 10.1093/database/baw008
    Many species of dematiaceous fungi are associated with allergic reactions and potentially fatal diseases in human, especially in tropical climates. Over the past 10 years, we have isolated more than 400 dematiaceous fungi from various clinical samples. In this study, DemaDb, an integrated database was designed to support the integration and analysis of dematiaceous fungal genomes. A total of 92 072 putative genes and 6527 pathways that identified in eight dematiaceous fungi (Bipolaris papendorfii UM 226, Daldinia eschscholtzii UM 1400, D. eschscholtzii UM 1020, Pyrenochaeta unguis-hominis UM 256, Ochroconis mirabilis UM 578, Cladosporium sphaerospermum UM 843, Herpotrichiellaceae sp. UM 238 and Pleosporales sp. UM 1110) were deposited in DemaDb. DemaDb includes functional annotations for all predicted gene models in all genomes, such as Gene Ontology, EuKaryotic Orthologous Groups, Kyoto Encyclopedia of Genes and Genomes (KEGG), Pfam and InterProScan. All predicted protein models were further functionally annotated to Carbohydrate-Active enzymes, peptidases, secondary metabolites and virulence factors. DemaDb Genome Browser enables users to browse and visualize entire genomes with annotation data including gene prediction, structure, orientation and custom feature tracks. The Pathway Browser based on the KEGG pathway database allows users to look into molecular interaction and reaction networks for all KEGG annotated genes. The availability of downloadable files containing assembly, nucleic acid, as well as protein data allows the direct retrieval for further downstream works. DemaDb is a useful resource for fungal research community especially those involved in genome-scale analysis, functional genomics, genetics and disease studies of dematiaceous fungi. Database URL: http://fungaldb.um.edu.my.
  15. Yew SM, Chan CL, Kuan CS, Toh YF, Ngeow YF, Na SL, et al.
    BMC Genomics, 2016 Feb 03;17:91.
    PMID: 26842951 DOI: 10.1186/s12864-016-2409-8
    Ochroconis mirabilis, a recently introduced water-borne dematiaceous fungus, is occasionally isolated from human skin lesions and nails. We identified an isolate of O. mirabilis from a skin scraping with morphological and molecular studies. Its genome was then sequenced and analysed for genetic features related to classification and biological characteristics.
  16. Kuan CS, Cham CY, Singh G, Yew SM, Tan YC, Chong PS, et al.
    PLoS One, 2016;11(8):e0161008.
    PMID: 27570972 DOI: 10.1371/journal.pone.0161008
    Cladophialophora bantiana is a dematiaceous fungus with a predilection for causing central nervous system (CNS) infection manifesting as brain abscess in both immunocompetent and immunocompromised patients. In this paper, we report comprehensive genomic analyses of C. bantiana isolated from the brain abscess of an immunocompetent man, the first reported case in Malaysia and Southeast Asia. The identity of the fungus was determined using combined morphological analysis and multilocus phylogeny. The draft genome sequence of a neurotrophic fungus, C. bantiana UM 956 was generated using Illumina sequencing technology to dissect its genetic fundamental and basic biology. The assembled 37.1 Mb genome encodes 12,155 putative coding genes, of which, 1.01% are predicted transposable elements. Its genomic features support its saprophytic lifestyle, renowned for its versatility in decomposing hemicellulose and pectin components. The C. bantiana UM 956 was also found to carry some important putative genes that engaged in pathogenicity, iron uptake and homeostasis as well as adaptation to various stresses to enable the organism to survive in hostile microenvironment. This wealth of resource will further catalyse more downstream functional studies to provide better understanding on how this fungus can be a successful and persistent pathogen in human.
  17. Kuan CS, Yew SM, Toh YF, Chan CL, Ngeow YF, Lee KW, et al.
    DNA Res, 2015 Jun;22(3):219-32.
    PMID: 25922537 DOI: 10.1093/dnares/dsv007
    Bipolaris papendorfii has been reported as a fungal plant pathogen that rarely causes opportunistic infection in humans. Secondary metabolites isolated from this fungus possess medicinal and anticancer properties. However, its genetic fundamental and basic biology are largely unknown. In this study, we report the first draft genome sequence of B. papendorfii UM 226 isolated from the skin scraping of a patient. The assembled 33.4 Mb genome encodes 11,015 putative coding DNA sequences, of which, 2.49% are predicted transposable elements. Multilocus phylogenetic and phylogenomic analyses showed B. papendorfii UM 226 clustering with Curvularia species, apart from other plant pathogenic Bipolaris species. Its genomic features suggest that it is a heterothallic fungus with a putative unique gene encoding the LysM-containing protein which might be involved in fungal virulence on host plants, as well as a wide array of enzymes involved in carbohydrate metabolism, degradation of polysaccharides and lignin in the plant cell wall, secondary metabolite biosynthesis (including dimethylallyl tryptophan synthase, non-ribosomal peptide synthetase, polyketide synthase), the terpenoid pathway and the caffeine metabolism. This first genomic characterization of B. papendorfii provides the basis for further studies on its biology, pathogenicity and medicinal potential.
  18. Chin CY, Hara Y, Ghazali AK, Yap SJ, Kong C, Wong YC, et al.
    BMC Genomics, 2015;16:471.
    PMID: 26092034 DOI: 10.1186/s12864-015-1692-0
    Chronic bacterial infections occur as a result of the infecting pathogen's ability to live within a biofilm, hence escaping the detrimental effects of antibiotics and the immune defense system. Burkholderia pseudomallei, a gram-negative facultative pathogen, is distinctive in its ability to survive within phagocytic and non-phagocytic cells, to persist in vivo for many years and subsequently leading to relapse as well as the development of chronic disease. The capacity to persist has been attributed to the pathogen's ability to form biofilm. However, the underlying biology of B. pseudomallei biofilm development remains unresolved.
  19. Ghazali AK, Eng SA, Khoo JS, Teoh S, Hoh CC, Nathan S
    Microb Genom, 2021 02;7(2).
    PMID: 33565959 DOI: 10.1099/mgen.0.000527
    Burkholderia pseudomallei, a soil-dwelling Gram-negative bacterium, is the causative agent of the endemic tropical disease melioidosis. Clinical manifestations of B. pseudomallei infection range from acute or chronic localized infection in a single organ to fulminant septicaemia in multiple organs. The diverse clinical manifestations are attributed to various factors, including the genome plasticity across B. pseudomallei strains. We previously characterized B. pseudomallei strains isolated in Malaysia and noted different levels of virulence in model hosts. We hypothesized that the difference in virulence might be a result of variance at the genome level. In this study, we sequenced and assembled four Malaysian clinical B. pseudomallei isolates, UKMR15, UKMPMC2000, UKMD286 and UKMH10. Phylogenomic analysis showed that Malaysian subclades emerged from the Asian subclade, suggesting that the Malaysian strains originated from the Asian region. Interestingly, the low-virulence strain, UKMH10, was the most distantly related compared to the other Malaysian isolates. Genomic island (GI) prediction analysis identified a new island of 23 kb, GI9c, which is present in B. pseudomallei and Burkholderia mallei, but not Burkholderia thailandensis. Genes encoding known B. pseudomallei virulence factors were present across all four genomes, but comparative analysis of the total gene content across the Malaysian strains identified 104 genes that are absent in UKMH10. We propose that these genes may encode novel virulence factors, which may explain the reduced virulence of this strain. Further investigation on the identity and role of these 104 proteins may aid in understanding B. pseudomallei pathogenicity to guide the design of new therapeutics for treating melioidosis.
  20. Wong YC, Abd El Ghany M, Ghazzali RNM, Yap SJ, Hoh CC, Pain A, et al.
    Front Microbiol, 2018;9:1118.
    PMID: 29896180 DOI: 10.3389/fmicb.2018.01118
    A Burkholderia cenocepacia infection usually leads to reduced survival and fatal cepacia syndrome in cystic fibrosis patients. The identification of B. cenocepacia essential genes for in vivo survival is key to designing new anti-infectives therapies. We used the Transposon-Directed Insertion Sequencing (TraDIS) approach to identify genes required for B. cenocepacia survival in the model infection host, Caenorhabditis elegans. A B. cenocepacia J2315 transposon pool of ∼500,000 mutants was used to infect C. elegans. We identified 178 genes as crucial for B. cenocepacia survival in the infected nematode. The majority of these genes code for proteins of unknown function, many of which are encoded by the genomic island BcenGI13, while other gene products are involved in nutrient acquisition, general stress responses and LPS O-antigen biosynthesis. Deletion of the glycosyltransferase gene wbxB and a histone-like nucleoid structuring (H-NS) protein-encoding gene (BCAL0154) reduced bacterial accumulation and attenuated virulence in C. elegans. Further analysis using quantitative RT-PCR indicated that BCAL0154 modulates B. cenocepacia pathogenesis via transcriptional regulation of motility-associated genes including fliC, fliG, flhD, and cheB1. This screen has successfully identified genes required for B. cenocepacia survival within the host-associated environment, many of which are potential targets for developing new antimicrobials.
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