Displaying publications 21 - 40 of 81 in total

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  1. Fulltext Strategies in fed-batch cultivation on the production performance of Lactobacillus salivarius I 24 viable cells
    Ming LC, Halim M, Rahim RA, Wan HY, Ariff AB
    Food Sci Biotechnol, 2016;25(5):1393-1398.
    PMID: 30263421 DOI: 10.1007/s10068-016-0217-1
    The potential use of fed-batch cultivation (FBC) for improvement of the production of Lactobacillus salivarius I 24 biomass for subsequent use as probiotics was studied using a 2-L stirredtank bioreactor. Three different constant feeding rates (0.1, 0.05, and 0.033 L/h) were applied in FBCs and their effect on carbon metabolism was evaluated. The carbon flux for cell built-up with reduction in lactic acid synthesis was observed in the fed-batch as compared to the batch cultivation mode. The viable cell number obtained in the constant FBC (CFBC) operated at a feeding rate of 0.05 L/h was 8 times higher (10.7×1010 CFU/mL) than that recorded in the batch cultivation. This gave the viable cell yield based on glucose consumed for CFBC of 26 times higher (11.3×1012 CFU/gGlucose) than the batch cultivation. This study demonstrated CFBC, which is simple with minimal use of process control equipment, has an industrial potential for improvement of probiotic production.
  2. Fulltext The Discovery of New Antilisterial Proteins From Paenibacillus polymyxa Kp10 via Genome Mining and Mass Spectrometry
    Mokhtar NFK, Hashim AM, Hanish I, Zulkarnain A, Raja Nhari RMH, Abdul Sani AA, et al.
    Front Microbiol, 2020;11:960.
    PMID: 32714281 DOI: 10.3389/fmicb.2020.00960
    The inhibitory properties of novel antimicrobial proteins against food-borne pathogens such as Listeria monocytogenes offer extensive benefits to the food and medical industries. In this study, we have identified antimicrobial proteins from a milk curd-derived bacterial isolate that exhibits antilisterial activity using genome mining and mass spectrometry analysis. The analysis of the draft genome sequence identified the isolate as Paenibacillus polymyxa Kp10, and predicted the presence of antimicrobial paenibacillin, paenilan, paeninodin, sactipeptides, thiazole-oxazole modified microcin, and histone-like DNA binding protein HU encoded in its genome. Interestingly, nanoLC-MS/MS analysis identified two histone-like DNA binding proteins HU as predicted in silico earlier, exhibiting antilisterial activity. Additionally, translation initiation factor IF-1 and 50S ribosomal protein L29 were also discovered by the mass spectrometry in the active fractions. The antilisterial activity of the four proteins was verified through heterologous protein expression and antimicrobial activity assay in vitro. This study has identified structural regulatory proteins from Paenibacillus possessing antilisterial activity with potential future application in the food and medical industries.
  3. Anti-breast cancer effects of live, heat-killed and cytoplasmic fractions of Enterococcus faecalis and Staphylococcus hominis isolated from human breast milk
    Hassan Z, Mustafa S, Rahim RA, Isa NM
    In Vitro Cell Dev Biol Anim, 2016 Mar;52(3):337-348.
    PMID: 26659392 DOI: 10.1007/s11626-015-9978-8
    Development of tumour that is resistant to chemotherapeutics and synthetic drugs, coupled with their life-threatening side effects and the adverse effects of surgery and hormone therapies, led to increased research on probiotics' anticancer potentials. The current study investigated the potential of live, heat-killed cells (HKC) and the cytoplasmic fractions (CF) of Enterococcus faecalis and Staphylococcus hominis as anti-breast cancer agents. MCF-7 cell line was treated with 25, 50, 100 and 200 μg/mL each of live, HKC and CF of the bacteria; and cytotoxicity was evaluated for 24, 48 and 72 h using MTT assay. The morphological features of the treated cells were examined by fluorescence microscopy. The stage of cell cycle arrest and apoptosis were quantified by flow cytometry. The bacterial effect on non-malignant breast epithelial cell line, MCF-10A, was assessed using MTT assay for 24, 48 and 72 h. All the three forms of the bacteria caused a significant decrease in MCF-7 (up to 33.29%) cell proliferation in concentration- and time-dependent manner. Morphological features of apoptosis like cell death, cell shrinkage and membrane blebbing were observed. Flow cytometry analyses suggested that about 34.60% of treated MCF-7 was undergoing apoptosis. A strong anti-proliferative activity was efficiently induced through sub-G1 accumulation (up to 83.17%) in treated MCF-7 and decreased number in the G0/G1 phase (74.39%). MCF-10A cells treated with both bacteria showed no significant difference with the untreated (>90% viability). These bacteria can be used as good alternative nutraceutical with promising therapeutic indexes for breast cancer because of their non-cytotoxic effects to normal cells.
  4. Fulltext Serum Anti-Müllerian Hormone in Polycystic Ovary Syndrome and its Relationship with Insulin Resistance, Lipid Profile and Adiponectin
    Jun TJ, Jelani AM, Omar J, Rahim RA, Yaacob NM
    Indian J Endocrinol Metab, 2020 04 30;24(2):191-195.
    PMID: 32699789 DOI: 10.4103/ijem.IJEM_305_19
    Objectives: This study was done to estimate serum anti-Müllerian hormone (AMH) level in polycystic ovary syndrome (PCOS) patients and to correlate serum AMH level with insulin resistance, lipid profile, and adiponectin levels.

    Materials and Methods: A cross-sectional study was conducted at Hospital Universiti Sains Malaysia (Hospital USM), Health Campus, Kubang Kerian, Kelantan, Malaysia. Thirty newly diagnosed patients with PCOS attending gynecology clinic between July 2016 and April 2017 were recruited. Fasting venous blood samples were collected from the subjects. Serum AMH, insulin, adiponectin, triglycerides, high-density lipoprotein cholesterol (HDL-C), and plasma glucose levels were measured, and insulin resistance was calculated based on homeostasis model of assessment-insulin resistance (HOMA-IR). The serum AMH level was estimated, and the correlation of serum AMH level with the metabolic parameters was analyzed.

    Results: The median of serum AMH levels in women with PCOS was 6.8 ng/mL (interquartile range: 7.38 ng/mL). There was a significant negative correlation between serum AMH and HOMA-IR or triglyceride levels (r = -0.49, P = 0.006 and r = -0.55, P = 0.002, respectively). A significant positive correlation was observed between serum AMH and serum HDL-C or serum adiponectin levels (r = 0.56, P = 0.001 and r = 0.44, P = 0.014, respectively) in all study subjects.

    Conclusion: The serum AMH level is associated with HOMA-IR, triglycerides, HDL-C, and adiponectin levels, and hence it may be used as a potential cardiometabolic risk marker in women with PCOS.

  5. A finite element study: Finding the best configuration between unilateral, hybrid, and ilizarov in terms of biomechanical point of view
    Abd Aziz AU, Abdul Wahab AH, Abdul Rahim RA, Abdul Kadir MR, Ramlee MH
    Injury, 2020 Nov;51(11):2474-2478.
    PMID: 32798038 DOI: 10.1016/j.injury.2020.08.001
    In an open fracture, the external fixator is one of the definitive treatment options as it could provide the initial stabilisation of the fractured bone. Limited literature discussing on the biomechanical stability between unilateral, hybrid and Ilizarov configurations, principally in treating a femoral fracture. Thus, this study aims to analyse the biomechanical stability of different external fixators via the finite element method (FEM). The present study portrays that different configurations of fixators possess different biomechanical stability, hence leading to different healing rates and complication risks. For the methodology, three-dimensional models of three different external fixators were reconstructed where axial loads were applied on the proximal end of the femur, simulating the stance phase. From the results, the unilateral configuration provides better stability compared to the hybrid and Ilizarov, where it displaced the least with an average percentage difference of 50% for the fixator's frame and 23% for the bone. The unilateral configuration also produced the least interfragmentary movement (0.48 mm) as compared to hybrid (0.62 mm) and Ilizarov (0.61 mm) configurations. Besides, the strain and stress of the unilateral configuration were superior in terms of stability compared to the other two configurations. As a conclusion, the unilateral configuration had the best biomechanical stability as it was able to assist the bone healing process as well as minimising the risk of pin tract infection while treating a femoral fracture.
  6. Fulltext Functional expression of an orchid fragrance gene in Lactococcus lactis
    Song AA, Abdullah JO, Abdullah MP, Shafee N, Rahim RA
    Int J Mol Sci, 2012;13(2):1582-97.
    PMID: 22408409 DOI: 10.3390/ijms13021582
    Vanda Mimi Palmer (VMP), an orchid hybrid of Vanda tesselata and Vanda Tan Chay Yan is a highly scented tropical orchid which blooms all year round. Previous studies revealed that VMP produces a variety of isoprenoid volatiles during daylight. Isoprenoids are well known to contribute significantly to the scent of most fragrant plants. They are a large group of secondary metabolites which may possess valuable characteristics such as flavor, fragrance and toxicity and are produced via two pathways, the mevalonate (MVA) pathway or/and the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. In this study, a sesquiterpene synthase gene denoted VMPSTS, previously isolated from a floral cDNA library of VMP was cloned and expressed in Lactococcus lactis to characterize the functionality of the protein. L. lactis, a food grade bacterium which utilizes the mevalonate pathway for isoprenoid production was found to be a suitable host for the characterization of plant terpene synthases. Through recombinant expression of VMPSTS, it was revealed that VMPSTS produced multiple sesquiterpenes and germacrene D dominates its profile.
  7. Green synthesis palladium nanoparticles mediated by white tea (Camellia sinensis) extract with antioxidant, antibacterial, and antiproliferative activities toward the human leukemia (MOLT-4) cell line
    Azizi S, Mahdavi Shahri M, Rahman HS, Rahim RA, Rasedee A, Mohamad R
    Int J Nanomedicine, 2017;12:8841-8853.
    PMID: 29276385 DOI: 10.2147/IJN.S149371
    Among nanoparticles used for medical applications, palladium nanoparticles (PdNPs) are among the least investigated. This study was undertaken to develop PdNPs by green synthesis using white tea (W.tea; Camellia sinensis) extract to produce the Pd@W.tea NPs. The Pd@W.tea NPs were characterized by UV-vis spectroscopy and X-ray diffractometry, and evaluated with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The Pd@W.tea NPs were spherical (size 6-18 nm) and contained phenols and flavonoids acquired from the W.tea extract. Pd@W.tea NPs has good 1-diphenyl-2-picrylhydrazyl (DPPH), OH, and NO-scavenging properties as well as antibacterial effects toward Staphylococcus epidermidis and Escherichia coli. MTT assay showed that Pd@W.tea NPs (IC50 =0.006 μM) were more antiproliferative toward the human leukemia (MOLT-4) cells than the W.tea extract (IC50 =0.894 μM), doxorubicin (IC50 =2.133 μM), or cisplatin (IC50 =0.013 μM), whereas they were relatively innocuous for normal human fibroblast (HDF-a) cells. The anticancer cell effects of Pd@W.tea NPs are mediated through the induction of apoptosis and G2/M cell-cycle arrest.
  8. Fulltext Newcastle Disease Virus Hemagglutinin Neuraminidase as a Potential Cancer Targeting Agent
    Baradaran A, Yusoff K, Shafee N, Rahim RA
    J Cancer, 2016;7(4):462-6.
    PMID: 26918060 DOI: 10.7150/jca.13566
    The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) with its immunotherapeutic activities and sialic acid binding abilities is a promising cancer adjuvant. The HN was surfaced displayed on Lactococcus lactis and its cancer targeting ability was investigated via attachment to the MDA-MB231 breast cancers. To surface display the HN protein on the bacterial cell wall, HN was fused to N-acetylmuraminidase (AcmA) anchoring motif of L. lactis and expressed in Chinese hamster ovary cells. The expressed recombinant fusion proteins were purified and mixed with a culture of L. lactis and Lactobacillus plantarum. Immunofluorescence assay showed the binding of the recombinant HN-AcmA protein on the surface of the bacterial cells. The bacterial cells carrying the HN-AcmA protein interacted with the MDA-MB231 breast cancer cells. Direct and fluorescent microscopy confirmed that L. lactis and Lb. plantarum surface displaying the recombinant HN were attached to the breast cancer MDA-MB231 cells, providing evidence for the potential ability of HN in targeting to cancer cells.
  9. A rapid colorimetric screening method for vanillic acid and vanillin-producing bacterial strains
    Zamzuri NA, Abd-Aziz S, Rahim RA, Phang LY, Alitheen NB, Maeda T
    J Appl Microbiol, 2014 Apr;116(4):903-10.
    PMID: 24314059 DOI: 10.1111/jam.12410
    To isolate a bacterial strain capable of biotransforming ferulic acid, a major component of lignin, into vanillin and vanillic acid by a rapid colorimetric screening method.
  10. Biosynthesis of high molecular weight hyaluronic acid by Streptococcus zooepidemicus using oxygen vector and optimum impeller tip speed
    Lai ZW, Rahim RA, Ariff AB, Mohamad R
    J Biosci Bioeng, 2012 Sep;114(3):286-91.
    PMID: 22608992 DOI: 10.1016/j.jbiosc.2012.04.011
    The potential use of n-dodecane and n-hexadecane as oxygen vectors for enhancing hyaluronic acid (HA) biosynthesis by Streptococcus zooepidemicus ATCC 39920 was investigated using a 2-L stirred-tank bioreactor equipped with helical ribbon or Rushton turbine impellers. The volumetric fraction of the oxygen vector influenced the gas-liquid volumetric oxygen transfer coefficient (K(L)a) positively. Batch HA fermentation with 1% (v/v) n-dodecane or 0.5% (v/v) n-hexadecane addition was carried out at different impeller tip speeds. Even though cell growth was lower in the fermentation with oxygen vector addition, the HA productivity and molecular weight were higher when compared to the fermentation without oxygen vector at low impeller tip speed. The highest HA concentration (4.25 gHA/l) and molecular weight (1.54 × 10(7) Da) were obtained when 0.5% (v/v) n-hexadecane and 0.785 m/s impeller tip speed of helical ribbon were used.
  11. Comparison of the efficiencies of attached- versus suspended-growth SBR systems in the treatment of recycled paper mill wastewater
    Muhamad MH, Sheikh Abdullah SR, Abu Hasan H, Abd Rahim RA
    J Environ Manage, 2015 Nov 1;163:115-24.
    PMID: 26311084 DOI: 10.1016/j.jenvman.2015.08.012
    The complexity of residual toxic organics from biologically treated effluents of pulp and paper mills is a serious concern. To date, it has been difficult to choose the best treatment technique because each of the available options has advantages and drawbacks. In this study, two different treatment techniques using laboratory-scale aerobic sequencing batch reactors (SBRs) were tested with the same real recycled paper mill effluent to evaluate their treatment efficiencies. Two attached-growth SBRs using granular activated carbon (GAC) with and without additional biomass and a suspended-growth SBR were used in the treatment of real recycled paper mill effluent at a chemical oxygen demand (COD) level in the range of 800-1300 mg/L, a fixed hydraulic retention time of 24 h and a COD:N:P ratio of approximately 100:5:1. The efficiency of this biological treatment process was studied over a 300-day period. The six most important wastewater quality parameters, namely, chemical oxygen demand (COD), turbidity, ammonia (expressed as NH3-N), phosphorus (expressed as PO4(3)-P), colour, and suspended solids (SS), were measured to compare the different treatment techniques. It was determined that these processes were able to almost completely and simultaneously eliminate COD (99%) and turbidity (99%); the removals of NH3-N (90-100%), PO4(3)-P (66-78%), colour (63-91%), and SS (97-99%) were also sufficient. The overall performance results confirmed that an attached-growth SBR system using additional biomass on GAC is a promising configuration for wastewater treatment in terms of performance efficiency and process stability under fluctuations of organic load. Hence, this hybrid system is recommended for the treatment of pulp and paper mill effluents.
  12. An effective extracellular protein secretion by an ABC transporter system in Escherichia coli: statistical modeling and optimization of cyclodextrin glucanotransferase secretory production
    Low KO, Mahadi NM, Rahim RA, Rabu A, Abu Bakar FD, Murad AM, et al.
    J Ind Microbiol Biotechnol, 2011 Sep;38(9):1587-97.
    PMID: 21336875 DOI: 10.1007/s10295-011-0949-0
    Direct transport of recombinant protein from cytosol to extracellular medium offers great advantages, such as high specific activity and a simple purification step. This work presents an investigation on the potential of an ABC (ATP-binding cassette) transporter system, the hemolysin transport system, for efficient protein secretion in Escherichia coli (E. coli). A higher secretory production of recombinant cyclodextrin glucanotransferase (CGTase) was achieved by a new plasmid design and subsequently by optimization of culture conditions via central composite design. An improvement of at least fourfold extracellular recombinant CGTase was obtained using the new plasmid design. The optimization process consisted of 20 experiments involving six star points and six replicates at the central point. The predicted optimum culture conditions for maximum recombinant CGTase secretion were found to be 25.76 μM IPTG, 1.0% (w/v) arabinose and 34.7°C post-induction temperature, with a predicted extracellular CGTase activity of 68.76 U/ml. Validation of the model gave an extracellular CGTase activity of 69.15 ± 0.71 U/ml, resulting in a 3.45-fold increase compared to the initial conditions. This corresponded to an extracellular CGTase yield of about 0.58 mg/l. We showed that a synergistic balance of transported protein and secretory pathway is important for efficient protein transport. In addition, we also demonstrated the first successful removal of the C-terminal secretion signal from the transported fusion protein by thrombin proteolytic cleavage.
  13. Improved production of live cells of Lactobacillus rhamnosus by continuous cultivation using glucose-yeast extract medium
    Ling LS, Mohamad R, Rahim RA, Wan HY, Ariff AB
    J Microbiol, 2006 Aug;44(4):439-46.
    PMID: 16953180
    In this study, the growth kinetics of Lactobacillus rhamnosus and lactic acid production in continuous culture were assessed at a range of dilution rates (0.05 h(-1) to 0.40 h(-1)) using a 2 L stirred tank fermenter with a working volume of 600 ml. Unstructured models, predicated on the Monod and Luedeking-Piret equations, were employed to simulate the growth of the bacterium, glucose consumption, and lactic acid production at different dilution rates in continuous cultures. The maximum specific growth rate of L. rhamnosus, mu-max, was estimated at 0.40 h(-1), and the Monod cell growth saturation constant, Ks, at approximately 0.25 g/L. Maximum cell viability (1.3 x 10(10) CFU/ml) was achieved in the dilution rate range of D = 0.28 h(-1) to 0.35 h(-1). Both maximum viable cell yield and productivity were achieved at D = 0.35 h(-1). The continuous cultivation of L. rhamnosus at D = 0.35 h(-1) resulted in substantial improvements in cell productivity, of 267% (viable cell count) that achieved via batch cultivation.
  14. Fulltext Optimization of a heterologous signal peptide by site-directed mutagenesis for improved secretion of recombinant proteins in Escherichia coli
    Jonet MA, Mahadi NM, Murad AM, Rabu A, Bakar FD, Rahim RA, et al.
    J. Mol. Microbiol. Biotechnol., 2012;22(1):48-58.
    PMID: 22456489 DOI: 10.1159/000336524
    A heterologous signal peptide (SP) from Bacillus sp. G1 was optimized for secretion of recombinant cyclodextrin glucanotransferase (CGTase) to the periplasmic and, eventually, extracellular space of Escherichia coli. Eight mutant SPs were constructed using site-directed mutagenesis to improve the secretion of recombinant CGTase. M5 is a mutated SP in which replacement of an isoleucine residue in the h-region to glycine created a helix-breaking or G-turn motif with decreased hydrophobicity. The mutant SP resulted in 110 and 94% increases in periplasmic and extracellular recombinant CGTase, respectively, compared to the wild-type SP at a similar level of cell lysis. The formation of intracellular inclusion bodies was also reduced, as determined by sodium dodecyl sulfate-polyacrylamyde gel electrophoresis, when this mutated SP was used. The addition of as low as 0.08% glycine at the beginning of cell growth improved cell viability of the E. coli host. Secretory production of other proteins, such as mannosidase, also showed similar improvement, as demonstrated by CGTase production, suggesting that the combination of an optimized SP and a suitable chemical additive leads to significant improvements of extracellular recombinant protein production and cell viability. These findings will be valuable for the extracellular production of recombinant proteins in E. coli.
  15. Cell Wall-Treated Lactococcus lactis Increases the Plasmid Transfer Efficiency of Internal Ribosome Entry Site-Incorporated Lactococcal Bicistronic Vector into DF1 Cells
    Mat Isa N, Abdul Mutalib NE, Alitheen NB, Song AA, Rahim RA
    J. Mol. Microbiol. Biotechnol., 2017;27(4):246-251.
    PMID: 29055951 DOI: 10.1159/000481257
    This study demonstrates that cell wall treatment of Lactococcus lactis harbouring the internal ribosome entry site-incorporated lactococcal bicistronic vector pNZ:VIG mediated the delivery of genes into an eukaryotic cell line, DF1 cells, through bactofection. Bactofection analysis showed that the pNZ:VIG plasmid in L. lactis can be transferred into DF1 cells and that both the VP2 and gfp genes cloned in the plasmid can be transcribed and translated. The protein band relative to the Mr of VP2 protein (49 kDa) was successfully detected via Western blot analysis, while green fluorescence was successfully detected using a fluorescence microscope. The intensity of the bands detected increased for samples treated with both 1.5% (w/v) glycine and 10 μg/mL of lysozyme when compared to L. lactis treated with glycine alone and without treatment. Cell wall treatment of L. lactis with a combination of both glycine and lysozyme was not only shown to mediate plasmid transfer to DF1 cells, but also to increase the plasmid transfer efficiency.
  16. Effect of annealing temperature on antimicrobial and structural properties of bio-synthesized zinc oxide nanoparticles using flower extract of Anchusa italica
    Azizi S, Mohamad R, Bahadoran A, Bayat S, Rahim RA, Ariff A, et al.
    J. Photochem. Photobiol. B, Biol., 2016 Aug;161:441-9.
    PMID: 27318600 DOI: 10.1016/j.jphotobiol.2016.06.007
    The use of nontoxic biological compounds in the synthesis of nanomaterials is an economic and eco-friendly approach. The present work was undertaken to develop zinc oxide nanoparticles (ZnO-NPs) by a green method using simple precursor from the solution consisting of zinc acetate and the flower extract of Anchusa italica (A. italica). Effect of annealing temperature on structural and antimicrobial properties was investigated. The crystalline structure of ZnO-NPs was shown using X-ray diffraction (XRD) analysis. Transmission electron microscopy (TEM) results showed that ZnO-NPs are hexagonal in shapes with mean particle size of ~8 and ~14nm at 100°C and 200°C annealing temperatures respectively. The optical band gap was increased from 3.27eV to 3.30eV with the decreasing of the particle size. The antimicrobial activity of ZnO-NPs towards Gram positive (Bacillus megaterium and Stapphylococcus aureus) and Gram negative (Escherichia coli and Salmonella typhimurium) pathogens decreased with the increasing of the heat treating temperature. In vitro cytotoxicity studies on Vero cells, a dose dependent toxicity with non-toxic effect of concentration below 142μg/mL was shown. The results indicated that A. italica is an appropriate reaction media to prepare ZnO-NPs for cosmetic and bio-medical productions.
  17. TRANSCRIPTOMIC ANALYSIS OF GRACILARIA CHANGII (RHODOPHYTA) IN RESPONSE TO HYPER- AND HYPOOSMOTIC STRESSES(1)
    Teo SS, Ho CL, Teoh S, Rahim RA, Phang SM
    J Phycol, 2009 Oct;45(5):1093-9.
    PMID: 27032354 DOI: 10.1111/j.1529-8817.2009.00724.x
    Osmotic stress is one of the most significant natural abiotic stresses that occur in the intertidal zones. Seaweeds may physiologically acclimate to changing osmolarity by altering their transcriptome. Here, we investigated the transcriptomic changes of Gracilaria changii (B. M. Xia et I. A. Abbott) I. A. Abbott, J. Zhang et B. M. Xia in response to hyper- and hypoosmotic stresses using a cDNA microarray approach. Microarray analysis revealed that 199 and 200 genes from ∼3,300 genes examined were up- and down-regulated by >2-fold in seaweed samples treated at 50 parts per thousand (ppt) artificial seawater (ASW) compared with those at 30 ppt ASW, respectively. The number of genes that were up- and down-regulated by >2-fold in seaweed samples treated at 10 ppt ASW compared with those at 30 ppt ASW were 154 and 187, respectively. A majority of these genes were only differentially expressed under hyper- or hypoosmotic conditions, whereas 67 transcripts were affected by both stresses. The findings of this study have shed light on the expression profiles of many transcripts during the acclimation of G. changii to hyperosmotic and hypoosmotic conditions. This information may assist in the prioritization of genes to be examined in future studies.
  18. Fulltext Surface display of respiratory syncytial virus glycoproteins in Lactococcus lactis NZ9000
    Lim SH, Jahanshiri F, Rahim RA, Sekawi Z, Yusoff K
    Lett Appl Microbiol, 2010 Dec;51(6):658-64.
    PMID: 20973806 DOI: 10.1111/j.1472-765X.2010.02950.x
    A system for displaying heterologous respiratory syncytial virus (RSV) glycoproteins on the surface of Lactococcus lactis NZ9000 was developed.
  19. Profiling the transcriptome of Gracilaria changii (Rhodophyta) in response to light deprivation
    Ho CL, Teoh S, Teo SS, Rahim RA, Phang SM
    Mar Biotechnol (NY), 2009 Jul-Aug;11(4):513-9.
    PMID: 19043658 DOI: 10.1007/s10126-008-9166-x
    Light regulates photosynthesis, growth and reproduction, yield and properties of phycocolloids, and starch contents in seaweeds. Despite its importance as an environmental cue that regulates many developmental, physiological, and biochemical processes, the network of genes involved during light deprivation are obscure. In this study, we profiled the transcriptome of Gracilaria changii at two different irradiance levels using a cDNA microarray containing more than 3,000 cDNA probes. Microarray analysis revealed that 93 and 105 genes were up- and down-regulated more than 3-fold under light deprivation, respectively. However, only 50% of the transcripts have significant matches to the nonredundant peptide sequences in the database. The transcripts that accumulated under light deprivation include vanadium chloroperoxidase, thioredoxin, ferredoxin component, and reduced nicotinamide adenine dinucleotide dehydrogenase. Among the genes that were down-regulated under light deprivation were genes encoding light harvesting protein, light harvesting complex I, phycobilisome 7.8 kDa linker polypeptide, low molecular weight early light-inducible protein, and vanadium bromoperoxidase. Our findings also provided important clues to the functions of many unknown sequences that could not be annotated using sequence comparison.
  20. Molecular cloning, modeling, and site-directed mutagenesis of type III polyketide synthase from Sargassum binderi (Phaeophyta)
    Baharum H, Morita H, Tomitsuka A, Lee FC, Ng KY, Rahim RA, et al.
    Mar Biotechnol (NY), 2011 Oct;13(5):845-56.
    PMID: 21181422 DOI: 10.1007/s10126-010-9344-5
    Type III polyketide synthases (PKSs) produce an array of metabolites with diverse functions. In this study, we have cloned the complete reading frame encoding type III PKS (SbPKS) from a brown seaweed, Sargassum binderi, and characterized the activity of its recombinant protein biochemically. The deduced amino acid sequence of SbPKS is 414 residues in length, sharing a higher sequence similarity with bacterial PKSs (38% identity) than with plant PKSs. The Cys-His-Asn catalytic triad of PKS is conserved in SbPKS with differences in some of the residues lining the active and CoA binding sites. The wild-type SbPKS displayed broad starter substrate specificity to aliphatic long-chain acyl-CoAs (C(6)-C(14)) to produce tri- and tetraketide pyrones. Mutations at H(331) and N(364) caused complete loss of its activity, thus suggesting that these two residues are the catalytic residues for SbPKS as in other type III PKSs. Furthermore, H227G, H227G/L366V substitutions resulted in increased tetraketide-forming activity, while wild-type SbPKS produces triketide α-pyrone as a major product. On the other hand, mutant H227G/L366V/F93A/V95A demonstrated a dramatic decrease of tetraketide pyrone formation. These observations suggest that His(227) and Leu(366) play an important role for the polyketide elongation reaction in SbPKS. The conformational changes in protein structure especially the cavity of the active site may have more significant effect to the activity of SbPKS compared with changes in individual residues.
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