Displaying publications 1 - 20 of 62 in total

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  1. Bhat R, Goh KM
    Food Chem, 2017 Jan 15;215:470-6.
    PMID: 27542500 DOI: 10.1016/j.foodchem.2016.07.160
    Hand-pressed strawberry juice samples were subjected to sonication treatments (0, 15 and 30min at 20°C, 25kHz frequency). Physicochemical properties (°Brix, pH, water activity, viscosity, titratable acidity, cloud assessment and turbidity), antioxidant compounds and activity (total phenolics, ascorbic acid, anthocyanins, free radical scavenging activity), polyphenoloxidase enzyme activity, browning degree and microbial load were evaluated. Results showed non-significant changes for °Brix, pH, water activity, titratable acidity and colour parameters in sonicated samples compared to control (0min). Sonication treatments resulted in reduced viscosity and increased cloudiness and turbidity. Overall, treatment for 30min showed significant enhancement in bioactive compounds under study. Besides, sonication treatment imparted non-significant changes in polyphenoloxidase activity and in browning degree. However, sonication was incompetent in reducing microbial load. Results generated from this study were encouraging and this is expected to provide platform for future commercial applications on a pilot scale.
  2. Goh PH, Illias RM, Goh KM
    Int J Mol Sci, 2012;13(5):5307-23.
    PMID: 22754298 DOI: 10.3390/ijms13055307
    Studies related to the engineering of calcium binding sites of CGTase are limited. The calcium binding regions that are known for thermostability function were subjected to site-directed mutagenesis in this study. The starting gene-protein is a variant of CGTase Bacillus sp. G1, reported earlier and denoted as "parent CGTase" herein. Four CGTase variants (S182G, S182E, N132R and N28R) were constructed. The two variants with a mutation at residue 182, located adjacent to the Ca-I site and the active site cleft, possessed an enhanced thermostability characteristic. The activity half-life of variant S182G at 60 °C was increased to 94 min, while the parent CGTase was only 22 min. This improvement may be attributed to the formation of a shorter α-helix and the alleviation of unfavorable steric strains by glycine at the corresponding region. For the variant S182E, an extra ionic interaction at the A/B domain interface increased the half-life to 31 min, yet it reduced CGTase activity. The introduction of an ionic interaction at the Ca-I site via the mutation N132R disrupted CGTase catalytic activity. Conversely, the variant N28R, which has an additional ionic interaction at the Ca-II site, displayed increased cyclization activity. However, thermostability was not affected.
  3. Goh KM, Dickinson M, Supramaniam CV
    Physiol Plant, 2018 Mar;162(3):274-289.
    PMID: 28940509 DOI: 10.1111/ppl.12645
    Lignification of the plant cell wall could serve as the first line of defense against pathogen attack, but the molecular mechanisms of virulence and disease between oil palm and Ganoderma boninense are poorly understood. This study presents the biochemical, histochemical, enzymology and gene expression evidences of enhanced lignin biosynthesis in young oil palm as a response to G. boninense (GBLS strain). Comparative studies with control (T1), wounded (T2) and infected (T3) oil palm plantlets showed significant accumulation of total lignin content and monolignol derivatives (syringaldehyde and vanillin). These derivatives were deposited on the epidermal cell wall of infected plants. Moreover, substantial differences were detected in the activities of enzyme and relative expressions of genes encoding phenylalanine ammonia lyase (EC 4.3.1.24), cinnamate 4-hydroxylase (EC 1.14.13.11), caffeic acid O-methyltransferase (EC 2.1.1.68) and cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195). These enzymes are key intermediates dedicated to the biosynthesis of lignin monomers, the guaicyl (G), syringyl (S) and ρ-hydroxyphenyl (H) subunits. Results confirmed an early, biphasic and transient positive induction of all gene intermediates, except for CAD enzyme activities. These differences were visualized by anatomical and metabolic changes in the profile of lignin in the oil palm plantlets such as low G lignin, indicating a potential mechanism for enhanced susceptibility toward G. boninense infection.
  4. 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.
  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. Goh KM, Liew KJ, Chai KP, Illias RM
    Methods Mol Biol, 2017;1498:385-396.
    PMID: 27709591
    Protein engineering is a very useful tool for probing structure-function relationships in proteins. Specifically, site-directed mutagenized proteins can provide useful insights into structural, binding and catalytic mechanisms of a protein, particularly when coupled with crystallization. In this chapter, we describe two protocols for performing site-directed mutagenesis of any protein-coding sequence, namely, megaprimer PCR and overlapping extension PCR (OE-PCR). We use as an example how these two SDM methods enhanced the function of a cyclodextrin glucosyltransferase (CGTase) from Bacillus lehensis strain G1.
  7. Goh KM, Lai OM, Abas F, Tan CP
    Food Chem, 2017 Jan 15;215:200-8.
    PMID: 27542468 DOI: 10.1016/j.foodchem.2016.07.146
    Soy sauce fermentation was simulated in a laboratory and subjected to 10min of sonication. A full factorial design, including different cycles, probe size, and amplitude was used. The composition of 17 free-amino acids (FAAs) was determined by the AccQ-Tag method with fluorescent detection. Main effect plots showed total FAAs extraction was favoured under continuous sonication at 100% amplitude using a 14mm diameter transducer probe, reaching 1214.2±64.3mg/100ml of total FAAs. Moreover, after 7days of fermentation, sonication treatment caused significantly higher levels (p<0.05) of glutamic acids (343.0±22.09mg/100g), total FAAs (1720.0±70.6mg/100g), and essential FAAs (776.3±7.0mg/100g) 3days sooner than the control. Meanwhile, enzymatic and microbial behaviours remained undisturbed. Collectively, the sonication to moromi resulted in maturation 57% faster than the untreated control.
  8. Kahar UM, Sani MH, Chan KG, Goh KM
    Molecules, 2016 Sep 09;21(9).
    PMID: 27618002 DOI: 10.3390/molecules21091196
    α-Amylase from Anoxybacillus sp. SK3-4 (ASKA) is a thermostable enzyme that produces a high level of maltose from starches. A truncated ASKA (TASKA) variant with improved expression and purification efficiency was characterized in an earlier study. In this work, TASKA was purified and immobilized through covalent attachment on three epoxide (ReliZyme EP403/M, Immobead IB-150P, and Immobead IB-150A) and an amino-epoxide (ReliZyme HFA403/M) activated supports. Several parameters affecting immobilization were analyzed, including the pH, temperature, and quantity (mg) of enzyme added per gram of support. The influence of the carrier surface properties, pore sizes, and lengths of spacer arms (functional groups) on biocatalyst performances were studied. Free and immobilized TASKAs were stable at pH 6.0-9.0 and active at pH 8.0. The enzyme showed optimal activity and considerable stability at 60 °C. Immobilized TASKA retained 50% of its initial activity after 5-12 cycles of reuse. Upon degradation of starches and amylose, only immobilized TASKA on ReliZyme HFA403/M has comparable hydrolytic ability with the free enzyme. To the best of our knowledge, this is the first report of an immobilization study of an α-amylase from Anoxybacillus spp. and the first report of α-amylase immobilization using ReliZyme and Immobeads as supports.
  9. Kahar UM, Ng CL, Chan KG, Goh KM
    Appl Microbiol Biotechnol, 2016 Jul;100(14):6291-307.
    PMID: 27000839 DOI: 10.1007/s00253-016-7451-6
    Type I pullulanases are enzymes that specifically hydrolyse α-1,6 linkages in polysaccharides. This study reports the analyses of a novel type I pullulanase (PulASK) from Anoxybacillus sp. SK3-4. Purified PulASK (molecular mass of 80 kDa) was stable at pH 5.0-6.0 and was most active at pH 6.0. The optimum temperature for PulASK was 60 °C, and the enzyme was reasonably stable at this temperature. Pullulan was the preferred substrate for PulASK, with 89.90 % adsorbance efficiency (various other starches, 56.26-72.93 % efficiency). Similar to other type I pullulanases, maltotriose was formed on digestion of pullulan by PulASK. PulASK also reacted with β-limit dextrin, a sugar rich in short branches, and formed maltotriose, maltotetraose and maltopentaose. Nevertheless, PulASK was found to preferably debranch long branches at α-1,6 glycosidic bonds of starch, producing amylose, linear or branched oligosaccharides, but was nonreactive against short branches; thus, no reducing sugars were detected. This is surprising as all currently known type I pullulanases produce reducing sugars (predominantly maltotriose) on digesting starch. The closest homologue of PulASK (95 % identity) is a type I pullulanase from Anoxybacillus sp. LM14-2 (Pul-LM14-2), which is capable of forming reducing sugars from starch. With rational design, amino acids 362-370 of PulASK were replaced with the corresponding sequence of Pul-LM14-2. The mutant enzyme formed reducing sugars on digesting starch. Thus, we identified a novel motif involved in substrate specificity in type I pullulanases. Our characterization may pave the way for the industrial application of this unique enzyme.
  10. Wang J, Goh KM, Salem DR, Sani RK
    Sci Rep, 2019 02 07;9(1):1608.
    PMID: 30733471 DOI: 10.1038/s41598-018-36983-z
    Geobacillus sp. WSUCF1 is a Gram-positive, spore-forming, aerobic and thermophilic bacterium, isolated from a soil sample obtained from a compost facility. Strain WSUCF1 demonstrated EPS producing capability using different sugars as the carbon source. The whole-genome analysis of WSUCF1 was performed to disclose the essential genes correlated with nucleotide sugar precursor biosynthesis, assembly of monosaccharide units, export of the polysaccharide chain, and regulation of EPS production. Both the biosynthesis pathway and export mechanism of EPS were proposed based on functional annotation. Additionally, the genome description of strain WSUCF1 suggests sophisticated systems for its adaptation under thermophilic conditions. The presence of genes associated with CRISPR-Cas system, quorum quenching lactonase, polyketide synthesis and arsenic resistance makes this strain a potential candidate for various applications in biotechnology and biomedicine. The present study indicates that strain WSUCF1 has promise as a thermophilic EPS producer for a broad range of industrial applications. To the best of our knowledge, this is the first report on genome analysis of a thermophilic Geobacillus species focusing on its EPS biosynthesis and transportation, which will likely pave the way for both enhanced yield and tailor-made EPS production by thermophilic bacteria.
  11. Liew KJ, Teo SC, Shamsir MS, Goh KM
    Microbiol Resour Announc, 2019 Nov 14;8(46).
    PMID: 31727717 DOI: 10.1128/MRA.01238-19
    Longimonas halophila and Longibacter salinarum are type strains of underexplored genera affiliated with Salisaetaceae Herein, we report the draft genome sequences of two strains of these bacteria, L. halophila KCTC 42399 and L. salinarum KCTC 52045, with the intent of broadening knowledge of this family. Genome annotation and gene mining revealed that both bacteria exhibit amylolytic abilities.
  12. 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.
  13. 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).
  14. Ranjani V, Janeček S, Chai KP, Shahir S, Abdul Rahman RN, Chan KG, et al.
    Sci Rep, 2014 Jul 28;4:5850.
    PMID: 25069018 DOI: 10.1038/srep05850
    The α-amylases from Anoxybacillus species (ASKA and ADTA), Bacillus aquimaris (BaqA) and Geobacillus thermoleovorans (GTA, Pizzo and GtamyII) were proposed as a novel group of the α-amylase family GH13. An ASKA yielding a high percentage of maltose upon its reaction on starch was chosen as a model to study the residues responsible for the biochemical properties. Four residues from conserved sequence regions (CSRs) were thus selected, and the mutants F113V (CSR-I), Y187F and L189I (CSR-II) and A161D (CSR-V) were characterised. Few changes in the optimum reaction temperature and pH were observed for all mutants. Whereas the Y187F (t1/2 43 h) and L189I (t1/2 36 h) mutants had a lower thermostability at 65°C than the native ASKA (t1/2 48 h), the mutants F113V and A161D exhibited an improved t1/2 of 51 h and 53 h, respectively. Among the mutants, only the A161D had a specific activity, k(cat) and k(cat)/K(m) higher (1.23-, 1.17- and 2.88-times, respectively) than the values determined for the ASKA. The replacement of the Ala-161 in the CSR-V with an aspartic acid also caused a significant reduction in the ratio of maltose formed. This finding suggests the Ala-161 may contribute to the high maltose production of the ASKA.
  15. Kahar UM, Chan KG, Salleh MM, Hii SM, Goh KM
    Int J Mol Sci, 2013;14(6):11302-18.
    PMID: 23759984 DOI: 10.3390/ijms140611302
    An amylopullulanase of the thermophilic Anoxybacillus sp. SK3-4 (ApuASK) was purified to homogeneity and characterized. Though amylopullulanases larger than 200 kDa are rare, the molecular mass of purified ApuASK appears to be approximately 225 kDa, on both SDS-PAGE analyses and native-PAGE analyses. ApuASK was stable between pH 6.0 and pH 8.0 and exhibited optimal activity at pH 7.5. The optimal temperature for ApuASK enzyme activity was 60 °C, and it retained 54% of its total activity for 240 min at 65 °C. ApuASK reacts with pullulan, starch, glycogen, and dextrin, yielding glucose, maltose, and maltotriose. Interestingly, most of the previously described amylopullulanases are unable to produce glucose and maltose from these substrates. Thus, ApuASK is a novel, high molecular-mass amylopullulanase able to produce glucose, maltose, and maltotriose from pullulan and starch. Based on whole genome sequencing data, ApuASK appeared to be the largest protein present in Anoxybacillus sp. SK3-4. The α-amylase catalytic domain present in all of the amylase superfamily members is present in ApuASK, located between the cyclodextrin (CD)-pullulan-degrading N-terminus and the α-amylase catalytic C-terminus (amyC) domains. In addition, the existence of a S-layer homology (SLH) domain indicates that ApuASK might function as a cell-anchoring enzyme and be important for carbohydrate utilization in a streaming hot spring.
  16. Chai YY, Kahar UM, Md Salleh M, Md Illias R, Goh KM
    Environ Technol, 2012 Jun;33(10-12):1231-8.
    PMID: 22856294
    Two thermophilic bacteria (SK3-4 and DT3-1) were isolated from the Sungai Klah (SK) and Dusun Tua (DT) hot springs in Malaysia. The cells from both strains were rod-shaped, stained Gram positive and formed endospores. The optimal growth of both strains was observed at 55 degrees C and pH 7. Strain DT3-1 exhibited a higher tolerance to chloramphenicol (100 microg ml(-1)) but showed a lower tolerance to sodium chloride (2%, w/v) compared to strain SK3-4. Phylogenetic analysis based on 16S rRNA gene sequences revealed that both strains belong to the genus Anoxybacillus. High concentrations of 15:0 iso in the fatty acid profiles support the conclusion that both strains belong to the genus Anoxybacillus and exhibit unique fatty acid compositions and percentages compared to other Anoxybacillus species. The DNA G + C contents were 42.0 mol% and 41.8 mol% for strains SK3-4 and DT3-1, respectively. Strains SK3-4 and DT3-1 were able to degrade pullulan and to produce maltotriose and glucose, respectively, as their main end products. Based on phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequences, and the DNA G + C content, we propose that strains SK3-4 and DT3-1 are new pullulan-degrading Anoxybacillus strains.
  17. Belduz AO, Canakci S, Chan KG, Kahar UM, Chan CS, Yaakop AS, et al.
    Stand Genomic Sci, 2015;10:70.
    PMID: 26413199 DOI: 10.1186/s40793-015-0065-2
    Species of Anoxybacillus are thermophiles and, therefore, their enzymes are suitable for many biotechnological applications. Anoxybacillus ayderensis AB04(T) (= NCIMB 13972(T) = NCCB 100050(T)) was isolated from the Ayder hot spring in Rize, Turkey, and is one of the earliest described Anoxybacillus type strains. The present work reports the cellular features of A. ayderensis AB04(T), together with a high-quality draft genome sequence and its annotation. The genome is 2,832,347 bp long (74 contigs) and contains 2,895 protein-coding sequences and 103 RNA genes including 14 rRNAs, 88 tRNAs, and 1 tmRNA. Based on the genome annotation of strain AB04(T), we identified genes encoding various glycoside hydrolases that are important for carbohydrate-related industries, which we compared with those of other, sequenced Anoxybacillus spp. Insights into under-explored industrially applicable enzymes and the possible applications of strain AB04(T) were also described.
  18. 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.
  19. Poli A, Nicolaus B, Chan KG, Kahar UM, Chan CS, Goh KM
    Genome Announc, 2015;3(3).
    PMID: 25999577 DOI: 10.1128/genomeA.00490-15
    Anoxybacillus thermarum AF/04(T) was isolated from the Euganean hot springs in Abano Terme, Italy. The present work reports a high-quality draft genome sequence of strain AF/04(T). This work also provides useful insights into glycoside hydrolases, glycoside transferases, and sugar transporters that may be involved in cellular carbohydrate metabolism.
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