Displaying publications 1 - 20 of 25 in total

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  1. Fulltext Phenotype-genotype analyses of clinically diagnosed Malaysian familial hypercholestrolemic patients
    Al-Khateeb A, Al-Talib H, Mohamed MS, Yusof Z, Zilfalil BA
    Adv Clin Exp Med, 2013 Jan-Feb;22(1):57-67.
    PMID: 23468263
    BACKGROUND: Familial hypercholesterolemia and familial defective apo lipoprotein B are genetic disorders caused by defects in the low-density lipoprotein receptor gene and apo lipoprotein B 100 genes, respectively. The clinical phenotype of both diseases is characterized by increased plasma levels of total cholesterol and low density lipoprotein cholesterol, tendinous xanthomata, and premature coronary heart disease.
    OBJECTIVES: The aim of this study is to perform an association study between different gene sequence variants in low-density lipoprotein and apo lipoprotein B 100 genes to the clinical finding and lipid profile parameters of the study subjects.
    MATERIAL AND METHODS: A group of 164 familial hypercholesterolemic patients were recruited. The promoter region, exon 2-15 of the low density lipoprotein gene and parts of exon 26 and 29 of apo lipoprotein B 100 gene were screened by Denaturating Gradient High Performance Liquid Chromatography.
    RESULTS: For the apo lipoprotein B 100 gene, those with apo lipoprotein B 100 gene mutation have a significantly higher frequency of cardiovascular disease (P = 0.045), higher low density lipoprotein cholesterol and total cholesterol: high density lipoprotein cholesterol ratio than those without mutation (P = 0.03 and 0.02, respectively). For the low density lipoprotein gene defect those with frame shift mutation group showed the worst clinical presentation in terms of low density lipoprotein cholesterol level and cardiovascular frequency.
    CONCLUSIONS: There was a statistically significant association between mutations of low density lipoprotein gene and apo lipoprotein B 100 genes and history of cardiovascular disease, younger age of presentation, family history of hyperlipidemia, tendon xanthoma and low density lipoprotein cholesterol level.
    Study site: Cardiology Clinic, Hospital Universiti Sains Malaysia (HUSM), Kelantan, Malaysia
  2. Fulltext Analysis of sequence variations in low-density lipoprotein receptor gene among Malaysian patients with familial hypercholesterolemia
    Al-Khateeb A, Zahri MK, Mohamed MS, Sasongko TH, Ibrahim S, Yusof Z, et al.
    BMC Med Genet, 2011;12:40.
    PMID: 21418584 DOI: 10.1186/1471-2350-12-40
    Familial hypercholesterolemia is a genetic disorder mainly caused by defects in the low-density lipoprotein receptor gene. Few and limited analyses of familial hypercholesterolemia have been performed in Malaysia, and the underlying mutations therefore remain largely unknown.We studied a group of 154 unrelated FH patients from a northern area of Malaysia (Kelantan). The promoter region and exons 2-15 of the LDLR gene were screened by denaturing high-performance liquid chromatography to detect short deletions and nucleotide substitutions, and by multiplex ligation-dependent probe amplification to detect large rearrangements.
  3. Fulltext Low-density lipoprotein cholesterol goal attainment among Malaysian dyslipidemic patients
    Al-Khateeb A, Mohamed MS, Imran K, Ibrahim S, Zilfalill BA, Yusof Z
    Southeast Asian J. Trop. Med. Public Health, 2011 Mar;42(2):388-94.
    PMID: 21710862
    The aim of the present study was to evaluate Malaysian dyslipidemic patient treatment practices and outcomes. Factors contributing to success in reaching treatment goal were determined. A retrospective review of the records of dyslipidemic patients who attended the Universiti Sains Malaysia Hospital in 2007 was conducted. All the patients were receiving standard recommended doses of statins. Records were analysed for 890 patients. Patients were divided into three categories: 384 patients (43.1%) had coronary heart disease or coronary heart disease risk equivalents, 216 patients (24.3%) had moderate risk for coronary heart disease and 290 patients (32.6%) had low risk. Statins were the most commonly prescribed drug group (92%), of which atorvastatin was the most commonly prescribed drug (50.6%). The overall success rate for reaching goal was 64.2%. The percentages of patients achieving low-density lipoprotein cholesterol targets in the coronary heart disease and coronary heart disease risk equivalents, moderate, and low-risk groups were 50.5, 66.7, and 80.3%, respectively (p < 0.001). Multiple logistic regression showed achievement of therapeutic goal declined with increasing risk group. The baseline low-density lipoprotein cholesterol value was inversely related to therapeutic goal attainment. An inadequate proportion of dyslipidemic patients achieved the National Cholesterol Education Program therapeutic goals for low-density lipoprotein cholesterol, especially those in the coronary heart disease and coronary heart disease risk equivalent group. The achievement of this goal was dependent on baseline low-density lipoprotein cholesterol levels.
  4. Lipid profile parameters in Malaysian dyslipidemic patients
    Al-Khateeb A, Mohamed MS, Imran K, Ibrahim S, Zilfalil BA, Yusof Z
    Kobe J Med Sci, 2011;57(2):E38-48.
    PMID: 22926072
    The importance of serum lipids as cardiovascular risk factors is well recognized. However, most published studies have focused on western countries. The present study aimed to describe and analyze the lipid profile parameters in Malaysian dyslipidemic patients, and to identify concomitant clinical problems and risk factors associated with cardiovascular disease (CVD) among such patients.
  5. Fulltext Pulse wave velocity as a marker of severity of coronary artery disease
    Alarhabi AY, Mohamed MS, Ibrahim S, Hun TM, Musa KI, Yusof Z
    J Clin Hypertens (Greenwich), 2009 Jan;11(1):17-21.
    PMID: 19125854 DOI: 10.1111/j.1751-7176.2008.00061.x
    To determine whether pulse wave velocity (PWV) as a measure of arterial stiffness is a marker of coronary artery diseases (CAD), the authors did a cross-sectional study in 92 patients undergoing coronary angiography for suspected CAD. Arterial stiffness was assessed through recording PWV from the left carotid-right femoral arteries using an automated machine. The mean PWV was higher in patients with CAD than in those without CAD (11.13+/-0.91 vs 8.14+/-1.25 m/sec; P
  6. Fulltext Kinetics and Optimization of Lipophilic Kojic Acid Derivative Synthesis in Polar Aprotic Solvent Using Lipozyme RMIM and Its Rheological Study
    Ishak N, Lajis AFB, Mohamad R, Ariff AB, Mohamed MS, Halim M, et al.
    Molecules, 2018 Feb 24;23(2).
    PMID: 29495254 DOI: 10.3390/molecules23020501
    The synthesis of kojic acid derivative (KAD) from kojic and palmitic acid (C16:0) in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM), was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT) experiments, a high reaction rate (30.6 × 10-3 M·min-1) of KAD synthesis was recorded using acetone, enzyme loading of 1.25% (w/v), reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM) whereby the optimized molar ratio (fatty acid: kojic acid), enzyme loading, reaction temperature and reaction time were 6.74, 1.97% (w/v), 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%). This condition was reevaluated in a 0.5 L stirred tank reactor (STR) where the agitation effects of two impellers; Rushton turbine (RT) and pitch-blade turbine (PBT), were investigated. In the STR, a very high yield of KAD synthesis (84.12%) was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation.
  7. Impaired peripheral microvascular reactivity in patients with nonobstructive coronary artery disease
    Sanip Z, Pahimi N, Bokti NA, Yusof Z, Mohamed MS, W Isa WYH, et al.
    Microcirculation, 2023 Apr 20.
    PMID: 37080549 DOI: 10.1111/micc.12807
    OBJECTIVE: This study aimed to determine whether peripheral microvascular reactivity is impaired in patients with nonobstructive coronary artery disease (NOCAD).

    METHODS: Stable patients presenting with angina were recruited and, based on results from coronary angiography, were categorized into OCAD (coronary stenosis of ≥50%) and NOCAD (stenosis <50%) groups. A control group with no history of angina was also recruited. Forearm skin microvascular reactivity was measured using the laser Doppler blood perfusion monitor and the process of postocclusive skin reactive hyperemia (PORH).

    RESULTS: Patients were categorized into OCAD (n = 42), NOCAD (n = 40), and control (n = 39) groups. Compared with the control group, the PORH perfusion percent change (PORH% change) was significantly lower in the OCAD and NOCAD groups. No significant differences were noted between the OCAD and NOCAD groups. Additionally, the NOCAD group without any coronary obstruction takes a longer time to reach peak perfusion and had lower PORH% change compared with the nonangina control group.

    CONCLUSION: Angina patients with NOCAD have microvascular dysfunction as demonstrated by reduced magnitude of reperfusion with an ischemic stimulus. NOCAD patients without coronary obstruction also displayed a slower response to reperfusion.

  8. Fulltext Development of Palm Fatty Acid Distillate-Containing Medium for Biosurfactant Production by Pseudomonas sp. LM19
    Nurfarahin AH, Mohamed MS, Phang LY
    Molecules, 2019 Jul 18;24(14).
    PMID: 31323769 DOI: 10.3390/molecules24142613
    High production costs of biosurfactants are mainly caused by the usage of the expensive substrate and long fermentation period which undermines their potential in bioremediation processes, food, and cosmetic industries even though they, owing to the biodegradability, lower toxicity, and raise specificity traits. One way to circumvent this is to improvise the formulation of biosurfactant-production medium by using cheaper substrate. A culture medium utilizing palm fatty acid distillate (PFAD), a palm oil refinery by-product, was first developed through one-factor-at-a-time (OFAT) technique and further refined by means of the statistical design method of factorial and response surface modeling to enhance the biosurfactant production from Pseudomonas sp. LM19. The results shows that, the optimized culture medium containing: 1.148% (v/v) PFAD; 4.054 g/L KH2PO4; 1.30 g/L yeast extract; 0.023 g/L sodium-EDTA; 1.057 g/L MgSO4·7H2O; 0.75 g/L K2HPO4; 0.20 g/L CaCl2·2H2O; 0.080 g/L FeCl3·6H2O gave the maximum biosurfactant productivity. This study demonstrated that the cell concentration and biosurfactant productivity could reach up to 8.5 × 109 CFU/mL and 0.346 g/L/day, respectively after seven days of growth, which were comparable to the values predicted by an RSM regression model, i.e., 8.4 × 109 CFU/mL and 0.347 g/L/day, respectively. Eleven rhamnolipid congeners were detected, in which dirhamnolipid accounted for 58% and monorhamnolipid was 42%. All in all, manipulation of palm oil by-products proved to be a feasible substrate for increasing the biosurfactant production about 3.55-fold as shown in this study.
  9. Fulltext Culture Medium Development for Microbial-Derived Surfactants Production-An Overview
    Nurfarahin AH, Mohamed MS, Phang LY
    Molecules, 2018 May 01;23(5).
    PMID: 29723959 DOI: 10.3390/molecules23051049
    Surfactants are compounds that can reduce the surface tension between two different phases or the interfacial tension of the liquid between water and oil, possessing both hydrophilic and hydrophobic moieties. Biosurfactants have traits that have proven to be advantageous over synthetic surfactants, but these compounds do not compete economically with synthetic surfactants. Different alternatives increase the yield of biosurfactants; development of an economical production process and the usage of cheaper substrates during process have been employed. One of the solutions relies on the suitable formulation of a production medium by including alternative raw materials sourced from agro-wastes, hydrocarbons, or by-products of a process might help in boosting the biosurfactant production. Since the nutritional factors required will be different among microorganisms, the establishment of a suitable formulation for biosurfactant production will be challenging. The present review describes various nutrients and elements considered in the formulation of a production medium with an approach focusing on the macronutrient (carbon, nitrogen source, and C/N ratio), minerals, vitamins, metabolic regulators, and salinity levels which may aid in the study of biosurfactant production in the future.
  10. Islamic bioethical deliberation on the issue of newborns with disorders of sex development
    Mohamed MS, Noor SN
    Sci Eng Ethics, 2015 Apr;21(2):429-40.
    PMID: 24664170 DOI: 10.1007/s11948-014-9534-z
    This article presents the Islamic bioethical deliberation on the issue of sex assignment surgery (SAS) for infants with disorders of sex development (DSD) or intersexed as a case study. The main objective of this study is to present a different approach in assessing a biomedical issue within the medium of the Maqasid al-Shari'ah. Within the framework of the maqasidic scheme of benefits and harms, any practice where benefits are substantial is considered permissible, while those promoting harms are prohibited. The concept of Maqasid al-Shari'ah which is the mechanistic interpretation of Qur'an and Hadith presents the holistic attention of Islam on many life activities, including healthcare. Indeed, this concept encompasses many aspects of worldly life, both for the human individual and collectively for the whole society. In healthcare, the practice of SAS on DSD newborns has presented an assortment of implications on the future livelihood of the affected individual. The process of decision-making seems to be very multifaceted since every element such as the determination of the 'correct' sex and the urgency of early surgery must consider the benefits and harms, as well as the child's rights and best interest. The application of the concept of Maqasid al-Shari'ah, would convey a pragmatic approach that is often disregarded in Western medicine. This approach considers the right of the individual to live life optimally, individually and socially and practice his faith, precisely, in accordance with the assigned gender.
  11. Fulltext Fatal co-infection--melioidosis and leptospirosis
    Hin HS, Ramalingam R, Chunn KY, Ahmad N, Ab Rahman J, Mohamed MS
    Am J Trop Med Hyg, 2012 Oct;87(4):737-40.
    PMID: 22826499 DOI: 10.4269/ajtmh.2012.12-0165
    Co-infection of melioidosis and leptospirosis is uncommon. We report here four such cases, confirmed by blood culture for melioidosis and blood polymerase-chain reaction for leptospirosis, which occurred among rescuers involved in a search and rescue operation for a young man who was suspected to have drowned in Lubuk Yu, a recreational forest in Pahang, Malaysia. Despite treatment, three of the patients died from the co-infection.
  12. Fulltext Enhancement of Biomass and Calcium Carbonate Biomineralization of Chlorellavulgaris through Plackett-Burman Screening and Box-Behnken Optimization Approach
    Chin ZW, Arumugam K, Ashari SE, Faizal Wong FW, Tan JS, Ariff AB, et al.
    Molecules, 2020 Jul 28;25(15).
    PMID: 32731437 DOI: 10.3390/molecules25153416
    The biosynthesis of calcium carbonate (CaCO3) minerals through a metabolic process known as microbially induced calcium carbonate precipitation (MICP) between diverse microorganisms, and organic/inorganic compounds within their immediate microenvironment, gives rise to a cementitious biomaterial that may emerge as a promissory alternative to conventional cement. Among photosynthetic microalgae, Chlorella vulgaris has been identified as one of the species capable of undergoing such activity in nature. In this study, response surface technique was employed to ascertain the optimum condition for the enhancement of biomass and CaCO3 precipitation of C. vulgaris when cultured in Blue-Green (BG)-11 aquaculture medium. Preliminary screening via Plackett-Burman Design showed that sodium nitrate (NaNO3), sodium acetate, and urea have a significant effect on both target responses (p < 0.05). Further refinement was conducted using Box-Behnken Design based on these three factors. The highest production of 1.517 g/L C. vulgaris biomass and 1.143 g/L of CaCO3 precipitates was achieved with a final recipe comprising of 8.74 mM of NaNO3, 61.40 mM of sodium acetate and 0.143 g/L of urea, respectively. Moreover, polymorphism analyses on the collected minerals through morphological examination via scanning electron microscopy and crystallographic elucidation by X-ray diffraction indicated to predominantly calcite crystalline structure.
  13. Fulltext The State of Starch/Hydroxyapatite Composite Scaffold in Bone Tissue Engineering with Consideration for Dielectric Measurement as an Alternative Characterization Technique
    Mohd Roslan MR, Mohd Kamal NL, Abdul Khalid MF, Mohd Nasir NF, Cheng EM, Beh CY, et al.
    Materials (Basel), 2021 Apr 14;14(8).
    PMID: 33919814 DOI: 10.3390/ma14081960
    Hydroxyapatite (HA) has been widely used as a scaffold in tissue engineering. HA possesses high mechanical stress and exhibits particularly excellent biocompatibility owing to its similarity to natural bone. Nonetheless, this ceramic scaffold has limited applications due to its apparent brittleness. Therefore, this had presented some difficulties when shaping implants out of HA and for sustaining a high mechanical load. Fortunately, these drawbacks can be improved by combining HA with other biomaterials. Starch was heavily considered for biomedical device applications in favor of its low cost, wide availability, and biocompatibility properties that complement HA. This review provides an insight into starch/HA composites used in the fabrication of bone tissue scaffolds and numerous factors that influence the scaffold properties. Moreover, an alternative characterization of scaffolds via dielectric and free space measurement as a potential contactless and nondestructive measurement method is also highlighted.
  14. Fulltext A Review on Haematococcus pluvialis Bioprocess Optimization of Green and Red Stage Culture Conditions for the Production of Natural Astaxanthin
    Oslan SNH, Shoparwe NF, Yusoff AH, Rahim AA, Chang CS, Tan JS, et al.
    Biomolecules, 2021 02 10;11(2).
    PMID: 33578851 DOI: 10.3390/biom11020256
    As the most recognizable natural secondary carotenoid astaxanthin producer, the green microalga Haematococcus pluvialis cultivation is performed via a two-stage process. The first is dedicated to biomass accumulation under growth-favoring conditions (green stage), and the second stage is for astaxanthin evolution under various stress conditions (red stage). This mini-review discusses the further improvement made on astaxanthin production by providing an overview of recent works on H. pluvialis, including the valuable ideas for bioprocess optimization on cell growth, and the current stress-exerting strategies for astaxanthin pigment production. The effects of nutrient constituents, especially nitrogen and carbon sources, and illumination intensity are emphasized during the green stage. On the other hand, the significance of the nitrogen depletion strategy and other exogenous factors comprising salinity, illumination, and temperature are considered for the astaxanthin inducement during the red stage. In short, any factor that interferes with the cellular processes that limit the growth or photosynthesis in the green stage could trigger the encystment process and astaxanthin formation during the red stage. This review provides an insight regarding the parameters involved in bioprocess optimization for high-value astaxanthin biosynthesis from H. pluvialis.
  15. Regulation of Stem Cell Technology in Malaysia: Current Status and Recommendations
    Gopalan N, Nor SNM, Mohamed MS
    Sci Eng Ethics, 2020 02;26(1):1-25.
    PMID: 31123979 DOI: 10.1007/s11948-019-00111-5
    Stem cell technology is an emerging science field; it is the unique regenerative ability of the pluripotent stem cell which scientists hope would be effective in treating various medical conditions. While it has gained significant advances in research, it is a sensitive subject involving human embryo destruction and human experimentation, which compel governments worldwide to ensure that the related procedures and experiments are conducted ethically. Based on face-to-face interviews with selected Malaysian ethicists, scientists and policymakers, the objectives and effectiveness of the current Guideline for Stem Cell Research and Therapy (2009) are examined. The study's findings show that the guideline is rather ineffective in ensuring good ethical governance of the technology. A greater extent of unethical conduct is likely present in the private medical clinics or laboratories offering stem cell therapies compared with the public medical institutions providing similar services, as the latter are closely monitored by the governmental agencies enforcing the relevant policies and laws. To address concerns over malpractices or unethical conduct, this paper recommends a comprehensive revision of the current stem cell guideline so that adequate provisions exist to regulate the explicit practices of the private and public stem cell sectors, including false advertising and accountability. The newly revised Malaysian stem cell guideline will align with the Guidelines for Stem Cell Research and Clinical Translation (2016) of the International Society for Stem Cell Research (ISSCR) containing secular but universal moral rules. However, a regulatory policy formulated to govern the technology remains the main thrust of empowering the guideline for compliance among the stakeholders.
  16. Addressing procedural challenges of ethical review system: Towards a better ethical quality of clinical trials review in Malaysia
    See HY, Mohamed MS, Mohd Noor SN, Low WY
    Account Res, 2019 01;26(1):49-64.
    PMID: 30526066 DOI: 10.1080/08989621.2018.1556646
    The review of clinical trials with human participants in Malaysia is governed by a decentralized control system. The clinical trial protocols are reviewed by 13 registered research ethics committees (RECs) in Malaysia. A governmental body, the National Pharmaceutical Control Bureau, is responsible for the inspection and oversight of these registered RECs to ensure that they comply with the regulatory requirements. However, this study highlights that each REC in Malaysia has a different standard operating procedure and ethical review process. Other procedural challenges identified include inadequate membership, poor mechanism for research monitoring after ethical approval, and insufficient resources. Establishments of a national standard of REC and a central ethics committee are suggested to ensure procedural compliance in the oversight of clinical trials in Malaysia. While there is a growing concern that procedural compliance may not have a direct impact on the protection of human subjects, our key point is that an ethical review system compliant with the national standards could serve as a strong framework to support and enhance the ethical quality of decision-making and judgement. We believe that being aware of how influential procedural compliance can be would help committees improve the ethical quality of their research review.
  17. Challenges in the Ethical Review of Clinical and Biomedical Research in Malaysia: A Mixed Methods Study
    See HY, Mohamed MS, Nor SNM, Low WY
    J Empir Res Hum Res Ethics, 2021 12;16(5):487-500.
    PMID: 34292842 DOI: 10.1177/15562646211033191
    Empirical evidence of the ethical review of clinical and biomedical research in Malaysia is limited. We have conducted a convergent mixed methods research, which comprises an online survey and semistructured interviews to examine the challenges in the ethical review of clinical and biomedical research. Data collected reveal that the ethics review process is inconsistent, duplicate, and inadequate. The results indicate a strong need for a centralized ethical review mechanism and a national system for mutual recognition of ethics reviews to improve the effectiveness and efficiency of the ethics review system in Malaysia. A joint research ethics committee review between Malaysia and sponsoring countries for multinational research should also be encouraged as it could address the concerns of the lack of expertise and training.
  18. Fulltext Outbreak of melioidosis and leptospirosis co-infection following a rescue operation
    Mohamed MS, Khair MT, How SH, Rajalingam R, Sahhir K, Norazah A, et al.
    Med J Malaysia, 2012 Jun;67(3):293-7.
    PMID: 23082420 MyJurnal
    We analyzed the epidemiological data of all people who were involved in the search and rescue operation in Lubuk Yu, a natural recreational forest with waterfall and stream. The hospital admission records of the cases who fulfilled the case definition and the environmental samples result taken at Lubuk Yu recreational area were studied. 153 people were exposed to this outbreak, 85 (55.5%) were professional rescuers from various government agencies and 68 (44.5%) were villagers. 21 fulfilled the case definition. Ten cases were confirmed melioidosis, six melioidosis alone and four coinfected with leptospirosis. There were eight deaths in this outbreak, seven were villagers and one professional rescuer. Overall case fatality was 70%. All confirmed melioidosis cases and seven who died had diabetes mellitus. The morbidity rate were higher among the villagers, 23.5% compared to professional rescuers, 5.9%. The case fatality rate were also higher in this group which was 100% compared to 33.3% in professional rescuers. The soil and water samples in Lubuk Yu recreational area were positive for leptospira and Burkholderia pseudomallei. The presence of co-infection and co-morbidities especially diabetes mellitus among the exposed led to the high mortality in this outbreak hence a high index of suspicion is important among the healthcare professionals in the management of melioidosis cases. To avoid similar incident in future, search and rescue operation should be only conducted by professional rescuers with appropriate personal protective equipment. A register of rescuers should be maintained for surveillance and follow up if necessary.
  19. Fulltext Production of single cell oil by Yarrowia lipolytica JCM 2320 using detoxified desiccated coconut residue hydrolysate
    Zainuddin MF, Kar Fai C, Mohamed MS, Abdul Rahman N', Halim M
    PeerJ, 2022;10:e12833.
    PMID: 35251776 DOI: 10.7717/peerj.12833
    Nowadays, the replacement of petro-diesel with biodiesel has raised the concern among the community for the utilization of improper feedstocks and the cost involved. However, these issues can be solved by producing single cell oil (SCO) from lignocellulosic biomass hydrolysates by oleaginous microorganisms. This study introduced Yarrowia lipolytica JCM 2320 with a desiccated coconut residue (DCR) hydrolysate (obtained from the 2% dilute sulphuric acid pretreatment) as a carbon source in generating SCO. However, common inhibitors formed during acid pretreatment of biomass such as five-hydroxymethylfurfural (HMF), furfural, acetic acid and levulinic acid resulting from the sugar degradations may have detrimental effects towards the fermentation process. To visualize the effect of inhibitors on Y. lipolytica, an inhibitory study was conducted by adding 0.5-5.0 g/L of potential inhibitors to the YPD (yeast, peptone and D-glucose) medium. It was found that the presence of furfural at 0.5 g/L would increase the lag phase, which beyond that was detrimental to Y. lipolytica. Furthermore, increasing the five-hydroxymethylfurfural (HMF) concentration would increase the lag phase of Y. lipolytica, whereas, for acetic acid and levulinic acid, it showed a negligible effect. Detoxification was hence conducted to remove the potential inhibitors from the DCR hydrolysate prior its utilization in the fermentation. To examine the possibility of using adsorption resins for the detoxification of DCR hydrolysate, five different resins were tested (Amberlite® XAD-4, Amberlite® XAD-7, Amberlite® IR 120, Amberlite® IRA 96 and Amberlite® IRA 402) with five different concentrations of 1%, 3%, 5%, 10% and 15% (w/v), respectively. At resin concentration of 10%, Amberlite® XAD-4 recorded the highest SCO yield, 2.90 ± 0.02 g/L, whereas the control and the conventional overliming detoxification method, recorded only 1.29 ± 0.01 g/L and 1.27 ± 0.02 g/L SCO accumulation, respectively. Moreover, the fatty acid profile of the oil produced was rich in oleic acid (33.60%), linoleic acid (9.90%), and palmitic acid (14.90%), which indicates the potential as a good biodiesel raw material.
  20. Strategies for improvement of gamma-aminobutyric acid (GABA) biosynthesis via lactic acid bacteria (LAB) fermentation
    Pannerchelvan S, Rios-Solis L, Faizal Wong FW, Zaidan UH, Wasoh H, Mohamed MS, et al.
    Food Funct, 2023 Mar 23.
    PMID: 36951915 DOI: 10.1039/d2fo03936b
    Gamma-aminobutyric acid (GABA) is a non-protein amino acid widely distributed in nature and extensively explored for its numerous physiological functions and effects on metabolic disorders. Lactic acid bacteria (LAB) are one of the most important GABA producers, vigorously pursued due to their high GABA content and generally regarded as safe (GRAS) status that allows for direct formulation in various GABA-enriched food products. To meet the strict requirements of the food and nutraceutical industries, the biosynthesis of GABA is typically preferred over the chemical synthesis route. The production of GABA varies among various strains of LAB and is affected by different fermentation conditions. Hence, optimizing the fermentation conditions to enhance the activity of the key enzyme glutamic acid decarboxylase is essential to maximize GABA production. This paper reviews the beneficial effects of GABA on human health and its applications in fermented food products. A particular emphasis is given to the biosynthetic approach for producing GABA by various LAB species via the microbial fermentation route. Efficient strategies for enhancing GABA production through optimization of the fermentation conditions, mode of fermentation, two-step fermentation, co-culturing approach, immobilization technique and genetic engineering are discussed in detail.
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