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  1. Fulltext Systematic Review of Brain-Eating Amoeba: A Decade Update
    Ahmad Zamzuri M'I, Abd Majid FN, Mihat M, Ibrahim SS, Ismail M, Abd Aziz S, et al.
    Int J Environ Res Public Health, 2023 Feb 09;20(4).
    PMID: 36833715 DOI: 10.3390/ijerph20043021
    INTRODUCTION: Primary amoebic meningoencephalitis (PAM) is a rare but lethal infection of the brain caused by a eukaryote called Naegleria fowleri (N. fowleri). The aim of this review is to consolidate the recently published case reports of N. fowleri infection by describing its epidemiology and clinical features with the goal of ultimately disseminating this information to healthcare personnel.

    METHODS: A comprehensive literature search was carried out using PubMed, Web of Science, Scopus, and OVID databases until 31 December 2022 by two independent reviewers. All studies from the year 2013 were extracted, and quality assessments were carried out meticulously prior to their inclusion in the final analysis.

    RESULTS: A total of 21 studies were selected for qualitative analyses out of the 461 studies extracted. The cases were distributed globally, and 72.7% of the cases succumbed to mortality. The youngest case was an 11-day-old boy, while the eldest was a 75-year-old. Significant exposure to freshwater either from recreational activities or from a habit of irrigating the nostrils preceded onset. The symptoms at early presentation included fever, headache, and vomiting, while late sequalae showed neurological manifestation. An accurate diagnosis remains a challenge, as the symptoms mimic bacterial meningitis. Confirmatory tests include the direct visualisation of the amoeba or the use of the polymerase chain reaction method.

    CONCLUSIONS: N. fowleri infection is rare but leads to PAM. Its occurrence is worldwide with a significant risk of fatality. The suggested probable case definition based on the findings is the acute onset of fever, headache, and vomiting with meningeal symptoms following exposure to freshwater within the previous 14 days. Continuous health promotion and health education activities for the public can help to improve knowledge and awareness prior to engagement in freshwater activities.

  2. Sago starch and its utilisation
    Abd-Aziz S
    J Biosci Bioeng, 2002;94(6):526-9.
    PMID: 16233345
    The importance and development of industrial biotechnology processing has led to the utilisation of microbial enzymes in various applications. One of the important enzymes is amylase, which hydrolyses starch to glucose. In Malaysia, the use of sago starch has been increasing, and it is presently being used for the production of glucose. Sago starch represents an alternative cheap carbon source for fermentation processes that is attractive out of both economic and geographical considerations. Production of fermentable sugars from the hydrolysis of starches is normally carried out by an enzymatic processes that involves two reaction steps, liquefaction and saccharification, each of which has different temperature and pH optima with respect to the maximum reaction rate. This method of starch hydrolysis requires the use of an expensive temperature control system and a complex mixing device. Our laboratory has investigated the possibility of using amylolytic enzyme-producing microorganisms in the continuous single-step biological hydrolysis of sago flour for the production of a generic fermentation medium. The ability of a novel DNA-recombinated yeast, Saccharomyces cerevisiae strain YKU 107 (expressing alpha-amylase production) to hydrolyse gelatinised sago starch production has been studied with the aim of further utilizing sago starch to obtain value-added products.
  3. Sago pith residue as an alternative cheap substrate for fermentable sugars production
    Linggang S, Phang LY, Wasoh MH, Abd-Aziz S
    Appl Biochem Biotechnol, 2012 May;167(1):122-31.
    PMID: 22528646 DOI: 10.1007/s12010-012-9592-0
    Sago pith residue is one of the most abundant lignocellulosic biomass which can serve as an alternative cheap substrate for fermentable sugars production. This residue is the fibrous waste left behind after the starch extraction process and contains significant amounts of starch (58%), cellulose (23%), hemicellulose (9.2%) and lignin (3.9%). The conversion of sago pith residue into fermentable sugars is commonly performed using cellulolytic enzymes or known as cellulases. In this study, crude cellulases were produced by two local isolates, Trichoderma asperellum UPM1 and Aspergillus fumigatus, UPM2 using sago pith residue as substrate. A. fumigatus UPM2 gave the highest FPase, CMCase and β-glucosidase activities of 0.39, 23.99 and 0.78 U/ml, respectively, on day 5. The highest activity of FPase, CMCase and β-glucosidase by T. asperellum UPM1 was 0.27, 12.03 and 0.42 U/ml, respectively, on day 7. The crude enzyme obtained from A. fumigatus UPM2 using β-glucosidase as the rate-limiting enzyme (3.9, 11.7 and 23.4 IU) was used for the saccharification process to convert 5% (w/v) sago pith residue into reducing sugars. Hydrolysis of sago pith residue using crude enzyme containing β-glucosidase with 23.4 IU, produced by A. fumigatus UPM2 gave higher reducing sugars production of 20.77 g/l with overall hydrolysis percentage of 73%.
  4. Fulltext Reduction of the acidity and peroxide numbers of tengkawang butter (Shorea stenoptera) using thermal and acid activated bentonites
    Darmawan MA, Muhammad BZ, Harahap AFP, Ramadhan MYA, Sahlan M, Haryuni, et al.
    Heliyon, 2020 Dec;6(12):e05742.
    PMID: 33364505 DOI: 10.1016/j.heliyon.2020.e05742
    Tengkawang fat (Shorea stenoptera), from an indigenous plant of the Kalimantan forest, has excellent potential as an alternative source of vegetable fat because it has a high level of fatty acids composition. Activated natural bentonite can be used as a bleaching agent to improve the quality of tengkawang fat. This research aims to reduce the acidity, peroxide number values and identify the physicochemical properties (fatty acid composition, nutrients, and thermal) of tengkawang butter. Initially, tengkawang samples from Nanga Yen and Sintang were pre-treated using the degumming process with 1% phosphoric acid and the neutralization process with a 1 M NaOH 10% w/w solution. The results show that the acidity (mg NaOH/g) of the tengkawang fat samples was reduced from 11.00 to 3.36 when using bentonite activated at 200 °C. The bentonite activated with 0.5 M HCl reduced the acidity to 3.61. The peroxide number (meq O2/kg) of the tengkawang fat samples was reduced from 9.45 to 4.84 and 3.47 by bleaching with thermal-activated and acid-activated bentonites, respectively. Peroxide value correlates with β-carotene content. The smaller of the β-carotene content, the smaller the peroxide value. The acidity, peroxide number, and iodine number values from tengkawang fat after treatment adhere to the SNI 2903: 2016 standard. The main content of fatty acids in tengkawang fat is palmitic acid, stearic acid, and oleic acid. These results show that both products are suitable for the food industry in terms of the acid and peroxide numbers. The application of this research results will assist local people in increasing the economic value of the product from tengkawang plant, which is an indigenous plant from Kalimantan.
  5. Fulltext Recovery of glucose from residual starch of sago hampas for bioethanol production
    Awg-Adeni DS, Bujang KB, Hassan MA, Abd-Aziz S
    Biomed Res Int, 2013;2013:935852.
    PMID: 23509813 DOI: 10.1155/2013/935852
    Lower concentration of glucose was often obtained from enzymatic hydrolysis process of agricultural residue due to complexity of the biomass structure and properties. High substrate load feed into the hydrolysis system might solve this problem but has several other drawbacks such as low rate of reaction. In the present study, we have attempted to enhance glucose recovery from agricultural waste, namely, "sago hampas," through three cycles of enzymatic hydrolysis process. The substrate load at 7% (w/v) was seen to be suitable for the hydrolysis process with respect to the gelatinization reaction as well as sufficient mixture of the suspension for saccharification process. However, this study was focused on hydrolyzing starch of sago hampas, and thus to enhance concentration of glucose from 7% substrate load would be impossible. Thus, an alternative method termed as cycles I, II, and III which involved reusing the hydrolysate for subsequent enzymatic hydrolysis process was introduced. Greater improvement of glucose concentration (138.45 g/L) and better conversion yield (52.72%) were achieved with the completion of three cycles of hydrolysis. In comparison, cycle I and cycle II had glucose concentration of 27.79 g/L and 73.00 g/L, respectively. The glucose obtained was subsequently tested as substrate for bioethanol production using commercial baker's yeast. The fermentation process produced 40.30 g/L of ethanol after 16 h, which was equivalent to 93.29% of theoretical yield based on total glucose existing in fermentation media.
  6. Fulltext Production of Biosurfactant Produced from Used Cooking Oil by Bacillus sp. HIP3 for Heavy Metals Removal
    Md Badrul Hisham NH, Ibrahim MF, Ramli N, Abd-Aziz S
    Molecules, 2019 Jul 18;24(14).
    PMID: 31323813 DOI: 10.3390/molecules24142617
    Heavy metals from industrial effluents and sewage contribute to serious water pollution in most developing countries. The constant penetration and contamination of heavy metals into natural water sources may substantially raise the chances of human exposure to these metals through ingestion, inhalation, or skin contact, which could lead to liver damage, cancer, and other severe conditions in the long term. Biosurfactant as an efficient biological surface-active agent may provide an alternative solution for the removal of heavy metals from industrial wastes. Biosurfactants exhibit the properties of reducing surface and interfacial tension, stabilizing emulsions, promoting foaming, high selectivity, and specific activity at extreme temperatures, pH, and salinity, and the ability to be synthesized from renewable resources. This study aimed to produce biosurfactant from renewable feedstock, which is used cooking oil (UCO), by a local isolate, namely Bacillus sp. HIP3 for heavy metals removal. Bacillus sp. HIP3 is a Gram-positive isolate that gave the highest oil displacement area with the lowest surface tension, of 38 mN/m, after 7 days of culturing in mineral salt medium and 2% (v/v) UCO at a temperature of 30 °C and under agitation at 200 rpm. An extraction method, using chloroform:methanol (2:1) as the solvents, gave the highest biosurfactant yield, which was 9.5 g/L. High performance liquid chromatography (HPLC) analysis confirmed that the biosurfactant produced by Bacillus sp. HIP3 consists of a lipopeptide similar to standard surfactin. The biosurfactant was capable of removing 13.57%, 12.71%, 2.91%, 1.68%, and 0.7% of copper, lead, zinc, chromium, and cadmium, respectively, from artificially contaminated water, highlighting its potential for bioremediation.
  7. Fulltext Preparation of bioactive peptides with high angiotensin converting enzyme inhibitory activity from winged bean [Psophocarpus tetragonolobus (L.) DC.] seed
    Wan Mohtar WA, Hamid AA, Abd-Aziz S, Muhamad SK, Saari N
    J Food Sci Technol, 2014 Dec;51(12):3658-68.
    PMID: 25477632 DOI: 10.1007/s13197-012-0919-1
    Winged bean [Psophocarpus tetragonolobus (L.) DC.] seed is a potential underexploited source of vegetable protein due to its high protein content. In the present work, undefatted and defatted winged bean seed hydrolysates, designated as UWBSH and DWBSH, respectively were produced separately by four proteolytic enzymes namely Flavourzyme, Alcalase, Bromelain, and Papain using pH-stat method in a batch reactor. Enzymatic hydrolysis was carried out over a period of 0.5 to 5 h. UWBSH and DWBSH produced were tested for their ACE inhibitory activity in relation to the hydrolysis time and degree of hydrolysis (DH). Maximum ACE inhibitory activity, both for UWBSH and DWBSH, were observed during 3 to 5 h of hydrolysis. Both, UWBSH (DH 91.84 %), and DWSBH (DH 18.72 %), produced by Papain at 5 h hydrolysis, exhibited exceptionally high ACE inhibitory activity with IC50 value 0.064 and 0.249 mg mL(-1), respectively. Besides, papain-produced UWBSH and DWBSH were further fractionated into three fractions based on molecular weight (UWBSH-I, <10 kDa; UWBSH-II, <5 kDa; UWBSH-III, <2 kDa) and (DWBSH-I, <10 kDa; DWBSH-II, <5 kDa; DWBSH-III, <2 kDa). UWBSH-III revealed the highest ACE inhibitory activity (IC50 0.003 mg mL(-1)) compared with DWBSH-III (IC50 0.130 mg mL(-1)). The results of the present investigation revealed that winged bean seed hydrolysates can be explored as a potential source of ACE inhibitory peptides suggesting their uses for physiological benefits as well as for other functional food applications.
  8. Fulltext Pre-treatment of Oil Palm Biomass for Fermentable Sugars Production
    Rizal NFAA, Ibrahim MF, Zakaria MR, Abd-Aziz S, Yee PL, Hassan MA
    Molecules, 2018 Jun 07;23(6).
    PMID: 29880760 DOI: 10.3390/molecules23061381
    Malaysia is the second largest palm oil producer in the world and this industry generates more than 80 million tonnes of biomass every year. When considering the potential of this biomass to be used as a fermentation feedstock, many studies have been conducted to develop a complete process for sugar production. One of the essential processes is the pre-treatment to modify the lignocellulosic components by altering the structural arrangement and/or removing lignin component to expose the internal structure of cellulose and hemicellulose for cellulases to digest it into sugars. Each of the pre-treatment processes that were developed has their own advantages and disadvantages, which are reviewed in this study.
  9. Potential non-phytopathogenic filamentous fungi for bioconversion of domestic wastewater sludge
    Molla AH, Fakhru'l-Razi A, Hanafi MM, Abd-Aziz S, Alam MZ
    J Environ Sci Health A Tox Hazard Subst Environ Eng, 2002 Sep;37(8):1495-507.
    PMID: 12369641
    Ten filamentous fungi adapted to domestic wastewater sludge (DWS) were further studied to evaluate their potential in terms of adaptation to higher sludge supplemented growing media and phytopathogenicity (induction of diseases to plants) to three germinating crop (Corn: Zea mays, Mung bean: Phaseolus aureus and Mustard: Brassica napus) seeds. The performances of the fungi in seed germination were evaluated based on percent germination index (GI) and infected/spotted seeds on direct fungal biomass (FBM) and fungal metabolite (FM). Significantly the highest biomass production was achieved with RW-P1 512 and Penicillium corylophilum (WW-P1003) at the highest (25%) sludge supplemented growing media that implied its excellent potentiality of adaptation and multiplication to domestic wastewater sludge. Significantly encouraging results of percent GI and spotted/infected seedlings were observed in FM than FBM by all fungi except the strain Aspergillus niger. A. niger gave the poorest percent of GI (24.30, 26.98 and 00.00%) and the highest percent of infected/spotted seeds (70, 100, and 100%) using FBM for corn, mung bean and mustard, respectively. On the other hand, comparatively the highest percent of GI (107.99, 106.25 and 117.67%) and the lowest percent of spotted/infected seedlings (3.3, 3.3 and 3.3%) were achieved with the isolate RW-P1 512 using FM. In FBM, the superior results of percent GI (86.61, 95.92 and 83.87%) and spotted/infected seedlings (3.3, 63.3 and 43.3%) were obtained by A. versicolor. Several crop seeds were responded differently for different fungal treatments. Hundred percent infected/spotted seeds in FM were recorded only for mustard with Trichoderma family that implied its strong sensitiveness to its metabolites.
  10. Pineapple (Ananas comosus): A comprehensive review of nutritional values, volatile compounds, health benefits, and potential food products
    Mohd Ali M, Hashim N, Abd Aziz S, Lasekan O
    Food Res Int, 2020 11;137:109675.
    PMID: 33233252 DOI: 10.1016/j.foodres.2020.109675
    Pineapple (Ananas comosus) is a tropical fruit that is highly relished for its unique aroma and sweet taste. It is renowned as a flavourful fruit since it contains a number of volatile compounds in small amounts and complex mixtures. Pineapple is also a rich source of minerals and vitamins that offer a number of health benefits. Ranked third behind banana and citrus, the demand for pineapple has greatly increased within the international market. The growth of the pineapple industry in the utilisation of pineapple food-based processing products as well as waste processing has progressed rapidly worldwide. This review discusses the nutritional values, physicochemical composition and volatile compounds, as well as health benefits of pineapples. Pineapple contains considerable amounts of bioactive compounds, dietary fiber, minerals, and nutrients. In addition, pineapple has been proven to have various health benefits including anti-inflammatory, antioxidant activity, monitoring nervous system function, and healing bowel movement. The potential of food products and waste processing of pineapples are also highlighted. The future perspectives and challenges with regard to the potential uses of pineapple are critically addressed. From the review, it is proven that pineapples have various health benefits and are a potential breakthrough in the agricultural and food industries.
  11. Optimized lipase-catalyzed synthesis of adipate ester in a solvent-free system
    Chaibakhsh N, Abdul Rahman MB, Abd-Aziz S, Basri M, Salleh AB, Abdul Rahman RN
    J Ind Microbiol Biotechnol, 2009 Sep;36(9):1149-55.
    PMID: 19479288 DOI: 10.1007/s10295-009-0596-x
    Immobilized Candida antarctica lipase-catalyzed esterification of adipic acid and oleyl alcohol was investigated in a solvent-free system (SFS). Optimum conditions for adipate ester synthesis in a stirred-tank reactor were determined by the response surface methodology (RSM) approach with respect to important reaction parameters including time, temperature, agitation speed, and amount of enzyme. A high conversion yield was achieved using low enzyme amounts of 2.5% w/w at 60 degrees C, reaction time of 438 min, and agitation speed of 500 rpm. The good correlation between predicted value (96.0%) and actual value (95.5%) implies that the model derived from RSM allows better understanding of the effect of important reaction parameters on the lipase-catalyzed synthesis of adipate ester in an organic solvent-free system. Higher volumetric productivity compared to a solvent-based system was also offered by SFS. The results demonstrate that the solvent-free system is efficient for enzymatic synthesis of adipate ester.
  12. Fulltext Optimisation of Simultaneous Saccharification and Fermentation (SSF) for Biobutanol Production Using Pretreated Oil Palm Empty Fruit Bunch
    Md Razali NAA, Ibrahim MF, Kamal Bahrin E, Abd-Aziz S
    Molecules, 2018 Aug 03;23(8).
    PMID: 30081514 DOI: 10.3390/molecules23081944
    This study was conducted in order to optimise simultaneous saccharification and fermentation (SSF) for biobutanol production from a pretreated oil palm empty fruit bunch (OPEFB) by Clostridium acetobutylicum ATCC 824. Temperature, initial pH, cellulase loading and substrate concentration were screened using one factor at a time (OFAT) and further statistically optimised by central composite design (CCD) using the response surface methodology (RSM) approach. Approximately 2.47 g/L of biobutanol concentration and 0.10 g/g of biobutanol yield were obtained after being screened through OFAT with 29.55% increment (1.42 fold). The optimised conditions for SSF after CCD were: temperature of 35 °C, initial pH of 5.5, cellulase loading of 15 FPU/g-substrate and substrate concentration of 5% (w/v). This optimisation study resulted in 55.95% increment (2.14 fold) of biobutanol concentration equivalent to 3.97 g/L and biobutanol yield of 0.16 g/g. The model and optimisation design obtained from this study are important for further improvement of biobutanol production, especially in consolidated bioprocessing technology.
  13. Oil palm empty fruit bunch as alternative substrate for acetone-butanol-ethanol production by Clostridium butyricum EB6
    Ibrahim MF, Abd-Aziz S, Razak MN, Phang LY, Hassan MA
    Appl Biochem Biotechnol, 2012 Apr;166(7):1615-25.
    PMID: 22391689 DOI: 10.1007/s12010-012-9538-6
    Acetone-butanol-ethanol (ABE) production from renewable resources has been widely reported. In this study, Clostridium butyricum EB6 was employed for ABE fermentation using fermentable sugar derived from treated oil palm empty fruit bunch (OPEFB). A higher amount of ABE (2.61 g/l) was produced in a fermentation using treated OPEFB as the substrate when compared to a glucose based medium that produced 0.24 g/l at pH 5.5. ABE production was increased to 3.47 g/l with a yield of 0.24 g/g at pH 6.0. The fermentation using limited nitrogen concentration of 3 g/l improved the ABE yield by 64%. The study showed that OPEFB has the potential to be applied for renewable ABE production by C. butyricum EB6.
  14. Fulltext Novel impedance measurement technique for soluble solid content determination of banana
    Ibrahim, N.U.A., Abd Aziz, S., Nawi, N.M.
    Pertanika Journal of Science & Technology, 2017;25(2):519-526.
    MyJurnal
    Soluble solid content (SSC) is one of the important traits that indicate the ripeness of banana fruits.
    Determination of SSC for banana often requires destructive laboratory analysis on the fruit. An impedance measurement technique was investigated as a non-destructive approach for SSC determination of bananas. A pair of electrocardiogram (ECG) electrode connected to an impedance analyser board was used to measure the impedance value of bananas over the frequency of 19.5 to 20.5 KHz. The SSC measurement was conducted using a pocket refractometer and data was analysed to correlate SSC with impedance values. It was found that the mean of impedance, Z decreased from 10.01 to 99.93 KΩ at the frequency of 20 KHz, while the mean value of SSC increased from 0.58 to 4.93 % Brix from day 1 to day 8. The best correlation between impedance and SSC was found at 20 KHz, with the coefficient of determination, R2 of 0.87. This result indicates the potential of impedance measurement in predicting SSC of banana fruits.
  15. Lipase-catalyzed dimethyl adipate synthesis: response surface modeling and kinetics
    Chaibakhsh N, Rahman MB, Basri M, Salleh AB, Abd-Aziz S
    Biotechnol J, 2010 Aug;5(8):848-55.
    PMID: 20632329 DOI: 10.1002/biot.201000063
    Dimethyl adipate (DMA) was synthesized by immobilized Candida antarctica lipase B-catalyzed esterification of adipic acid and methanol. To optimize the reaction conditions of ester production, response surface methodology was applied, and the effects of four factors namely, time, temperature, enzyme concentration, and molar ratio of substrates on product synthesis were determined. A statistical model predicted that the maximum conversion yield would be 97.6%, at the optimal conditions of 58.5 degrees C, 54.0 mg enzyme, 358.0 min, and 12:1 molar ratio of methanol to adipic acid. The R(2) (0.9769) shows a high correlation between predicted and experimental values. The kinetics of the reaction was also investigated in this study. The reaction was found to obey the ping-pong bi-bi mechanism with methanol inhibition. The kinetic parameters were determined and used to simulate the experimental results. A good quality of fit was observed between the simulated and experimental initial rates.
  16. Fulltext Lard classification from other animal fats using Dielectric Spectroscopy technique
    Amat Sairin, M., Abd Aziz, S., Tan, C.P., Mustafa, S., Abd Gani, S.S., Rokhani, F.Z.
    International Food Research Journal, 2019;26(3):773-782.
    MyJurnal
    Lard adulteration in processed foods is a major public concern as it involves religion and
    health. Most lard discriminating works require huge lab-based equipment and complex sample
    preparation. The objective of the present work was to assess the feasibility of dielectric
    spectroscopy as a method for classification of fats from different animal sources, in particular,
    lard. The dielectric spectra of each animal fat were measured in the radio frequency of 100
    Hz – 100 kHz at 45°C to 55°C. The fatty acid composition of each fat was studied by using
    data from gas chromatography mass spectrometry (GCMS) to explain the dielectric behaviour
    of each fat. The principal component analysis (PCA) and artificial neural network (ANN)
    were used to classify different animal fats based on their dielectric spectra. It was found that
    lard showed the highest dielectric constant spectra among other animal fats, and was mainly
    affected by the composition of C16 and C18 fatty acids. PCA classification plot showed clear
    performance in classifying different animal fats. Finally, ANN classification showed different
    animal fats were classified into their respective groups effectively at high accuracy of 85%.
    Dielectric spectroscopy, in combination with quantitative analysis, was concluded to provide
    rapid method to discriminate lard from other animal fats.
  17. Isolation, screening, and identification of potential cellulolytic and xylanolytic producers for biodegradation of untreated oil palm trunk and its application in saccharification of lemongrass leaves
    Ang SK, Yahya A, Abd Aziz S, Md Salleh M
    Prep Biochem Biotechnol, 2015;45(3):279-305.
    PMID: 24960316 DOI: 10.1080/10826068.2014.923443
    This study presents the isolation and screening of fungi with excellent ability to degrade untreated oil palm trunk (OPT) in a solid-state fermentation system (SSF). Qualitative assay of cellulases and xylanase indicates notable secretion of both enzymes by 12 fungal strains from a laboratory collection and 5 strains isolated from a contaminated wooden board. High production of these enzymes was subsequently quantified in OPT in SSF. Aspergillus fumigates SK1 isolated from cow dung gives the highest xylanolytic activity (648.448 U g(-1)), generally high cellulolytic activities (CMCase: 48.006, FPase: 6.860, beta-glucosidase: 16.328 U g(-1)) and moderate lignin peroxidase activity (4.820 U/g), and highest xylanolytic activity. The xylanase encoding gene of Aspergillus fumigates SK1 was screened using polymerase chain reaction by a pair of degenerate primers. Through multiple alignment of the SK1 strain's xylanase nucleotide sequences with other published xylanases, it was confirmed that the gene belonged to the xylanase glycoside hydrolase family 11 (GH11) with a protein size of 24.49 kD. Saccharification of lemongrass leaves using crude cellulases and xylanase gives the maximum reducing sugars production of 6.84 g/L with glucose as the major end product and traces of phenylpropanic compounds (vanillic acid, p-coumaric acid, and ferulic acid).
  18. In-Silico Characterization of Glycosyl Hydrolase Family 1 β-Glucosidase from Trichoderma asperellum UPM1
    Mohamad Sobri MF, Abd-Aziz S, Abu Bakar FD, Ramli N
    Int J Mol Sci, 2020 Jun 04;21(11).
    PMID: 32512945 DOI: 10.3390/ijms21114035
    β-glucosidases (Bgl) are widely utilized for releasing non-reducing terminal glucosyl residues. Nevertheless, feedback inhibition by glucose end product has limited its application. A noticeable exception has been found for β-glucosidases of the glycoside hydrolase (GH) family 1, which exhibit tolerance and even stimulation by glucose. In this study, using local isolate Trichoderma asperellum UPM1, the gene encoding β-glucosidase from GH family 1, hereafter designated as TaBgl2, was isolated and characterized via in-silico analyses. A comparison of enzyme activity was subsequently made by heterologous expression in Escherichia coli BL21(DE3). The presence of N-terminal signature, cis-peptide bonds, conserved active site motifs, non-proline cis peptide bonds, substrate binding, and a lone conserved stabilizing tryptophan (W) residue confirms the identity of Trichoderma sp. GH family 1 β-glucosidase isolated. Glucose tolerance was suggested by the presence of 14 of 22 known consensus residues, along with corresponding residues L167 and P172, crucial in the retention of the active site's narrow cavity. Retention of 40% of relative hydrolytic activity on ρ-nitrophenyl-β-D-glucopyranoside (ρNPG) in a concentration of 0.2 M glucose was comparable to that of GH family 1 β-glucosidase (Cel1A) from Trichoderma reesei. This research thus underlines the potential in the prediction of enzymatic function, and of industrial importance, glucose tolerance of family 1 β-glucosidases following relevant in-silico analyses.
  19. Improvement of cyclodextrin glycosyltransferase gene expression in Escherichia coli by insertion of regulatory sequences involved in the promotion of RNA transcription
    Ramli N, Abd-Aziz S, Alitheen NB, Hassan MA, Maeda T
    Mol Biotechnol, 2013 Jul;54(3):961-8.
    PMID: 23338983 DOI: 10.1007/s12033-013-9647-7
    Regulation of RNA transcription in controlling the expression of genes at promoter and terminator regions is crucial as the interaction of RNA polymerase occurred at both sites. Gene encoding cyclodextrin glycosyltransferase (CGTase) from Bacillus sp. NR5 UPM isolated in the previous study was used for further construction of pTZCGT-SS, pTZCGT-BS and pTZCGT-BT expression systems for enhancement of CGTase production. The putative promoter regions, -35 and -10 sequences were found in the upstream of the mature gene start codon. Whereas, long inverted repeats sequences which can form a stable stem and loop structure was found downstream of the open reading frame (ORF) of Bacillus sp. NR5 UPM CGTase. The construction of E. coli strain harbouring pTZCGT-BS showed increment of 3.2-fold in CGTase activity compared to the wild type producer. However, insertion of terminator downstream of CGTase gene in E. coli strain harbouring pTZCGT-BT only resulted in 4.42 % increment of CGTase production compared to E. coli strain containing pTZCGT-BS, perhaps due to low intrinsic termination efficiency. Thus, it is suggested that the insertion of the putative promoter regions upstream of the coding sequence for the construction of CGTase expression system will further enhance in the recombinant enzyme production.
  20. Fulltext Improved properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) produced by Comamonas sp. EB172 utilizing volatile fatty acids by regulating the nitrogen source
    Zakaria MR, Ariffin H, Abd-Aziz S, Hassan MA, Shirai Y
    Biomed Res Int, 2013;2013:237806.
    PMID: 24106698 DOI: 10.1155/2013/237806
    This study presents the effect of carbon to nitrogen ratio (C/N) (mol/mol) on the cell growth and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulation by Comamonas sp. EB172 in 2 L fermenters using volatile fatty acids (VFA) as the carbon source. This VFA was supplemented with ammonium sulphate and yeast extract in the feeding solution to achieve C/N (mol/mol) 5, 15, 25, and 34.4, respectively. By extrapolating the C/N and the source of nitrogen, the properties of the polymers can be regulated. The number average molecular weight (M n ) of P(3HB-co-3HV) copolymer reached the highest at 838 × 10(3) Da with polydispersity index (PDI) value of 1.8, when the culture broth was supplemented with yeast extract (C/N 34.4). Tensile strength and Young's modulus of the copolymer containing 6-8 mol% 3HV were in the ranges of 13-14.4 MPa and 0.26-0.34 GPa, respectively, comparable to those of polyethylene (PE). Thus, Comamonas sp. EB172 has shown promising bacterial isolates producing polyhydroxyalkanoates from renewable carbon materials.
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