Displaying publications 21 - 35 of 35 in total

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  1. Dinarvand M, Rezaee M, Foroughi M
    Braz J Microbiol, 2017 Jul-Sep;48(3):427-441.
    PMID: 28359854 DOI: 10.1016/j.bjm.2016.10.026
    The aim of this study was obtain a model that maximizes growth and production of inulinase and invertase by Aspergillus niger ATCC 20611, employing response surface methodology (RSM). The RSM with a five-variable and three-level central composite design (CCD) was employed to optimize the medium composition. Results showed that the experimental data could be appropriately fitted into a second-order polynomial model with a coefficient of determination (R2) more than 0.90 for all responses. This model adequately explained the data variation and represented the actual relationships between the parameters and responses. The pH and temperature value of the cultivation medium were the most significant variables and the effects of inoculum size and agitation speed were slightly lower. The intra-extracellular inulinase, invertase production and biomass content increased 10-32 fold in the optimized medium condition (pH 6.5, temperature 30°C, 6% (v/v), inoculum size and 150rpm agitation speed) by RSM compared with medium optimized through the one-factor-at-a-time method. The process development and intensification for simultaneous production of intra-extracellular inulinase (exo and endo inulinase) and invertase from A. niger could be used for industrial applications.
    Matched MeSH terms: Glycoside Hydrolases/genetics
  2. Jamek SB, Nyffenegger C, Muschiol J, Holck J, Meyer AS, Mikkelsen JD
    Appl Microbiol Biotechnol, 2017 Jun;101(11):4533-4546.
    PMID: 28280871 DOI: 10.1007/s00253-017-8198-4
    Type A chitinases (EC 3.2.1.14), GH family 18, attack chitin ((1 → 4)-2-acetamido-2-deoxy-β-D-glucan) and chito-oligosaccharides from the reducing end to catalyze release of chitobiose (N,N'-diacetylchitobiose) via hydrolytic cleavage of N-acetyl-β-D-glucosaminide (1 → 4)-β-linkages and are thus "exo-chitobiose hydrolases." In this study, the chitinase type A from Serratia marcescens (SmaChiA) was used as a template for identifying two novel exo-chitobiose hydrolase type A enzymes, FbalChi18A and MvarChi18A, originating from the marine organisms Ferrimonas balearica and Microbulbifer variabilis, respectively. Both FbalChi18A and MvarChi18A were recombinantly expressed in Escherichia coli and were confirmed to exert exo-chitobiose hydrolase activity on chito-oligosaccharides, but differed in temperature and pH activity response profiles. Amino acid sequence comparison of the catalytic β/α barrel domain of each of the new enzymes showed individual differences, but ~69% identity of each to that of SmaChiA and highly conserved active site residues. Superposition of a model substrate on 3D structural models of the catalytic domain of the enzymes corroborated exo-chitobiose hydrolase type A activity for FbalChi18A and MvarChi18A, i.e., substrate attack from the reducing end. A main feature of both of the new enzymes was the presence of C-terminal 5/12 type carbohydrate-binding modules (SmaChiA has no C-terminal carbohydrate binding module). These new enzymes may be useful tools for utilization of chitin as an N-acetylglucosamine donor substrate via chitobiose.
    Matched MeSH terms: Hydrolases/genetics*
  3. Furusawa G, Lau NS, Suganthi A, Amirul AA
    Microbiologyopen, 2017 02;6(1).
    PMID: 27987272 DOI: 10.1002/mbo3.405
    The agarolytic bacterium Persicobacter sp. CCB-QB2 was isolated from seaweed (genus Ulva) collected from a coastal area of Malaysia. Here, we report a high-quality draft genome sequence for QB2. The Rapid Annotation using Subsystem Technology (RAST) annotation server identified four β-agarases (PdAgaA, PdAgaB, PdAgaC, and PdAgaD) as well as galK, galE, and phosphoglucomutase, which are related to the Leloir pathway. Interestingly, QB2 exhibited a diauxic growth in the presence of two kinds of nutrients, such as tryptone and agar. In cells grown with agar, the profiles of agarase activity and growth rate were very similar. galK, galE, and phosphoglucomutase genes were highly expressed in the second growth phase of diauxic growth, indicating that QB2 cells use galactose hydrolyzed from agar by its agarases and exhibit nutrient prioritization. This is the first report describing diauxic growth for agarolytic bacteria. QB2 is a potential novel model organism for studying diauxic growth in environmental bacteria.
    Matched MeSH terms: Glycoside Hydrolases/genetics*
  4. Chin IS, Abdul Murad AM, Mahadi NM, Nathan S, Abu Bakar FD
    Protein Eng. Des. Sel., 2013 May;26(5):369-75.
    PMID: 23468570 DOI: 10.1093/protein/gzt007
    Cutinase has been ascertained as a biocatalyst for biotechnological and industrial bioprocesses. The Glomerella cingulata cutinase was genetically modified to enhance its enzymatic performance to fulfill industrial requirements. Two sites were selected for mutagenesis with the aim of altering the surface electrostatics as well as removing a potentially deamidation-prone asparagine residue. The N177D cutinase variant was affirmed to be more resilient to temperature increase with a 2.7-fold increase in half-life at 50°C as compared with wild-type enzyme, while, the activity at 25°C is not compromised. Furthermore, the increase in thermal tolerance of this variant is accompanied by an increase in optimal temperature. Another variant, the L172K, however, exhibited higher enzymatic performance towards phenyl ester substrates of longer carbon chain length, yet its thermal stability is inversely affected. In order to restore the thermal stability of L172K, we constructed a L172K/N177D double variant and showed that these two mutations yield an improved variant with enhanced activity towards phenyl ester substrates and enhanced thermal stability. Taken together, our study may provide valuable information for enhancing catalytic performance and thermal stability in future engineering endeavors.
    Matched MeSH terms: Carboxylic Ester Hydrolases/genetics*
  5. Nyon MP, Rice DW, Berrisford JM, Huang H, Moir AJ, Craven CJ, et al.
    PMID: 18540061 DOI: 10.1107/S1744309108012086
    Cutinase catalyzes the hydrolysis of water-soluble esters and long-chain triglycerides and belongs to the family of serine hydrolases. The enzyme is thought to represent an evolutionary link between the esterase and lipase families and has potential applications in a wide range of industrial hydrolytic processes, for which an understanding of the molecular basis of its substrate specificity is critical. Glomerella cingulata cutinase has been cloned and the protein has been overexpressed in Escherichia coli, purified and subsequently crystallized in a wide range of different crystal forms in the presence and absence of inhibitors. The best crystals are those of the apo cutinase, which diffract to beyond 1.6 A resolution and belong to space group P4(1)2(1)2 or P4(3)2(1)2. Crystals of cutinase with the inhibitors PETFP or E600 belong to space groups P2(1)2(1)2(1) and P2(1), respectively, and diffract to approximately 2.5 A resolution. All of the crystals are suitable for structural studies, which are currently ongoing.
    Matched MeSH terms: Carboxylic Ester Hydrolases/genetics
  6. Tee KK, Pon CK, Kamarulzaman A, Ng KP
    AIDS, 2005 Jan 28;19(2):119-26.
    PMID: 15668536
    OBJECTIVES: To investigate the molecular epidemiology of HIV-1 and to screen for the emergence of intersubtype recombinants in Kuala Lumpur, Malaysia.

    DESIGN: A molecular epidemiology study was conducted among HIV-1 seropositive patients attending the University Malaya Medical Center (UMMC) from July 2003 to June 2004.

    METHODS: Protease (PR) and reverse transcriptase (RT) gene sequences were derived from drug resistance genotyping assay of 100 newly diagnosed or antiretroviral-naive patients. These were phylogenetically analysed to determine the subtypes and recombination breakpoint analyses were performed on intersubtype recombinants to estimate the recombination breakpoint(s).

    RESULTS: CRF01_AE predominated in Kuala Lumpur with 65% in both PR and RT genes. B subtype was detected at 14% and 12% in PR and RT genes, respectively. C subtype was present at 1% in both genes. Overall, the concordance of PR and RT genes in discriminating subtypes/circulating recombinant forms (CRF) was high at 96%. In this study, novel CRF01_AE/B intersubtype recombinants were detected at high prevalence (22%), including those isolates with subtype discordance. Thai variants of CRF01_AE and B subtype were involved in the genesis of these unique recombinant forms (URF). Interestingly, 19 CRF01_AE/B intersubtype recombinant isolates shared similar recombination breakpoints in both PR and RT genes. Several distinct URF were also identified.

    CONCLUSION: PR and RT genes can be utilized for subtype/CRF assessment with high degree of agreement, allowing concurrent surveillance of circulating HIV-1 subtypes with antiretroviral drug resistance genotyping tests. The emergence of highly identical CRF01_AE/B intersubtype recombinants suggests the possibility of the appearance of a new circulating recombinant form in Kuala Lumpur.

    Matched MeSH terms: Peptide Hydrolases/genetics
  7. Maas RR, Iwanicka-Pronicka K, Kalkan Ucar S, Alhaddad B, AlSayed M, Al-Owain MA, et al.
    Ann Neurol, 2017 Dec;82(6):1004-1015.
    PMID: 29205472 DOI: 10.1002/ana.25110
    OBJECTIVE: 3-Methylglutaconic aciduria, dystonia-deafness, hepatopathy, encephalopathy, Leigh-like syndrome (MEGDHEL) syndrome is caused by biallelic variants in SERAC1.

    METHODS: This multicenter study addressed the course of disease for each organ system. Metabolic, neuroradiological, and genetic findings are reported.

    RESULTS: Sixty-seven individuals (39 previously unreported) from 59 families were included (age range = 5 days-33.4 years, median age = 9 years). A total of 41 different SERAC1 variants were identified, including 20 that have not been reported before. With the exception of 2 families with a milder phenotype, all affected individuals showed a strikingly homogeneous phenotype and time course. Severe, reversible neonatal liver dysfunction and hypoglycemia were seen in >40% of all cases. Starting at a median age of 6 months, muscular hypotonia (91%) was seen, followed by progressive spasticity (82%, median onset = 15 months) and dystonia (82%, 18 months). The majority of affected individuals never learned to walk (68%). Seventy-nine percent suffered hearing loss, 58% never learned to speak, and nearly all had significant intellectual disability (88%). Magnetic resonance imaging features were accordingly homogenous, with bilateral basal ganglia involvement (98%); the characteristic "putaminal eye" was seen in 53%. The urinary marker 3-methylglutaconic aciduria was present in virtually all patients (98%). Supportive treatment focused on spasticity and drooling, and was effective in the individuals treated; hearing aids or cochlear implants did not improve communication skills.

    INTERPRETATION: MEGDHEL syndrome is a progressive deafness-dystonia syndrome with frequent and reversible neonatal liver involvement and a strikingly homogenous course of disease. Ann Neurol 2017;82:1004-1015.

    Matched MeSH terms: Carboxylic Ester Hydrolases/genetics*
  8. Darah I, Sumathi G, Jain K, Lim SH
    Appl Biochem Biotechnol, 2011 Dec;165(7-8):1682-90.
    PMID: 21947762 DOI: 10.1007/s12010-011-9387-8
    Agitation speed was found to influence the tannase production and fungal growth of Aspergillus niger FETL FT3. The optimal agitation speed was at 200 rpm which produced 1.41 U/ml tannase and 3.75 g/l of fungal growth. Lower or higher agitation speeds than 200 rpm produced lower enzyme production and fungal growth. Based on the SEM and TEM micrograph observation, there was a significant correlation between agitation speed and the morphology of the fungal mycelia. The results revealed an increase of the enzyme production with the change of the fungal growth morphology from filamentous to pelleted growth forms. However, the exposure to higher shear stress with an increasing agitation speed of the shaker also resulted in lower biomass yields as well as enzyme production.
    Matched MeSH terms: Carboxylic Ester Hydrolases/genetics
  9. Goh KM, Gan HM, Chan KG, Chan GF, Shahar S, Chong CS, et al.
    PLoS One, 2014;9(6):e90549.
    PMID: 24603481 DOI: 10.1371/journal.pone.0090549
    Species of Anoxybacillus are widespread in geothermal springs, manure, and milk-processing plants. The genus is composed of 22 species and two subspecies, but the relationship between its lifestyle and genome is little understood. In this study, two high-quality draft genomes were generated from Anoxybacillus spp. SK3-4 and DT3-1, isolated from Malaysian hot springs. De novo assembly and annotation were performed, followed by comparative genome analysis with the complete genome of Anoxybacillus flavithermus WK1 and two additional draft genomes, of A. flavithermus TNO-09.006 and A. kamchatkensis G10. The genomes of Anoxybacillus spp. are among the smaller of the family Bacillaceae. Despite having smaller genomes, their essential genes related to lifestyle adaptations at elevated temperature, extreme pH, and protection against ultraviolet are complete. Due to the presence of various competence proteins, Anoxybacillus spp. SK3-4 and DT3-1 are able to take up foreign DNA fragments, and some of these transferred genes are important for the survival of the cells. The analysis of intact putative prophage genomes shows that they are highly diversified. Based on the genome analysis using SEED, many of the annotated sequences are involved in carbohydrate metabolism. The presence of glycosyl hydrolases among the Anoxybacillus spp. was compared, and the potential applications of these unexplored enzymes are suggested here. This is the first study that compares Anoxybacillus genomes from the aspect of lifestyle adaptations, the capacity for horizontal gene transfer, and carbohydrate metabolism.
    Matched MeSH terms: Glycoside Hydrolases/genetics
  10. Too CL, Murad S, Dhaliwal JS, Larsson P, Jiang X, Ding B, et al.
    Arthritis Res Ther, 2012;14(6):R250.
    PMID: 23164236 DOI: 10.1186/ar4093
    INTRODUCTION: The majority of our knowledge regarding disease-related mechanisms of uncontrolled citrullination and anti-citrullinated protein antibody development in rheumatoid arthritis (RA) was investigated in Caucasian populations. However, peptidylarginine deiminase (PADI) type 4 gene polymorphisms are associated with RA in East Asian populations and weak or no association was found in Caucasian populations. This study explores the association between the PADI4 polymorphisms and RA risk in a multiethnic population residing in South East Asia with the goal of elucidating generalizability of association in non-Caucasian populations.
    METHODS: A total of 320 SNPs from the PADI locus (including PADI1, PADI2, PADI3, PADI4 and PADI6 genes) were genotyped in 1,238 RA cases and 1,571 control subjects from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) case-control study. Additionally, we conducted meta-analysis of our data together with the previously published studies of RA from East Asian populations.
    RESULTS: The overall odds ratio (ORoverall) for the PADI4 (rs2240340) allelic model was 1.11 (95% confidence interval (CI) = 1.00 to 1.23, P = 0.04) and for the genotypic model was 1.20 (95% CI = 1.01 to 1.44, P = 0.04). Haplotype analysis for four selected PADI4 SNPs revealed a significant association of one with susceptibility (P = 0.001) and of another with a protective effect (P = 0.02). The RA susceptibility was further confirmed when combined meta-analysis was performed using these data together with data from five previously published studies from Asia comprising 5,192 RA cases and 4,317 control subjects (ORoverall = 1.23 (95% CI = 1.16 to 1.31, Pheterogeneity = 0.08) and 1.31 (95% CI = 1.20 to 1.44, Pheterogeneity = 0.32) in allele and genotype-based models, respectively). In addition, we also detected a novel association of PADI2 genetic variant rs1005753 with RA (ORoverall = 0.87 (95% CI = 0.77 to 0.99)).
    CONCLUSION: Our study demonstrates an association between PADI4 and RA in the multiethnic population from South East Asia and suggests additional association with a PADI2 gene. The study thus provides further support for the notion that polymorphisms in genes for enzymes responsible for citrullination contribute to RA development in multiple populations of Asian descent.
    Matched MeSH terms: Hydrolases/genetics*
  11. Nishiki I, Minami T, Chen SC, Itami T, Yoshida T
    J Gen Appl Microbiol, 2012;58(6):457-63.
    PMID: 23337581
    Group C Streptococcus dysgalactiae (GCSD) is a pathogen of farmed fish. Almost all GCSD isolates from Asian countries, including Japan, Taiwan, Malaysia, and China, have a serum opacity factor (SOF-FD). Although the SOF-FD sequences in different GCSD isolates are identical, different opacification activities are observed. Three types of variations were observed in the upstream sequence of the sof-FD gene in GCSD isolates with different SOF-FD activities. Type 1 was characterized by insertion of an IS981-like element into the upstream region of the sof-FD gene. In Type 2, an IS981-like element was inserted into the upstream region in a direction opposite to that in Type 1. In Type 3, no IS element was inserted. Type 1 was predominant among Japanese isolates (129 of 133). Isolates from other Asian countries were generally Type 3 (13 of 16). Except for 1 strain, Type 1 strains exhibited opacification activities with optical densities (ODs)>0.6, while Type 2 and Type 3 strains have low opacification activities (ODs >0.2). Only Type 1 strains have putative -10 and -35 promoter regions upstream of the sof-FD gene, and the expression level of the sof-FD gene was higher in Type 1 strains than in Type 2 and Type 3 strains.
    Matched MeSH terms: Peptide Hydrolases/genetics
  12. Vellasamy KM, Vasu C, Puthucheary SD, Vadivelu J
    Microb Pathog, 2009 Sep;47(3):111-7.
    PMID: 19524661 DOI: 10.1016/j.micpath.2009.06.003
    To evaluate the potential role of extracellular proteins in the pathogenicity and virulence of Burkholderia pseudomallei, the activities of several enzymes in the culture filtrates of nine clinical and six environmental isolates were investigated in vitro and in vivo in ICR strain of mice. The production of protease, phosphatase, phospholipase C, superoxide dismutase, catalase and peroxidase were detected in the culture filtrates of all the 15 isolates at different time points of growth 4-24h. Over time, activity of each enzyme at each time point varied. Profile of secretion was similar among the 15 isolates irrespective of source, that is clinical or environmental. Catalase, phosphatase and phospholipase C were found to be increased in 60-100% of the isolates post-passage in mice. In vivo inoculation studies in ICR mice demonstrated a wide difference in their ability to cause bacteraemia, splenic or external abscesses and mortality rate ranged from few days to several weeks.
    Matched MeSH terms: Phosphoric Monoester Hydrolases/genetics
  13. Tay ST, Tan HW, Na SL, Lim SL
    J Med Microbiol, 2011 Nov;60(Pt 11):1591-1597.
    PMID: 21700741 DOI: 10.1099/jmm.0.032854-0
    In this study, six clinical isolates (two from blood, two from urine and one each from a bronchoalveolar lavage and a vaginal swab) were identified as Candida rugosa based on carbohydrate assimilation profiles using API 20C AUX and ID32 C kits (bioMérieux). Sequence analysis of the D1/D2 domain of the yeasts differentiated the isolates into two subgroups, A and B (three isolates per subgroup), which were closely related (99.1-99.6 % nucleotide similarity) to C. rugosa strain ATCC 10571. Compared with the C. rugosa type strain, the intergenic transcribed spacer (ITS) nucleotide similarity for subgroup A was only 89.2 % (29 mismatches and one deletion) and for subgroup B was 93.7 % (20 mismatches). All isolates grew green colonies on Oxoid Chromogenic Candida Agar, with darker pigmentation observed for subgroup A. All isolates were able to grow at 25-42 °C but not at 45 °C. The isolates had identical enzymic profiles, as determined by API ZYM (bioMérieux) analysis, and produced proteinase. High amphotericin MICs (≥1 µg ml(-1)) were noted for two isolates from each subgroup. Dose-dependent susceptibility to fluconazole (MIC 32 µg ml(-1)) was noted in a blood isolate. The biofilms of the isolates demonstrated increased resistance to amphotericin and fluconazole. The greater ITS sequence variability of subgroup A isolates is in support of this yeast being recognized as a distinct species; however, further verification using more sophisticated molecular approaches is required. A sequence comparison study suggested the association of subgroup A with environmental sources and subgroup B with clinical sources. Accurate identification and antifungal susceptibility testing of C. rugosa are important in view of its decreased susceptibility to amphotericin and fluconazole. The ITS region has been shown to be a valuable region for differentiation of closely related subgroups of C. rugosa.
    Matched MeSH terms: Peptide Hydrolases/genetics*
  14. Yew SM, Chan CL, Ngeow YF, Toh YF, Na SL, Lee KW, et al.
    Sci Rep, 2016 05 31;6:27008.
    PMID: 27243961 DOI: 10.1038/srep27008
    Cladosporium sphaerospermum, a dematiaceous saprophytic fungus commonly found in diverse environments, has been reported to cause allergy and other occasional diseases in humans. However, its basic biology and genetic information are largely unexplored. A clinical isolate C. sphaerospermum genome, UM 843, was re-sequenced and combined with previously generated sequences to form a model 26.89 Mb genome containing 9,652 predicted genes. Functional annotation on predicted genes suggests the ability of this fungus to degrade carbohydrate and protein complexes. Several putative peptidases responsible for lung tissue hydrolysis were identified. These genes shared high similarity with the Aspergillus peptidases. The UM 843 genome encodes a wide array of proteins involved in the biosynthesis of melanin, siderophores, cladosins and survival in high salinity environment. In addition, a total of 28 genes were predicted to be associated with allergy. Orthologous gene analysis together with 22 other Dothideomycetes showed genes uniquely present in UM 843 that encode four class 1 hydrophobins which may be allergens specific to Cladosporium. The mRNA of these hydrophobins were detected by RT-PCR. The genomic analysis of UM 843 contributes to the understanding of the biology and allergenicity of this widely-prevalent species.
    Matched MeSH terms: Peptide Hydrolases/genetics*
  15. 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.
    Matched MeSH terms: Glycoside Hydrolases/genetics
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