Displaying publications 1 - 20 of 85 in total

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  1. Design and optimization of a probiotic tablet for gastrointestinal tolerance by a simplex-centroid mixture
    Azhar MA, Munaim MSA
    Drug Dev Ind Pharm, 2021 Feb;47(2):189-196.
    PMID: 33290104 DOI: 10.1080/03639045.2020.1862176
    In this study, a simplex-centroid mixture design using design of experiment (DOE) software was implemented to evaluate the effect of biopolymers as excipients, which are hydroxypropyl methylcellulose, and alginate, on the gastrointestinal tolerance of probiotic tablet containing Saccharomyces boulardii. Microbial viability and dissolution time were used to evaluate the ideal formulation made using 39.01% carboxymethylcellulose and 60.99% alginate as excipients, which protected the probiotics from the acidic condition in the stomach with good dissolution time. The formulated probiotic tablet is more stable in terms of viability when stored at 4 °C compared to room temperature. However, the viability remains above 106 CFU/tablet after six months of storage at room temperature. This study shows that the simplex-centroid mixture design is valid and can be used to formulate probiotic tablets that possess gastrointestinal tolerance. This study can lead to the development of commercial production of probiotic yeast tablets with gastrointestinal tolerance.
    Matched MeSH terms: Microbial Viability
  2. Proton-Functionalized Graphitic Carbon Nitride for Efficient Metal-Free Destruction of Escherichia coli under Low-Power Light Irradiation
    Ng BJ, Musyaffa MK, Er CC, Packiam KAR, Lee WPC, Tan LL, et al.
    Chemistry, 2021 Feb 10;27(9):3085-3090.
    PMID: 33263935 DOI: 10.1002/chem.202004238
    Universal access to clean water has been a global ambition over the years. Photocatalytic water disinfection through advanced oxidation processes has been regarded as one of the promising methods for breaking down microbials. The forefront of this research focuses on the application of metal-free photocatalysts for disinfection to prevent secondary pollution. Graphitic carbon nitride (g-C3 N4 ) has achieved instant attention as a metal-free and visible-light-responsive photocatalyst for various energy and environmental applications. However, the photocatalytic efficiency of g-C3 N4 is still affected by its rapid charge recombination and sluggish electron-transfer kinetics. In this contribution, two-dimensionally protonated g-C3 N4 was employed as metal-free photocatalyst for water treatment and demonstrated 100 % of Escherichia coli within 4 h under irradiation with a 23 W light bulb. The introduction of protonation can modulate the surface charge of g-C3 N4 ; this enhances its conductivity and provides a "highway" for the delocalization of electrons. This work highlights the potential of conjugated polymers in antibacterial application.
    Matched MeSH terms: Microbial Viability/drug effects; Microbial Viability/radiation effects*
  3. Escherichia coli tolerance of ultraviolet radiation by in vivo expression of a short peptide designed from late embryogenesis abundant protein
    Huwaidi A, Pathak N, Syahir A, Ikeno S
    Biochem Biophys Res Commun, 2018 09 05;503(2):910-914.
    PMID: 29928878 DOI: 10.1016/j.bbrc.2018.06.095
    Ultraviolet (UV) radiation causes damage in all living organisms, including DNA damage that leads to cell death. Herein, we provide a new technique for UV radiation protection through intracellular short peptide expression. The late embryogenesis abundant (LEA) peptide, which functions as a shield that protects macromolecules from various abiotic stress, was obtained from the Polypedilum vanderplanki group 3 LEA protein. Recombinant Escherichia coli BL21 (DE3) expressing functional LEA short peptide in vivo were exposed to UVA and UVC radiation for 4, 6, and 8 h. E. coli transformants expressing the LEA peptide showed higher cell viability under both UVA and UVC treatment at all time points as compared with that of the control. Furthermore, the cells expressing LEA peptide showed a higher number of colony-forming units per dilution under UVA and UVC treatment. These results suggested that expression of the short peptide could be useful for the development of genetically modified organisms and in applications that require resilience of organisms to UV radiation.
    Matched MeSH terms: Microbial Viability/genetics; Microbial Viability/radiation effects
  4. A standard quantitative method to measure acid tolerance of probiotic cells
    Chan ES, Lee PP, Ravindra P, Krishnaiah K, Voo WP
    Appl Microbiol Biotechnol, 2010 Mar;86(1):385-91.
    PMID: 20033402 DOI: 10.1007/s00253-009-2384-y
    The aim of this work was to develop a standard quantitative method to measure the acid tolerance of probiotic cells when exposed to a simulated gastric fluid. Three model strains of different cell concentrations were exposed to a standard simulated gastric fluid of fixed volume. The fluid pH ranged from pH 1.5 to 2.5. In general, the death kinetics followed an exponential trend. The overall death constant, k (d), for all strains was found to be in a power relationship with the pH value and the initial cell concentration, and it can be expressed as k(d)=k(AII) (pH(-9.0)N(0)(-0.19)) where k (AII) is defined as the acid intolerance indicator and N (0) is the initial cell concentration (CFU/ml). This equation was validated with the experimental data with an average R (2) of 0.98. The acid intolerance of cells can be quantitatively expressed by the k (AII) values, where higher value indicates higher intolerance. In conclusion, a standard quantitative method has been developed to measure the acid tolerance of probiotic cells. This could facilitate the selection of probiotic strains and processing technologies.
    Matched MeSH terms: Microbial Viability
  5. Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology
    Hossain MS, Nik Ab Rahman NN, Balakrishnan V, Alkarkhi AF, Ahmad Rajion Z, Ab Kadir MO
    Waste Manag, 2015 Apr;38:462-73.
    PMID: 25636860 DOI: 10.1016/j.wasman.2015.01.003
    Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO2) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO2 sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO2-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO2 exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials.
    Matched MeSH terms: Microbial Viability/drug effects*
  6. Effect of electroporation on bioconversion of isoflavones and probiotic properties of parents and subsequent passages of Bifidobacterium longum
    Yeo SK, Ong JS, Liong MT
    Appl Biochem Biotechnol, 2014 Oct;174(4):1496-1509.
    PMID: 25119552 DOI: 10.1007/s12010-014-1141-6
    This study aimed to evaluate the effects of electroporation on growth, bioconversion of isoflavones, and probiotic properties of parent organisms and subsequent passages of Bifidobacterium longum FTDC 8643. Electroporation with the strength of electric field at 7.5 kV cm(-1) for 3.5 ms was applied on B. longum FTDC 8643. The viability of B. longum FTDC 8643 increased significantly upon treatment with electroporation. Such treatment also enhanced the intracellular and extracellular β-glucosidase activity, leading to enhanced production of bioactive isoflavone aglycones in mannitol-soymilk (P 
    Matched MeSH terms: Microbial Viability/drug effects
  7. Fulltext Molecular characterization of putative virulence determinants in Burkholderia pseudomallei
    Puah SM, Puthucheary SD, Wang JT, Pan YJ, Chua KH
    ScientificWorldJournal, 2014;2014:590803.
    PMID: 25215325 DOI: 10.1155/2014/590803
    The Gram-negative saprophyte Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease which is endemic in Southeast Asia and northern Australia. This bacterium possesses many virulence factors which are thought to contribute to its survival and pathogenicity. Using a virulent clinical isolate of B. pseudomallei and an attenuated strain of the same B. pseudomallei isolate, 6 genes BPSL2033, BP1026B_I2784, BP1026B_I2780, BURPS1106A_A0094, BURPS1106A_1131, and BURPS1710A_1419 were identified earlier by PCR-based subtractive hybridization. These genes were extensively characterized at the molecular level, together with an additional gene BPSL3147 that had been identified by other investigators. Through a reverse genetic approach, single-gene knockout mutants were successfully constructed by using site-specific insertion mutagenesis and were confirmed by PCR. BPSL2033::Km and BURPS1710A_1419::Km mutants showed reduced rates of survival inside macrophage RAW 264.7 cells and also low levels of virulence in the nematode infection model. BPSL2033::Km demonstrated weak statistical significance (P = 0.049) at 8 hours after infection in macrophage infection study but this was not seen in BURPS1710A_1419::Km. Nevertheless, complemented strains of both genes were able to partially restore the gene defects in both in vitro and in vivo studies, thus suggesting that they individually play a minor role in the virulence of B. pseudomallei.
    Matched MeSH terms: Microbial Viability/genetics
  8. The survival of influenza A(H1N1)pdm09 virus on 4 household surfaces
    Oxford J, Berezin EN, Courvalin P, Dwyer DE, Exner M, Jana LA, et al.
    Am J Infect Control, 2014 Apr;42(4):423-5.
    PMID: 24679569 DOI: 10.1016/j.ajic.2013.10.016
    We investigated the survival of a pandemic strain of influenza A H1N1 on a variety of common household surfaces where multiple samples were taken from 4 types of common household fomite at 7 time points. Results showed that influenza A H1N1sw virus particles remained infectious for 48 hours on a wooden surface, for 24 hours on stainless steel and plastic surfaces, and for 8 hours on a cloth surface, although virus recovery from the cloth may have been suboptimal. Our results suggest that pandemic influenza A H1N1 can survive on common household fomites for extended periods of time, and that good hand hygiene and regular disinfection of commonly touched surfaces should be practiced during the influenza season to help reduce transmission.
    Matched MeSH terms: Microbial Viability*
  9. Effects of encapsulation on the viability of potential probiotic Lactobacillus plantarum exposed to high acidity condition and presence of bile salts
    Tee WF, Nazaruddin R, Tan YN, Ayob MK
    Food Sci Technol Int, 2014 Sep;20(6):399-404.
    PMID: 23774606 DOI: 10.1177/1082013213488775
    This study investigated the survival of encapsulated potential probiotic Lactobacillus plantarum which isolated from fermented cocoa beans. κ-Carrageenan was used to encapsulate the probiotic. Encapsulation techniques such as emulsification, freeze-drying or extrusion were adopted to encapsulate the probiotic. Freeze-drying and extrusion methods showed higher (p 
    Matched MeSH terms: Microbial Viability/drug effects*
  10. Comparison of Fe(VI) (FeO4(2-)) and ozone in inactivating Bacillus subtilis spores
    Makky EA, Park GS, Choi IW, Cho SI, Kim H
    Chemosphere, 2011 May;83(9):1228-33.
    PMID: 21489600 DOI: 10.1016/j.chemosphere.2011.03.030
    The protozoan parasites such as Cryptosporidiumparvum and Giardialamblia have been recognized as a frequent cause of recent waterborne disease outbreaks because of their strong resistance against chlorine disinfection. In this study, ozone and Fe(VI) (i.e., FeO(4)(2-)) were compared in terms of inactivation efficiency for Bacillus subtilis spores which are commonly utilized as an indicator of protozoan pathogens. Both oxidants highly depended on water pH and temperature in the spore inactivation. Since redox potential of Fe(VI) is almost the same as that of ozone, spore inactivation efficiency of Fe(VI) was expected to be similar with that of ozone. However, it was found that ozone was definitely superior over Fe(VI): at pH 7 and 20°C, ozone with the product of concentration×contact time (C¯T) of 10mgL(-1)min inactivate the spores more than 99.9% within 10min, while Fe(VI) with C¯T of 30mgL(-1) min could inactivate 90% spores. The large difference between ozone and Fe(VI) in spore inactivation was attributed mainly to Fe(III) produced from Fe(VI) decomposition at the spore coat layer which might coagulate spores and make it difficult for free Fe(VI) to attack live spores.
    Matched MeSH terms: Microbial Viability/drug effects*
  11. Development of probiotic carriers using microbial transglutaminase-crosslinked soy protein isolate incorporated with agrowastes
    Lew LC, Bhat R, Easa AM, Liong MT
    J Sci Food Agric, 2011 Jun;91(8):1406-15.
    PMID: 21384373 DOI: 10.1002/jsfa.4325
    Probiotics are live micro-organisms that exert beneficial effects on their host. A high survival rate during gastrointestinal transit and storage is often desirable. The main aim of this study was to develop protective carriers for probiotics via the use of enzymatically crosslinked soy protein isolate incorporated with agrowastes such as banana peel, banana pulp, cempedak rind and cocoa rind.
    Matched MeSH terms: Microbial Viability*
  12. A prospective study of mycobacterial viability in refrigerated, unpreserved sputum batched for up to 8 weeks
    Rashid Ali MR, Parameswaran U, William T, Bird E, Wilkes CS, Lee WK, et al.
    Int J Tuberc Lung Dis, 2015 May;19(5):620-1.
    PMID: 25868033 DOI: 10.5588/ijtld.14.0938
    Matched MeSH terms: Microbial Viability*
  13. Influence of freeze-drying and spray-drying preservation methods on survivability rate of different types of protectants encapsulated Lactobacillus acidophilus FTDC 3081
    Tang HW, Abbasiliasi S, Murugan P, Tam YJ, Ng HS, Tan JS
    Biosci Biotechnol Biochem, 2020 Sep;84(9):1913-1920.
    PMID: 32448058 DOI: 10.1080/09168451.2020.1770572
    The aims of this study were to compare the effectiveness of different drying methods and to investigate the effects of adding a series of individual protectant such as skim milk, sucrose, maltodextrin, and corn starch for preserving Lactobacillus acidophilus FTDC 3081 cells during spray and freeze-drying and storage at different temperatures. Results showed a remarkable high survival rate of 70-80% immediately after spray- and freeze-drying in which the cell viability retained at the range of 109 to 1010 CFU/mL. After a month of storage, maltodextrin showed higher protective ability on both spray- and freeze-dried cells as compared to other protective agents at 4°C, 25°C, and 40°C. A complete loss in viability of spray-dried L. acidophilus FTDC 3081 was observed after a month at 40°C in the absence of protective agent.
    Matched MeSH terms: Microbial Viability/drug effects*
  14. Fulltext Antimycotic Activity of Seaweed Extracts（ Caulerpa lentillifera and Eucheuma cottonii） against Two Genera of Marine Oomycetes, Lagenidium spp. and Haliphthoros spp
    Saito H, Tamrin ML
    Biocontrol Sci, 2019;24(2):73-80.
    PMID: 31204358 DOI: 10.4265/bio.24.73
    Fungal infection mostly caused by marine oomycetes had hindered crustacean production thus searching for natural and safe treatment is currently needed. Thus, this study was conducted to investigate the antimycotic effect of different seaweed extract against marine oomycetes (Lagenidium spp. and Haliphthoros spp) . Two seaweeds species (Eucheuma cottonii and Caulerpa lentillifera) were extracted using ethanol, methanol and water. Each extracts was tested on four fungi strains of marine oomycetes species for minimum inhibitory concentration (MIC) and fungicidal activities. C. lentillifera ethanol extract showed the highest antifungal effect where it can inhibit three from four fungal strains. Meanwhile, E. cottonii ethanol extract has lowest MIC (500 ppm) and inhibit L. thermophilum IPMB 1401 and H. sabahensis IPMB 1402 hyphal growths. Antimycotic effect on zoospores production shows reduction in production after 12 h immersion for three marine oomycetes species. Seaweed extracts toxicity on Artemia sp. showed approximately 5% mortality at 12 h immersion. It is suggested that 12 h immersion of seaweed extract is a suitable treatment for marine oomycetes in aquaculture. This study does not only show potential alternative control method for crab larvae health management, it may also contribute to the sustainable development and food security of aquaculture industry.
    Matched MeSH terms: Microbial Viability/drug effects
  15. Cell viability of microencapsulated Bifidobacterium animalis subsp. lactis under freeze-drying, storage and gastrointestinal tract simulation conditions
    Shamekhi F, Shuhaimi M, Ariff A, Manap YA
    Folia Microbiol (Praha), 2013 Mar;58(2):91-101.
    PMID: 22843029 DOI: 10.1007/s12223-012-0183-9
    The purpose of this study was to improve the survival of Bifidobacterium animalis subsp. lactis 10140 during freeze-drying process by microencapsulation, using a special pediatric prebiotics mixture (galactooligosaccharides and fructooligosaccharides). Probiotic microorganisms were encapsulated with a coat combination of prebiotics-calcium-alginate prior to freeze-drying. Both encapsulated and free cells were then freeze-dried in their optimized combinations of skim milk and prebiotics. Response surface methodology (RSM) was used to produce a coating combination as well as drying medium with the highest cell viability during freeze-drying. The optimum encapsulation composition was found to be 2.1 % Na-alginate, 2.9 % prebiotic, and 21.7 % glycerol. Maximum survival predicted by the model was 81.2 %. No significant (p > 0.05) difference between the predicted and experimental values verified the adequacy of final reduced models. The protection ability of encapsulation was then examined over 120 days of storage at 4 and 25 °C and exposure to a sequential model of infantile GIT conditions including both gastric conditions (pH 3.0 and 4.0, 90 min, 37 °C) and intestinal conditions (pH 7.5, 5 h, 37 °C). Significantly improved cell viability showed that microencapsulation of B. lactis 10140 with the prebiotics was successful in producing a stable symbiotic powdery nutraceutical.
    Matched MeSH terms: Microbial Viability/radiation effects*
  16. Enhancement of biodegradation of crude petroleum-oil in contaminated water by the addition of nitrogen sources
    Mukred AM, Hamid AA, Hamzah A, Yusoff WM
    Pak J Biol Sci, 2008 Sep 01;11(17):2122-7.
    PMID: 19266926
    Addition of nitrogen sources as supplementary nutrient into MSM medium to enhance biodegradation by stimulating the growth four isolates, Acinetobacter faecalis, Staphylococcus sp., Pseudomonas putida and Neisseria elongata isolated from petroleum contaminated groundwater, wastewater aeration pond and biopond at the oil refinery Terengganu Malaysia was investigated. The organic nitrogen sources tested not only supported growth but also enhances biodegradation of 1% Tapis crude oil. All four isolates showed good growth especially when peptone was employed as the organic nitrogen compared to growth in the basal medium. Gas chromatography showed that more then 91, 93, 94 and 95% degradation of total hydrocarbon was observed after 5 days of incubation by isolates Pseudomonas putida, Neisseria elongate, Acinetobacter faecalis and Staphylococcus sp., respectively.
    Matched MeSH terms: Microbial Viability/drug effects
  17. Improved production of live cells of Lactobacillus rhamnosus by continuous cultivation using glucose-yeast extract medium
    Ling LS, Mohamad R, Rahim RA, Wan HY, Ariff AB
    J Microbiol, 2006 Aug;44(4):439-46.
    PMID: 16953180
    In this study, the growth kinetics of Lactobacillus rhamnosus and lactic acid production in continuous culture were assessed at a range of dilution rates (0.05 h(-1) to 0.40 h(-1)) using a 2 L stirred tank fermenter with a working volume of 600 ml. Unstructured models, predicated on the Monod and Luedeking-Piret equations, were employed to simulate the growth of the bacterium, glucose consumption, and lactic acid production at different dilution rates in continuous cultures. The maximum specific growth rate of L. rhamnosus, mu-max, was estimated at 0.40 h(-1), and the Monod cell growth saturation constant, Ks, at approximately 0.25 g/L. Maximum cell viability (1.3 x 10(10) CFU/ml) was achieved in the dilution rate range of D = 0.28 h(-1) to 0.35 h(-1). Both maximum viable cell yield and productivity were achieved at D = 0.35 h(-1). The continuous cultivation of L. rhamnosus at D = 0.35 h(-1) resulted in substantial improvements in cell productivity, of 267% (viable cell count) that achieved via batch cultivation.
    Matched MeSH terms: Microbial Viability
  18. Fulltext Nematode Peptides with Host-Directed Anti-inflammatory Activity Rescue Caenorhabditis elegans from a Burkholderia pseudomallei Infection
    Lim MP, Firdaus-Raih M, Nathan S
    Front Microbiol, 2016;7:1436.
    PMID: 27672387 DOI: 10.3389/fmicb.2016.01436
    Burkholderia pseudomallei, the causative agent of melioidosis, is among a growing number of bacterial pathogens that are increasingly antibiotic resistant. Antimicrobial peptides (AMPs) have been investigated as an alternative approach to treat microbial infections, as generally, there is a lower likelihood that a pathogen will develop resistance to AMPs. In this study, 36 candidate Caenorhabditis elegans genes that encode secreted peptides of <150 amino acids and previously shown to be overexpressed during infection by B. pseudomallei were identified from the expression profile of infected nematodes. RNA interference (RNAi)-based knockdown of 12/34 peptide-encoding genes resulted in enhanced nematode susceptibility to B. pseudomallei without affecting worm fitness. A microdilution test demonstrated that two peptides, NLP-31 and Y43C5A.3, exhibited anti-B. pseudomallei activity in a dose dependent manner on different pathogens. Time kill analysis proposed that these peptides were bacteriostatic against B. pseudomallei at concentrations up to 8× MIC90. The SYTOX green assay demonstrated that NLP-31 and Y43C5A.3 did not disrupt the B. pseudomallei membrane. Instead, gel retardation assays revealed that both peptides were able to bind to DNA and interfere with bacterial viability. In parallel, microscopic examination showed induction of cellular filamentation, a hallmark of DNA synthesis inhibition, of NLP-31 and Y43C5A.3 treated cells. In addition, the peptides also regulated the expression of inflammatory cytokines in B. pseudomallei infected macrophage cells. Collectively, these findings demonstrate the potential of NLP-31 and Y43C5A.3 as anti-B. pseudomallei peptides based on their function as immune modulators.
    Matched MeSH terms: Microbial Viability
  19. Comparison of microplate- and bottle-based methods to age yeast for chronological life span assays
    Kwong MMY, Lee JW, Samian MR, Watanabe N, Osada H, Ong EBB
    J Microbiol Methods, 2019 12;167:105743.
    PMID: 31629019 DOI: 10.1016/j.mimet.2019.105743
    This study compared the chronological life span and survival of Saccharomyces cerevisiae aged in a microplate or bottle, under different aeration and calorie restriction conditions. Our data shows that limited aeration in the microplate-aged culture contributed to slower outgrowth but extended yeast CLS compared to the bottle-aged culture.
    Matched MeSH terms: Microbial Viability
  20. Microencapsulation of Lactobacillus rhamnosus GG with flaxseed mucilage using co-extrusion technique
    Lai K, How Y, Pui L
    J Microencapsul, 2021 Mar;38(2):134-148.
    PMID: 33306440 DOI: 10.1080/02652048.2020.1863490
    AIM: This study aimed to evaluate the protective effect of flaxseed mucilage on the co-extrusion microencapsulation of Lactobacillus rhamnosus GG.

    METHODS: Core flow rate, chitosan coating, and flaxseed mucilage concentration were optimised for the microencapsulation of L. rhamnosus. The microbeads were characterised and evaluated on microencapsulation efficiency and cell released after 6 h of sequential digestion.

    RESULTS: The optimised parameters for the L. rhamnosus microencapsulation were 1.0 mL/min core flow rate, 0.4% (w/v) chitosan coating, and 0.4% (w/v) flaxseed mucilage. The L. rhamnosus microbeads with flaxseed mucilage in core and wall materials had a smooth surface with 781.3 µm diameter, the highest microencapsulation efficiency (98.8% w/w), lowest swelling (5196.7% w/w) and erosion ratio (515.5% w/w), and least cell release (<40% w/w) with 9.31 log10 CFU mL-1 after sequential digestion.

    CONCLUSIONS: This study showed the protective capacity of flaxseed mucilage towards the L. rhamnosus GG during microencapsulation and gastrointestinal environment.

    Matched MeSH terms: Microbial Viability
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