Displaying publications 1 - 20 of 70 in total

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  1. Bello B, Mustafa S, Tan JS, Ibrahim TAT, Tam YJ, Ariff AB, et al.
    3 Biotech, 2018 Aug;8(8):346.
    PMID: 30073131 DOI: 10.1007/s13205-018-1362-4
    This paper deliberates the extraction, characterization and examination of potential application of soluble polysaccharides of palm kernel cake (PKC) as a prebiotic. The PKC was defatted and crude polysaccharide was obtained through water, citric acid or NaOH extraction. The physiochemical properties of the extracted polysaccharides viz. total carbohydrates, protein content, solubility rate, monosaccharides composition, structural information and thermal properties were also determined. The extracted soluble polysaccharides were further subjected to a digestibility test using artificial human gastric juice. Finally, their prebiotic potential on two probiotics, namely Lactobacillus plantarum ATCC 8014 and Lb. rhamnosus ATCC 53103 were evaluated in vitro. It was observed that PKC contained ash (5.2%), moisture (7.4%), carbohydrates (65.8%), protein (16.5%) and fat (5.1%). There were significant differences (P  95%). Protein content in SCPW, SCPCA and SCPN are 0.72, 0.40 and 0.58, respectively, and the peaks which indicated the presence of protein were observed at approximately 1640 cm-1 (amide I). FTIR spectroscopy revealed that the polysaccharides extracts were linked to β and α-glycosidic bonds and thermal analysis using differential scanning calorimeter (DSC) showed the main degradation temperature of SP is about 121 to 125 °C. The SP were found to be highly resistance (> 96%) to hydrolysis when subjected to artificial human gastric juice. The prebiotics potentials of the polysaccharides on probiotics in vitro demonstrated an increase in proliferation of Lb. plantarum ATCC 8014 and Lb. rhamnosus ATCC 53103 with decrease in the pH of the medium and producing organic acids.All the above findings strongly indicated that polysaccharides extracted from PKC, an industrial waste, have a potential to be exploited as novel prebiotics.
  2. Tan JS, Abbasiliasi S, Ariff AB, Ng HS, Bakar MHA, Chow YH
    3 Biotech, 2018 Jun;8(6):288.
    PMID: 29938157 DOI: 10.1007/s13205-018-1295-y
    This study aimed at recovery of thermostable lipase from Escherichia coli BL21 using porous glass beads grafted with polyethylene glycol (PEG) in aqueous impregnated resins system (AIRS). The influencing parameters such as concentration and pH of extraction solution, concentration of NaCl, size of the beads, and pH of the desorption solution on the partition behaviour of lipase were evaluated. Smaller adsorbent (4 mm) had a 65.5% of recovery yield with approximately two-fold higher purification factor compared to that obtained with the larger adsorbent. Recombinant lipase was purified successfully using AIRS with a purification factor of 7.6 and yield of 78.4% under optimum conditions of 18% (w/w) PEG 4000, 10% (w/w) of potassium citrate at pH 9 with 3% (w/w) of NaCl. Optimum desorption was obtained with 4.0 mm of porous glass beads at pH 9.
  3. Mohd Zin NB, Mohamad Yusof B, Oslan SN, Wasoh H, Tan JS, Ariff AB, et al.
    AMB Express, 2017 Dec;7(1):131.
    PMID: 28651380 DOI: 10.1186/s13568-017-0433-y
    In recent years, many efforts have been directed to explore the methods to reduce the production costs of industrial lipase by improving the yield and the use of low-cost agricultural wastes. Coconut dregs, which is a lignocellulosic by-product from coconut oil and milk processing plants, is rich in cellulose (36%) and crude fat (9%). A newly isolated Bacillus stratosphericus has been demonstrated to perform cellulose hydrolysis on coconut dregs producing fermentable sugars. The highest extracellular lipase activity of 140 U/mL has been achieved in submerged fermentation with acid pre-treated coconut dregs. The lipase was found to be active over a wide range of temperatures and pHs. The activity of lipase can be generally increased by the presence of detergent ingredients such as Tween-80, cetyltrimethylammonium bromide, hydrogen peroxide and phosphate per sulphate. The great compatibility of lipase in commercial detergents has also underlined its potential as an additive ingredient in biodetergent formulations.
  4. Tan JS, Teah KM, Hoe VC, Khairuddin A, Sellapan H, Hayati F, et al.
    Ann Med Surg (Lond), 2020 Nov;59:251-253.
    PMID: 33088499 DOI: 10.1016/j.amsu.2020.10.009
    Background: Adult intussusception is a relatively rare clinical entity. The majority of cases of intussusception in adults are due to a pathologic condition that serves as a lead point and requires surgery. Small bowel intussusception is usually caused by benign or malignant neoplasms appearing at the head of the invagination. Inflammatory fibroid polyp (IFP) of the small bowel is an unusual benign neoplastic lesion that has been rarely reported to cause intussusception, especially in the jejunum.

    Case presentation: We present a rare case of adult intussusception who presented with a triad of intestinal obstruction. Computed tomography revealed small bowel intussusception with bowel ischemia. Intraoperatively, she required resection of the small bowel and primary anastomosis. Macroscopic examination revealed a single pedunculated polyp, which is the lead point of intestinal obstruction and confirmed histologically.

    Conclusion: Inflammatory fibroid polyp should be considered as a cause of intussusception among adults with small bowel obstruction.

  5. Abu Bakar MH, Azmi MN, Shariff KA, Tan JS
    Appl Biochem Biotechnol, 2019 May;188(1):241-259.
    PMID: 30417321 DOI: 10.1007/s12010-018-2920-2
    Withaferin A (WA), a bioactive constituent derived from Withania somnifera plant, has been shown to exhibit many qualifying properties in attenuating several metabolic diseases. The current investigation sought to elucidate the protective mechanisms of WA (1.25 mg/kg/day) on pre-existing obese mice mediated by high-fat diet (HFD) for 12 weeks. Following dietary administration of WA, significant metabolic improvements in hepatic insulin sensitivity, adipocytokines with enhanced glucose tolerance were observed. The hepatic oxidative functions of obese mice treated with WA were improved via augmented antioxidant enzyme activities. The levels of serum pro-inflammatory cytokines and hepatic mRNA expressions of toll-like receptor (TLR4), nuclear factor κB (NF-κB), tumor necrosis factor-α (TNF-α), chemokine (C-C motif) ligand-receptor, and cyclooxygenase 2 (COX2) in HFD-induced obese mice were reduced. Mechanistically, WA increased hepatic mRNA expression of peroxisome proliferator-activated receptors (PPARs), cluster of differentiation 36 (CD36), fatty acid synthase (FAS), carnitine palmitoyltransferase 1 (CPT1), glucokinase (GCK), phosphofructokinase (PFK), and phosphoenolpyruvate carboxykinase (PCK1) that were associated with enhanced lipid and glucose metabolism. Taken together, these results indicate that WA exhibits protective effects against HFD-induced obesity through attenuation of hepatic inflammation, oxidative stress, and insulin resistance in mice.
  6. Kee PE, Lan JC, Yim HS, Tan JS, Chow YH, Ng HS
    Appl Biochem Biotechnol, 2020 May;191(1):376-386.
    PMID: 31907777 DOI: 10.1007/s12010-019-03202-y
    Cytochrome c is a small water-soluble protein that is abundantly found in the mitochondrial intermembrane space of microorganism, plants and mammalians. Ionic liquids (ILs)-based aqueous two-phase electrophoresis system (ATPES) was introduced in this study to investigate the partition efficiency of cytochrome c to facilitate subsequent development of two-phase electrophoresis for the separation of cytochrome c from microbial fermentation. The 1-Hexyl-3-methylimidazolium bromide, (C6mim)Br and potassium citrate salt were selected as the phase-forming components. Effects of phase composition; position of electrodes; pH and addition of neutral salt on the partition efficiency of cytochrome c in the ATPES were evaluated. Highest partition coefficient (K = 179.12 ± 0.82) and yield of cytochrome c in top phase (YT = 99.63% ± 0.00) were recorded with IL/salt ATPES composed of 30% (w/w) (C6mim)Br and 20% (w/w) potassium citrate salt of pH 7 and 3.0% (w/w) NaCl addition with anode at the bottom phase and cathode at the top phase. The SDS-PAGE profile revealed that cytochrome c with a molecular weight of 12 kDa was preferably partitioned to the IL-rich top phase. Present findings suggested that the single-step ATPES is a potential separation approach for the recovery of cytochrome c from microbial fermentation. Graphical Abstract.
  7. Tajuddin S, Khan AM, Chong LC, Wong CL, Tan JS, Ina-Salwany MY, et al.
    Appl Microbiol Biotechnol, 2023 Feb;107(2-3):749-768.
    PMID: 36520169 DOI: 10.1007/s00253-022-12312-3
    Vibrio alginolyticus is a Gram-negative bacterium commonly associated with mackerel poisoning. A bacteriophage that specifically targets and lyses this bacterium could be employed as a biocontrol agent for treating the bacterial infection or improving the shelf-life of mackerel products. However, only a few well-characterized V. alginolyticus phages have been reported in the literature. In this study, a novel lytic phage, named ΦImVa-1, specifically infecting V. alginolyticus strain ATCC 17749, was isolated from Indian mackerel. The phage has a short latent period of 15 min and a burst size of approximately 66 particles per infected bacterium. ΦImVa-1 remained stable for 2 h at a wide temperature (27-75 °C) and within a pH range of 5 to 10. Transmission electron microscopy revealed that ΦImVa-1 has an icosahedral head of approximately 60 nm in diameter with a short tail, resembling those in the Schitoviridae family. High throughput sequencing and bioinformatics analysis elucidated that ΦImVa-1 has a linear dsDNA genome of 77,479 base pairs (bp), with a G + C content of ~ 38.72% and 110 predicted gene coding regions (106 open reading frames and four tRNAs). The genome contains an extremely large virion-associated RNA polymerase gene and two smaller non-virion-associated RNA polymerase genes, which are hallmarks of schitoviruses. No antibiotic genes were found in the ΦImVa-1 genome. This is the first paper describing the biological properties, morphology, and the complete genome of a V. alginolyticus-infecting schitovirus. When raw mackerel fish flesh slices were treated with ΦImVa-1, the pathogen loads reduced significantly, demonstrating the potential of the phage as a biocontrol agent for V. alginolyticus strain ATCC 17749 in the food. KEY POINTS: • A novel schitovirus infecting Vibrio alginolyticus ATCC 17749 was isolated from Indian mackerel. • The complete genome of the phage was determined, analyzed, and compared with other phages. • The phage is heat stable making it a potential biocontrol agent in extreme environments.
  8. Ng ZJ, Zarin MA, Lee CK, Phapugrangkul P, Tan JS
    Arch Oral Biol, 2020 Feb;110:104617.
    PMID: 31794906 DOI: 10.1016/j.archoralbio.2019.104617
    Streptococcus mutans and Candida albicans are the main oral pathogens which contribute to dental caries that affects all ages of human being.

    OBJECTIVES: This study focuses on the potential of crude cell free supernatant (CCFS) from lactic acid bacteria (LAB) to inhibit of the growth of S. mutans UKMCC 1019.

    DESIGN: A total of 61 CCFS from LAB strains were screened for their inhibitory ability against S. mutans UKMCC 1019 by broth microdilution method. The selected LAB with highest antimicrobial activity was identified and its CCFS was characterized for pH stability, temperature tolerance, enzyme sensitivity, metabolism of carbohydrates, enzymatic activities and antimicrobial activity against S. mutans UKMCC 1019 and C. albicans UKMCC 3001 by well diffusion assay. The effect of CCFS on cell structure of S. mutans UKMCC 1019 was observed under transmission electron microscopy (TEM).

    RESULTS: The CCFS from isolate CC2 from Kimchi showed the highest inhibition against S. mutans UKMCC 1019, which was 76.46 % or 4406.08 mm2/mL and it was identified to be most closely related to Enterococcus faecium DSM 20477 based on 16 s rRNA sequencing. The CCFS of E. faecium DSM 20477 had high tolerance to acidic and alkaline environment as well as high temperature. It also shows high antifungal activities against C. albicans UKMCC 3001 with 2362.56 mm2/mL. Under TEM, the cell walls and the cytoplasm membrane of S. mutans UKMCC 1019 were disrupted by the antimicrobial substance, causing cell lysis.

    CONCLUSIONS: Hence, the CCFS from E. faecium DSM 20477 is a potential bacteriocin in future for the treatment of dental caries.

  9. Tam YJ, Allaudin ZN, Lila MA, Bahaman AR, Tan JS, Rezaei MA
    BMC Biotechnol, 2012;12:70.
    PMID: 23039947 DOI: 10.1186/1472-6750-12-70
    Cell disruption strategies by high pressure homogenizer for the release of recombinant Hepatitis B surface antigen (HBsAg) from Pichia pastoris expression cells were optimized using response surface methodology (RSM) based on the central composite design (CCD). The factors studied include number of passes, biomass concentration and pulse pressure. Polynomial models were used to correlate the above mentioned factors to project the cell disruption capability and specific protein release of HBsAg from P. pastoris cells.
  10. Abu Zarin M, Tan JS, Murugan P, Ahmad R
    BMC Complement Med Ther, 2020 Oct 19;20(1):317.
    PMID: 33076892 DOI: 10.1186/s12906-020-03113-0
    BACKGROUND: The banana or scientifically referred to as Musa sp., is one of the most popular fruits all over the world. Almost all parts of a banana tree, including the fruits, stem juice, and flowers are commonly used as traditional medicine for treating diarrhoea (unripe), menorrhagia, diabetes, dysentery, and antiulcerogenic, hypoglycemic, antilithic, hypolipidemic conditions, plus antioxidant actions, inflammation, pains and even snakebites. The study carried out was to evaluate in vitro anti-urolithiatic activity from different types of Musa pseudo-stems.

    METHODS: Observing anti-urolithiathic activity via in vitro nucleation and aggregation assay using a spectrophotometer followed by microscopic observation. A total of 12 methanolic extracts were tested to determine the potential extracts in anti-urolithiasis activities. Cystone was used as a positive control.

    RESULTS: The results manifested an inhibition of nucleation activity (0.11 ± 2.32% to 55.39 ± 1.01%) and an aggregation activity (4.34 ± 0.68% to 58.78 ± 1.81%) at 360 min of incubation time. The highest inhibition percentage in nucleation assay was obtained by the Musa acuminate x balbiciana Colla cv "Awak Legor" methanolic pseudo-stem extract (2D) which was 55.39 ± 1.01%at 60 min of incubation time compared to the cystone at 30.87 ± 0.74%. On the other hand,the Musa acuminate x balbiciana Colla cv "Awak Legor" methanolic bagasse extract (3D) had the highest inhibition percentage in the aggregation assay incubated at 360 min which was obtained at 58.78 ± 1.8%; 5.53% higher than the cystone (53.25%).The microscopic image showed a great reduction in the calcium oxalate (CaOx) crystals formation and the size of crystals in 2D and 3D extracts, respectively, as compared to negative control.

    CONCLUSIONS: The results obtained from this study suggest that the extracts are potential sources of alternative medicine for kidney stones disease.

  11. Abbasiliasi S, Tan JS, Ibrahim TA, Ramanan RN, Vakhshiteh F, Mustafa S, et al.
    BMC Microbiol, 2012;12:260.
    PMID: 23153191 DOI: 10.1186/1471-2180-12-260
    Lactic acid bacteria (LAB) can be isolated from traditional milk products. LAB that secrete substances that inhibit pathogenic bacteria and are resistant to acid, bile, and pepsin but not vancomycin may have potential in food applications.
  12. Abbasiliasi S, Tan JS, Bashokouh F, Ibrahim TAT, Mustafa S, Vakhshiteh F, et al.
    BMC Microbiol, 2017 May 23;17(1):121.
    PMID: 28535747 DOI: 10.1186/s12866-017-1000-z
    BACKGROUND: Selection of a microbial strain for the incorporation into food products requires in vitro and in vivo evaluations. A bacteriocin-producing lactic acid bacterium (LAB), Pediococcus acidilactici Kp10, isolated from a traditional dried curd was assessed in vitro for its beneficial properties as a potential probiotic and starter culture. The inhibitory spectra of the bacterial strain against different gram-positive and gram-negative bacteria, its cell surface hydrophobicity and resistance to phenol, its haemolytic, amylolytic and proteolytic activities, ability to produce acid and coagulate milk together with its enzymatic characteristics and adhesion property were all evaluated in vitro.

    RESULTS: P. acidilactici Kp10 was moderately tolerant to phenol and adhere to mammalian epithelial cells (Vero cells and ileal mucosal epithelium). The bacterium also exhibited antimicrobial activity against several gram-positive and gram-negative food-spoilage and food-borne pathogens such as Listeria monocytgenes ATCC 15313, Salmonella enterica ATCC 13311, Shigella sonnei ATCC 9290, Klebsiella oxytoca ATCC 13182, Enterobacter cloaca ATCC 35030 and Streptococcus pyogenes ATCC 12378. The absence of haemolytic activity and proteinase (trypsin) and the presence of a strong peptidase (leucine-arylamidase) and esterase-lipase (C4 and C8) were observed in this LAB strain. P. acidilactici Kp10 also produced acid, coagulated milk and has demonstrated proteolytic and amylolactic activities.

    CONCLUSION: The properties exhibited by P. acidilactici Kp10 suggested its potential application as probiotic and starter culture in the food industry.

  13. Tan JS, Abbasiliasi S, Kadkhodaei S, Tam YJ, Tang TK, Lee YY, et al.
    BMC Microbiol, 2018 01 04;18(1):3.
    PMID: 29439680 DOI: 10.1186/s12866-017-1145-9
    BACKGROUND: Demand for high-throughput bioprocessing has dramatically increased especially in the biopharmaceutical industry because the technologies are of vital importance to process optimization and media development. This can be efficiently boosted by using microtiter plate (MTP) cultivation setup embedded into an automated liquid-handling system. The objective of this study was to establish an automated microscale method for upstream and downstream bioprocessing of α-IFN2b production by recombinant Escherichia coli. The extraction performance of α-IFN2b by osmotic shock using two different systems, automated microscale platform and manual extraction in MTP was compared.

    RESULTS: The amount of α-IFN2b extracted using automated microscale platform (49.2 μg/L) was comparable to manual osmotic shock method (48.8 μg/L), but the standard deviation was 2 times lower as compared to manual osmotic shock method. Fermentation parameters in MTP involving inoculum size, agitation speed, working volume and induction profiling revealed that the fermentation conditions for the highest production of α-IFN2b (85.5 μg/L) was attained at inoculum size of 8%, working volume of 40% and agitation speed of 1000 rpm with induction at 4 h after the inoculation.

    CONCLUSION: Although the findings at MTP scale did not show perfect scalable results as compared to shake flask culture, but microscale technique development would serve as a convenient and low-cost solution in process optimization for recombinant protein.

  14. Hoe VC, Khairuddin A, Tan JS, Sharif MS, Azizan N, Hayati F
    BMC Surg, 2020 Jun 30;20(1):145.
    PMID: 32605613 DOI: 10.1186/s12893-020-00806-8
    BACKGROUND: Tuberculosis (TB) is classified according to the site of disease as pulmonary or extrapulmonary. Extrapulmonary TB is less common than its counterpart in which it can be found anywhere in the body including the liver. Similar to ampullary carcinoma, TB liver can manifest with jaundice and deranged liver function tests, particularly in the obstructed biliary systems.

    CASE PRESENTATION: A 43-year-old gentleman with locally advanced ampullary carcinoma was noticed to have multiple suspicious liver nodules intraoperatively during curative ampulla resection. The surgery was then abandoned after a biopsy. The histology was consistent with chronic granulomatous inflammation. He was then subjected to a Whipple pancreaticoduodenectomy procedure after initiation of anti-tubercular treatment. He recovered well with no evidence of tumour recurrence and worsening TB.

    CONCLUSIONS: A high index of suspicion and quick decision making can help to diagnose a possible extrapulmonary TB masquerading as a malignant disease in a patient with curative intention of ampullary carcinoma.

  15. Md Sidek NL, Halim M, Tan JS, Abbasiliasi S, Mustafa S, Ariff AB
    Biomed Res Int, 2018;2018:5973484.
    PMID: 30363649 DOI: 10.1155/2018/5973484
    Nowadays, bacteriocin industry has substantially grown replacing the role of chemical preservatives in enhancing shelf-life and safety of food. The progress in bacteriocin study has been supported by the emerging of consumer demand on the applications of natural food preservatives. Since food is a complex ecosystem, the characteristics of bacteriocin determine the effectiveness of their incorporation into the food products. Among four commercial media (M17 broth, MRS broth, tryptic soy broth, and nutrient broth) tested, the highest growth of Pediococcus acidilactici kp10 and bacteriocin-like-inhibitory substance (BLIS) production were obtained in the cultivation with M17. BLIS production was found to be a growth associated process where the production was increased concomitantly with the growth of producing strain, P. acidilactici kp10. The antimicrobial property of BLIS against three indicator microorganisms (Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus) remained stable upon heating at 100°C but not detectable at 121°C. The BLIS activity was also observed to be stable and active at a wide pH range (pH 2 to pH 7). The BLIS activity remained constant at -20°C and -80°C for 1 month of storage. However, the activity dropped after 3 and 6 months of storage at 4°C, -20°C, and -80°C with more than 80% reduction. The ability of bacteriocin from P. acidilactici kp10 to inhibit food-borne pathogens while remaining stable and active at extreme pH and temperature is of potential interest for future applications in food preservatives.
  16. Tan JS, Lee SY, Chew KW, Lam MK, Lim JW, Ho SH, et al.
    Bioengineered, 2020 12;11(1):116-129.
    PMID: 31909681 DOI: 10.1080/21655979.2020.1711626
    The richness of high-value bio-compounds derived from microalgae has made microalgae a promising and sustainable source of useful product. The present work starts with a review on the usage of open pond and photobioreactor in culturing various microalgae strains, followed by an in-depth evaluation on the common harvesting techniques used to collect microalgae from culture medium. The harvesting methods discussed include filtration, centrifugation, flocculation, and flotation. Additionally, the advanced extraction technologies using ionic liquids as extractive solvents applied to extract high-value bio-compounds such as lipids, carbohydrates, proteins, and other bioactive compounds from microalgae biomass are summarized and discussed. However, more work needs to be done to fully utilize the potential of microalgae biomass for the application in large-scale production of biofuels, food additives, and nutritive supplements.
  17. Abu Bakar MH, Tan JS
    Biomed Pharmacother, 2017 Sep;93:903-912.
    PMID: 28715871 DOI: 10.1016/j.biopha.2017.07.021
    Compelling evidences posited that high level of saturated fatty acid gives rise to mitochondrial dysfunction and inflammation in the development of insulin resistance in skeletal muscle. Celastrol is a pentacyclic triterpenoid derived from the root extracts of Tripterygium wilfordii that possesses potent anti-inflammatory properties in a number of animal models with metabolic diseases. However, the cellular mechanistic action of celastrol in alleviating obesity-induced insulin resistance in skeletal muscle remains largely unknown. Therefore, the present investigation evaluated the attributive properties of celastrol at different concentrations (10, 20, 30 and 40nM) on insulin resistance in C2C12 myotubes evoked by palmitate. We demonstrated that celastrol improved mitochondrial functions through significant enhancement of intracellular ATP content, mitochondrial membrane potential, citrate synthase activity and decrease of mitochondrial superoxide productions. Meanwhile, augmented mitochondrial DNA (mtDNA) content with suppressed DNA oxidative damage were observed following celastrol treatment. Celastrol significantly enhanced fatty acid oxidation rate and increased the level of tricarboxylic acid (TCA) cycle intermediates in palmitate-treated cells. Further analysis revealed that the improvement of glucose uptake activity in palmitate-loaded myotubes was partly mediated by celastrol via activation of PI3K-Akt insulin signaling pathway. Collectively, these findings provided evidence for the first time that the protection from palmitate-mediated insulin resistance in C2C12 myotubes by celastrol is likely associated with the improvement of mitochondrial functions-related metabolic activities.
  18. 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.
  19. Oslan SNH, Tan JS, Saad MZ, Halim M, Mohamed MS, Ariff AB
    Bioprocess Biosyst Eng, 2019 Mar;42(3):355-365.
    PMID: 30483888 DOI: 10.1007/s00449-018-2040-y
    Pasteurella multocida serotype B:2 is the causative agent of haemorrhagic septicaemia, a fatal disease in cattle and buffaloes. For use as a vaccine in the treatment of HS disease, an efficient cultivation of attenuated gdhA derivative P. multocida B:2 (mutant) for mass production of viable cells is required. In this study, the role of amino acids and vitamins on the growth of this particular bacterium was investigated. Initially, three basal media (Brain-heart infusion, Terrific broth, and defined medium YDB) were assessed in terms of growth performance of P. multocida B:2. YDB medium was selected and redesigned to take into account the effects of amino acids (glutamic acid, cysteine, glycine, methionine, lysine, tyrosine, and histidine) and vitamins (vitamin B1, nicotinic acid, riboflavin, pyridoxine, pantothenic acid, and biotin). High viable cell number was largely affected by the availability of micronutrient components and macronutrients. Histidine was essential for the growth whereby a traceable amount (20 mM) was found to greatly enhance the growth of gdhA derivative P. multocida B:2 mutant (6.6 × 109 cfu/mL) by about 19 times as compared to control culture (3.5 × 108 cfu/mL). In addition, amongst the vitamins added, riboflavin exhibited the highest impact on the viability of gdhA derivative P. multocida B:2 mutant (5.3 × 109 cfu/mL). Though the combined histidine and riboflavin in the culture eventually did not promote the stacking impact on cell growth and cell viability, nonetheless, they were still essential and important in either growth medium or production medium.
  20. Ng HS, Ooi CW, Mokhtar MN, Show PL, Ariff A, Tan JS, et al.
    Bioresour Technol, 2013 Aug;142:723-6.
    PMID: 23806510 DOI: 10.1016/j.biortech.2013.05.087
    An extractive bioconversion with Bacillus cereus cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) in aqueous two-phase system (ATPS) was investigated for the synthesis and recovery of cyclodextrins (CDs). Optimum condition for the extractive bioconversion of CDs was achieved in ATPS consisted of 7.7% (w/w) polyethylene glycol (PEG) 20,000 and 10.3% (w/w) dextran T500 with volume ratio (VR) of 4.0. Enzymatic conversion of starch occurred mainly in dextran-rich bottom phase whereas the product, CDs was transferred to top phase and a higher partition coefficient of CDs was achieved. Repetitive batch of CDs synthesis was employed by replenishment of the top phase components and addition of starch every 8h. An average total CDs concentration of 13.7 mg/mL, (4.77 mg/mLα-CD, 5.02 mg/mLβ-CD and 3.91 mg/mLγ-CD) was recovered in the top phase of PEG 20,000/dextran T500 ATPS. This study showed the effectiveness of ATPS application in extractive bioconversion of CDs synthesis with B. cereus CGTase.
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