Displaying publications 41 - 60 of 173 in total

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  1. Gan HM, Ibrahim Z, Shahir S, Yahya A
    FEMS Microbiol Lett, 2011 May;318(2):108-14.
    PMID: 21323982 DOI: 10.1111/j.1574-6968.2011.02245.x
    Genes involved in the 4-aminobenzenesulfonate (4-ABS) degradation pathway of Hydrogenophaga sp. PBC were identified using transposon mutagenesis. The screening of 10,000 mutants for incomplete 4-ABS biotransformation identified four mutants with single transposon insertion. Genes with insertions that impaired the ability to utilize 4-ABS for growth included (1) 4-sulfocatechol 1,2-dioxygenase β-subunit (pcaH2) and 3-sulfomuconate cycloisomerase involved in the modified β-ketoadipate pathway; (2) 4-aminobenzenesulfonate 3,4-dioxygenase component (sadA) involved in aromatic ring hydroxylation; and (3) transposase gene homolog with a putative cis-diol dehydrogenase gene located downstream. The pcaH2 mutant strain accumulated brown metabolite during growth on 4-ABS which was identified as 4-sulfocatechol through thin layer chromatography and HPLC analyses. Supplementation of wild-type sadA gene in trans restored the 4-ABS degradation ability of the sadA mutant, thus supporting the annotation of its disrupted gene.
  2. Yaakop AS, Chan KG, Gan HM, Goh KM
    Genome Announc, 2015;3(5).
    PMID: 26494670 DOI: 10.1128/genomeA.01224-15
    Jeotgalibacillus alimentarius JY-13(T) (=KCCM 80002(T) = JCM 10872(T)) is a moderate halophile. In 2001, this was the first strain of the newly proposed Jeotgalibacillus genus. The draft genome of J. alimentarius was found to consist of 32 contigs (N50, 315,125 bp) with a total size of 3,364,745 bp. This genome information will be helpful for studies on pigmentation as well as applications for this bacterium.
  3. Lai WX, Gan HM, Hudson AO, Savka MA
    Genome Announc, 2016;4(1).
    PMID: 26847900 DOI: 10.1128/genomeA.01695-15
    The whole-genome sequence of a new genospecies of Methylobacterium sp., named GXS13 and isolated from grapevine xylem sap, is reported and demonstrates potential for methylotrophy, cytokinin synthesis, and cell wall modification. In addition, biosynthetic gene clusters were identified for cupriachelin, carotenoid, and acyl-homoserine lactone using the antiSMASH server.
  4. Harrisson K, Pavlova A, Gan HM, Lee YP, Austin CM, Sunnucks P
    Heredity (Edinb), 2016 Jun;116(6):506-15.
    PMID: 26883183 DOI: 10.1038/hdy.2016.8
    Climatic differences across a taxon's range may be associated with specific bioenergetic demands and may result in genetics-based metabolic adaptation, particularly in aquatic ectothermic organisms that rely on heat exchange with the environment to regulate key physiological processes. Extending down the east coast of Australia, the Great Dividing Range (GDR) has a strong influence on climate and the evolutionary history of freshwater fish species. Despite the GDR acting as a strong contemporary barrier to fish movement, many species, and species with shared ancestries, are found on both sides of the GDR, indicative of historical dispersal events. We sequenced complete mitogenomes from the four extant species of the freshwater cod genus Maccullochella, two of which occur on the semi-arid, inland side of the GDR, and two on the mesic coastal side. We constructed a dated phylogeny and explored the relative influences of purifying and positive selection in the evolution of mitogenome divergence among species. Results supported mid- to late-Pleistocene divergence of Maccullochella across the GDR (220-710 thousand years ago), bringing forward previously reported dates. Against a background of pervasive purifying selection, we detected potentially functionally relevant fixed amino acid differences across the GDR. Although many amino acid differences between inland and coastal species may have become fixed under relaxed purifying selection in coastal environments rather than positive selection, there was evidence of episodic positive selection acting on specific codons in the Mary River coastal lineage, which has consistently experienced the warmest and least extreme climate in the genus.
  5. Yaakop AS, Chan KG, Gan HM, Goh KM
    Mar Genomics, 2015 Oct;23:59-60.
    PMID: 25999308 DOI: 10.1016/j.margen.2015.05.004
    Jeotgalibacillus campisalis SF-57(T) (=KCCM 41644(T), JCM 11810(T)) is a moderate halophilic bacterium isolated from a Korean marine saltern. In this study, we describe the high-quality draft genome of strain SF-57(T), which was assembled into 24 contigs containing 3,650,490bp with a G+C content of 41.06%. Availability of the genome sequence of J. campisalis SF-57(T) will contribute to a better understanding of the genus Jeotgalibacillus.
  6. Watts MP, Spurr LP, Gan HM, Moreau JW
    Appl Microbiol Biotechnol, 2017 Jul;101(14):5889-5901.
    PMID: 28510801 DOI: 10.1007/s00253-017-8313-6
    Thiocyanate (SCN-) forms as a by-product of cyanidation during gold ore processing and can be degraded by a variety of microorganisms utilizing it as an energy, nitrogen, sulphur and/or carbon source. In complex consortia inhabiting bioreactor systems, a range of metabolisms are sustained by SCN- degradation; however, despite the addition or presence of labile carbon sources in most bioreactor designs to date, autotrophic bacteria have been found to dominate key metabolic functions. In this study, we cultured an autotrophic SCN--degrading consortium directly from gold mine tailings. In a batch-mode bioreactor experiment, this consortium degraded 22 mM SCN-, accumulating ammonium (NH4+) and sulphate (SO42-) as the major end products. The consortium consisted of a diverse microbial community comprised of chemolithoautotrophic members, and despite the absence of an added organic carbon substrate, a significant population of heterotrophic bacteria. The role of eukaryotes in bioreactor systems is often poorly understood; however, we found their 18S rRNA genes to be most closely related to sequences from bacterivorous Amoebozoa. Through combined chemical and phylogenetic analyses, we were able to infer roles for key microbial consortium members during SCN- biodegradation. This study provides a basis for understanding the behaviour of a SCN- degrading bioreactor under autotrophic conditions, an anticipated approach to remediating SCN- at contemporary gold mines.
  7. Gan HM, Lee MVL, Savka MA
    PeerJ, 2019;7:e6366.
    PMID: 30775173 DOI: 10.7717/peerj.6366
    The reported Agrobacterium radiobacter DSM 30174T genome is highly fragmented, hindering robust comparative genomics and genome-based taxonomic analysis. We re-sequenced the Agrobacterium radiobacter type strain, generating a dramatically improved genome with high contiguity. In addition, we sequenced the genome of Agrobacterium tumefaciens B6T, enabling for the first time, a proper comparative genomics of these contentious Agrobacterium species. We provide concrete evidence that the previously reported Agrobacterium radiobacter type strain genome (Accession Number: ASXY01) is contaminated which explains its abnormally large genome size and fragmented assembly. We propose that Agrobacterium tumefaciens be reclassified as Agrobacterium radiobacter subsp. tumefaciens and that Agrobacterium radiobacter retains it species status with the proposed name of Agrobacterium radiobacter subsp. radiobacter. This proposal is based, first on the high pairwise genome-scale average nucleotide identity supporting the amalgamation of both Agrobacterium radiobacter and Agrobacterium tumefaciens into a single species. Second, maximum likelihood tree construction based on the concatenated alignment of shared genes (core genes) among related strains indicates that Agrobacterium radiobacter NCPPB3001 is sufficiently divergent from Agrobacterium tumefaciens to propose two independent sub-clades. Third, Agrobacterium tumefaciens demonstrates the genomic potential to synthesize the L configuration of fucose in its lipid polysaccharide, fostering its ability to colonize plant cells more effectively than Agrobacterium radiobacter.
  8. Chen JW, Gan HM, Yin WF, Chan KG
    J Bacteriol, 2012 Dec;194(23):6681-2.
    PMID: 23144419 DOI: 10.1128/JB.01866-12
    Roseomonas sp. strain B5 was isolated from Malaysian tropical soil that showed N-acylhomoserine lactone degradation. This is the first genome announcement of a member from the genus of Roseomonas and the first report on the quorum-quenching activity of Roseomonas spp.
  9. Chan GF, Gan HM, Rashid NA
    J Bacteriol, 2012 Oct;194(20):5716-7.
    PMID: 23012290
    Enterococcus sp. strain C1 is a facultative anaerobe which was coisolated with Citrobacter sp. strain A1 from a sewage oxidation pond. Strain C1 could degrade azo dyes very efficiently via azo reduction and desulfonation in a microaerophilic environment. Here the draft genome sequence of Enterococcus sp. C1 is reported.
  10. Chan GF, Gan HM, Rashid NA
    J Bacteriol, 2012 Oct;194(19):5485-6.
    PMID: 22965102 DOI: 10.1128/JB.01285-12
    Citrobacter sp. strain A1, isolated from a sewage oxidation pond, is a facultative aerobe and mesophilic dye-degrading bacterium. This organism degrades azo dyes efficiently via azo reduction and desulfonation, followed by the successive biotransformation of dye intermediates under an aerobic environment. Here we report the draft genome sequence of Citrobacter sp. A1.
  11. Gan HM, Chew TH, Hudson AO, Savka MA
    J Bacteriol, 2012 Sep;194(18):5157-8.
    PMID: 22933776 DOI: 10.1128/JB.01201-12
    Methylobacterium sp. strain GXF4 is an isolate from grapevine. Here we present the sequence, assembly, and annotation of its genome, which may shed light on its role as a grapevine xylem inhabitant. To our knowledge, this is the first genome announcement of a plant xylem-associated strain of the genus Methylobacterium.
  12. Gan HM, Chew TH, Hudson AO, Savka MA
    J Bacteriol, 2012 Sep;194(18):5137-8.
    PMID: 22933764 DOI: 10.1128/JB.01159-12
    Novosphingobium sp. strain Rr 2-17 is an N-acyl homoserine lactone (AHL)-producing bacterium isolated from the crown gall tumor of a grapevine. To our knowledge, this is the first draft genome announcement of a plant-associated strain from the genus Novosphingobium.
  13. Ooi MK, Gan HM, Rohani A, Syed Hassan S
    Genome Announc, 2016;4(4).
    PMID: 27563048 DOI: 10.1128/genomeA.00876-16
    Here, we report the complete genome sequence of a chikungunya virus coinfection strain isolated from a dengue virus serotype 2-infected patient in Malaysia. This coinfection strain was determined to be of the Asian genotype and contains a novel insertion in the nsP3 gene.
  14. Wilson JJ, Brandon-Mong GJ, Gan HM, Sing KW
    PMID: 29591722 DOI: 10.1080/24701394.2018.1455189
    Consensus on the optimal high-throughput sequencing (HTS) approach to examine biodiversity in mixed terrestrial arthropod samples has not been reached. Metatranscriptomics could increase the proportion of taxonomically informative mitochondrial reads in HTS outputs but has not been investigated for terrestrial arthropod samples. We compared the efficiency of 16S rRNA metabarcoding, metagenomics and metatranscriptomics for detecting species in a mixed terrestrial arthropod sample (pooled DNA/RNA from 38 taxa). 16S rRNA metabarcoding and nuclear rRNA-depleted metatranscriptomics had the highest detection rate with 97% of input species detected. Based on cytochrome c oxidase I, metagenomics had the highest detection rate with 82% of input species detected, but metatranscriptomics produced a larger proportion of reads matching (Sanger) reference sequences. Metatranscriptomics with nuclear rRNA depletion may offer advantages over metabarcoding through reducing the number of spurious operational taxonomic units while retaining high detection rates, and offers natural enrichment of mitochondrial sequences which may enable increased species detection rates compared with metagenomics.
  15. Lee PS, Gan HM, Clements GR, Wilson JJ
    Genome, 2016 May 11.
    PMID: 27696907
    Mammal diversity assessments based on DNA derived from invertebrates have been suggested as alternatives to assessments based on traditional methods; however, no study has field-tested both approaches simultaneously. In Peninsular Malaysia, we calibrated the performance of mammal DNA derived from blowflies (Diptera: Calliphoridae) against traditional methods used to detect species. We first compared five methods (cage trapping, mist netting, hair trapping, scat collection, and blowfly-derived DNA) in a forest reserve with no recent reports of megafauna. Blowfly-derived DNA and mist netting detected the joint highest number of species (n = 6). Only one species was detected by multiple methods. Compared to the other methods, blowfly-derived DNA detected both volant and non-volant species. In another forest reserve, rich in megafauna, we calibrated blowfly-derived DNA against camera traps. Blowfly-derived DNA detected more species (n = 11) than camera traps (n = 9), with only one species detected by both methods. The rarefaction curve indicated that blowfly-derived DNA would continue to detect more species with greater sampling effort. With further calibration, blowfly-derived DNA may join the list of traditional field methods. Areas for further investigation include blowfly feeding and dispersal biology, primer biases, and the assembly of a comprehensive and taxonomically-consistent DNA barcode reference library.
  16. Lau MML, Lim LWK, Chung HH, Gan HM
    Data Brief, 2021 Dec;39:107481.
    PMID: 34712757 DOI: 10.1016/j.dib.2021.107481
    The Javan mahseer (Tor tambra) is one of the most valuable freshwater fish found in Tor species. To date, other than mitogenomic data (BioProject: PRJNA422829), genomic and transcriptomic resources for this species are still lacking which is crucial to understand the molecular mechanisms associated with important traits such as growth, immune response, reproduction and sex determination. For the first time, we sequenced the transcriptome from a whole juvenile fish using Illumina NovaSEQ6000 generating raw paired-end reads. De novo transcriptome assembly generated a draft transcriptome (BUSCO5 completeness of 91.2% [Actinopterygii_odb10 database]) consisting of 259,403 putative transcripts with a total and N50 length of 333,881,215 bp and 2283 bp, respectively. A total count of 77,503 non-redundant protein coding sequences were predicted from the transcripts and used for functional annotation. We mapped the predicted proteins to 304 known KEGG pathways with signal transduction cluster having the highest representation followed by immune system and endocrine system. In addition, transcripts exhibiting significant similarity to previously published growth-and immune-related genes were identified which will facilitate future molecular breeding of Tor tambra.
  17. Austin CM, Croft LJ, Grandjean F, Gan HM
    Front Genet, 2021;12:695763.
    PMID: 35126445 DOI: 10.3389/fgene.2021.695763
    Cherax destructor, the yabby, is an iconic Australian freshwater crayfish species, which, similar to other major invertebrate groups, is grossly under-represented in genomic databases. The yabby is also the principal commercial freshwater crustacean species in Australia subject to explotation via inland fisheries and aquaculture. To address the genomics knowledge gap for this species and explore cost effective and efficient methods for genome assembly, we generated 106.8 gb of Nanopore reads and performed a long-read only assembly of the Cherax destructor genome. On a mini-server configured with an ultra-fast swap space, the de novo assembly took 131 h (∼5.5 days). Genome polishing with 126.3 gb of PCR-Free Illumina reads generated an assembled genome size of 3.3 gb (74.6% BUSCO completeness) with a contig N50 of 80,900 bp, making it the most contiguous for freshwater crayfish genome assemblies. We found an unusually large number of cellulase genes within the yabby genome which is relevant to understanding the nutritional biology, commercial feed development, and ecological role of this species and crayfish more generally. These resources will be useful for genomic research on freshwater crayfish and our methods for rapid and super-efficient genome assembly will have wide application.
  18. Gan HM, Lee MVJ, Savka MA
    Microbiol Resour Announc, 2018 Sep;7(9).
    PMID: 30533933 DOI: 10.1128/MRA.01045-18
    Using Illumina and Nanopore reads, we assembled a high-quality draft genome sequence of Allorhizobium vitis K309T (= ATCC 49767T, = NCPPB 3554T), a phytopathogenic strain isolated from a grapevine in Australia. The hybrid approach generated 50% fewer contigs and a 3-fold increase in the N 50 value compared with the previous Illumina-only assembly.
  19. Gan HM, Grandjean F, Jenkins TL, Austin CM
    BMC Genomics, 2019 May 03;20(1):335.
    PMID: 31053062 DOI: 10.1186/s12864-019-5704-3
    BACKGROUND: The recently published complete mitogenome of the European lobster (Homarus gammarus) that was generated using long-range PCR exhibits unusual gene composition (missing nad2) and gene rearrangements among decapod crustaceans with strong implications in crustacean phylogenetics. Such atypical mitochondrial features will benefit greatly from validation with emerging long read sequencing technologies such as Oxford Nanopore that can more accurately identify structural variation.

    RESULTS: We re-sequenced the H. gammarus mitogenome on an Oxford Nanopore Minion flowcell and performed a long-read only assembly, generating a complete mitogenome assembly for H. gammarus. In contrast to previous reporting, we found an intact mitochondrial nad2 gene in the H. gammarus mitogenome and showed that its gene organization is broadly similar to that of the American lobster (H. americanus) except for the presence of a large tandemly duplicated region with evidence of pseudogenization in one of each duplicated protein-coding genes.

    CONCLUSIONS: Using the European lobster as an example, we demonstrate the value of Oxford Nanopore long read technology in resolving problematic mitogenome assemblies. The increasing accessibility of Oxford Nanopore technology will make it an attractive and useful tool for evolutionary biologists to verify new and existing unusual mitochondrial gene rearrangements recovered using first and second generation sequencing technologies, particularly those used to make phylogenetic inferences of evolutionary scenarios.

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