Displaying publications 81 - 100 of 379 in total

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  1. Physicochemical characteristics of microbial content in a modified anaerobic inclining-baffled reactor (MAI-BR) treating recycled paper mill effluent (RPME)
    Zwain HM, Chang SM, Dahlan I
    Prep Biochem Biotechnol, 2019;49(4):344-351.
    PMID: 30712465 DOI: 10.1080/10826068.2019.1566144
    Microbial content formed in bioreactors plays a significant role in the anaerobic process. Therefore, the physicochemical characteristics of microbial content in a modified anaerobic inclining-baffled reactor (MAI-BR) treating recycled paper mill effluent (RPME) were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG), and derivative thermogravimetric (DTG) analyses, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Brunauer-Emmett-Teller (BET), and surface area analyzer. FTIR spectra revealed that the microbial content had stronger characteristic peaks corresponding to alcohols, water, lipids carbohydrates, proteins, and mineral compounds. Calcite, muscovite, and lepidolite were the prevalent mineral phases found by XRD analysis. The elemental of these minerals like C, Ca, N, O, and Si was confirmed by XPS results. The microbial content samples from each compartment showed similar thermal behavior. SEM images showed that straight rod-shaped and Methanosaeta-like microorganisms were predominant, whereas C, O, and Ca were noticed by EDS on the surface of granules. The BET surface areas and pores of granules are found to decline throughout the reactor's compartment, where Compartment 1 had the largest values. Thus, the findings of this study establish further understanding of the physicochemical properties of microbial content formed in MAI-BR during the RPME treatment.
    Matched MeSH terms: Bioreactors
  2. Evaluation of recycled paper mill effluent digestion in a modified anaerobic hybrid baffled (MAHB) reactor: reactor performance & kinetic studies
    Hassan SR, Zaman NQ, Dahlan I
    Prep Biochem Biotechnol, 2020;50(3):234-239.
    PMID: 31762367 DOI: 10.1080/10826068.2019.1692214
    Recycled paper mill effluent (RPME) consists of various organic and inorganic compounds. In this study, modified anaerobic hybrid baffled (MAHB) bioreactor has been successfully used to anaerobically digest RPME. The anaerobic digestion was investigated in relation to methane production rate, lignin removal, and chemical oxygen demand (COD) removal, with respect to organic loading rate (OLR) and hydraulic retention time (HRT). The analysis using kinetic study was carried out under mesophilic conditions (37 ± 2 °C) and influent COD concentrations (1000-4000 mg L-1), to prove its practicability towards RPME treatment. First-order kinetic model was used to clarify the behavior of RPME anaerobic digestion under different OLRs (0.14-4.00 g COD L-1 d-1) and HRT (1-7 d). The result shows that the highest COD removal efficiency and methane production rate were recorded to be 98.07% and 2.2223 L CH4 d-1, respectively. This result was further validated by evaluating the biokinetic coefficients (reaction rate constant (k) and maximum biogas production (ym)), which gave values of k = 0.57 d-1 and ym = 0.331 L d-1. This kinetic data concludes that MAHB presented satisfactory performance towards COD removal with relatively high methane production, which can be further utilized as on-site energy supply.
    Matched MeSH terms: Bioreactors*
  3. Fulltext Patterned Membrane in an Energy-Efficient Tilted Panel Filtration System for Fouling Control in Activated Sludge Filtration
    Osman A, Mat Nawi NI, Samsuri S, Bilad MR, Shamsuddin N, Khan AL, et al.
    Polymers (Basel), 2020 Feb 12;12(2).
    PMID: 32059397 DOI: 10.3390/polym12020432
    A membrane bioreactor enhances the overall biological performance of a conventional activated sludge system for wastewater treatment by producing high-quality effluent suitable for reuse. However, membrane fouling hinders the widespread application of membrane bioreactors by reducing the hydraulic performance, shortening membrane lifespan, and increasing the operational costs for membrane fouling management. This study assesses the combined effect of membrane surface corrugation and a tilted panel in enhancing the impact of air bubbling for membrane fouling control in activated sludge filtration, applicable for membrane bioreactors. The filterability performance of such a system was further tested under variable parameters: Filtration cycle, aeration rate, and intermittent aeration. Results show that a combination of surface corrugation and panel tilting enhances the impact of aeration and leads to 87% permeance increment. The results of the parametric study shows that the highest permeance was achieved under short filtration-relaxation cycle of 5 min, high aeration rate of 1.5 L/min, and short switching period of 2.5 min, to yield the permeances of 465 ± 18, 447 ± 2, and 369 ± 9 L/(m2h bar), respectively. The high permeances lead to higher operational flux that helps to lower the membrane area as well as energy consumption. Initial estimation of the fully aerated system yields the energy input of 0.152 kWh/m3, much lower than data from the full-scale references of <0.4 kWh/m3. Further energy savings and a lower system footprint can still be achieved by applying the two-sided panel with a switching system, which will be addressed in the future.
    Matched MeSH terms: Bioreactors
  4. Fulltext Enhanced biocatalytic esterification with lipase-immobilized chitosan/graphene oxide beads
    Lau SC, Lim HN, Basri M, Fard Masoumi HR, Ahmad Tajudin A, Huang NM, et al.
    PLoS One, 2014;9(8):e104695.
    PMID: 25127038 DOI: 10.1371/journal.pone.0104695
    In this work, lipase from Candida rugosa was immobilized onto chitosan/graphene oxide beads. This was to provide an enzyme-immobilizing carrier with excellent enzyme immobilization activity for an enzyme group requiring hydrophilicity on the immobilizing carrier. In addition, this work involved a process for the preparation of an enzymatically active product insoluble in a reaction medium consisting of lauric acid and oleyl alcohol as reactants and hexane as a solvent. This product enabled the stability of the enzyme under the working conditions and allowed the enzyme to be readily isolated from the support. In particular, this meant that an enzymatic reaction could be stopped by the simple mechanical separation of the "insoluble" enzyme from the reaction medium. Chitosan was incorporated with graphene oxide because the latter was able to enhance the physical strength of the chitosan beads by its superior mechanical integrity and low thermal conductivity. The X-ray diffraction pattern showed that the graphene oxide was successfully embedded within the structure of the chitosan. Further, the lipase incorporation on the beads was confirmed by a thermo-gravimetric analysis. The lipase immobilization on the beads involved the functionalization with coupling agents, N-hydroxysulfosuccinimide sodium (NHS) and 1-ethyl-(3-dimethylaminopropyl) carbodiimide (EDC), and it possessed a high enzyme activity of 64 U. The overall esterification conversion of the prepared product was 78% at 60 °C, and it attained conversions of 98% and 88% with commercially available lipozyme and novozyme, respectively, under similar experimental conditions.
    Matched MeSH terms: Bioreactors*
  5. Fulltext Repeated fed-batch cultivation of nitrogen-fixing bacterium, bacillus sphaericus UPMB10, using glycerol as the carbon source
    Ariff, A.B., Ooi, T.C., Shamsuddin, Z.H., Halimi, M.S.
    Pertanika Journal of Science & Technology, 2010;18(2):-.
    MyJurnal
    The exponential fed-batch cultivation of Bacillus sphaericus UPMB10 in 2 l stirred tank fermenter was performed by feeding the initial batch culture with 14 g l-1 of glycerol according to the algorithm aimed at controlling the specific growth rate (μ) of the bacterium. Very high viable cell count (1.14 x 1010 cfu ml-1), which was four times higher as compared to batch cultivation, was achieved in the fed-batch with a controlled μ at 0.4 h-1. In repeated exponential fed-batch cultivation, consisting of four cycles of harvesting and recharging, a final cell concentration of 1.9 x 1011 cfu ml-1 was obtained at the end of the fourth cycle (46 h). Meanwhile, acetylene reduction of cell samples collected from repeated fed-batch cultivation remained unchanged and was maintained at around 20 nmol C2H2 h-1 ml-1 after prolonged cultivation period, and was comparable to those obtained in batch and exponential fed-batch cultivation. Glycerol could be used as a carbon source for high performance cultivation of B. sphaericus, a nitrogen fixing bacterium, in repeated fed-batch cultivation with high cell yield and cell productivity. The productivity (0.68 g l-1 h-1) for repeated fed-batch cultivation increased about 6 times compared to that obtained in conventional batch cultivation (0.11 g l1 h-1). A innovative method in utilizing glycerol for efficient cultivation of nitrogen fixing bacterium could be beneficial to get more understanding and reference in manipulating the integrated plans for sustainable and profitable biodiesel industry.
    Matched MeSH terms: Bioreactors
  6. Fulltext Overliming effects on xylitol production from sago trunk hydrolysate
    Mohamad, N.L., Mustapa Kamal, S.M., Abdullah, A.G.L.
    Pertanika Journal of Science & Technology, 2011;19(2):415-422.
    MyJurnal
    Xylitol can be obtained from lignocellulosic materials containing xylose. However, the fraction of lignocellulose converted through dilute acid hydrolysis contains compounds that inhibit the fermenting micro-organisms. These inhibitors can be removed from the hydrolysate by detoxification method, prior to fermentation. This study describes effectiveness of overliming process to reduce the toxicity of hydrolysates generated from pre-treatment of sago trunk for xylitol production. The overliming pH 9 and 10 was studied and the results showed that pH 9 was showed 20% of sugar loss, which is low compared to pH 10. Candida tropicalis strain was used to evaluate the fermentability of overlimed sago trunk hydrolysate at pH 9 and non-overlimed hydrolysate medium. Meanwhile, Xylitol accumulation and productivity in the overlimed medium was found to be higher than the non-treated medium. The maximum production of xylitol was increased up to 74% and converted within 76 h. The results obtained improved the fermentation process when compared with the nontreated medium.
    Matched MeSH terms: Bioreactors
  7. Fulltext Optimization and analysis of bioethanol production from cassava starch hydrolysis
    Liew, E. W. T.
    Pertanika Journal of Science & Technology, 2014;22(2):637-644.
    MyJurnal
    Current ethanol production processes utilizing crops such as sugar cane and corn starch have been well established over the decade. Other crop such as cassava is a potential candidate in producing ethanol. However, thermal processes are required to hydrolyze starch for the production of fermentable sugars. The processes are energy intensive and could lead to undesirable by-products generation. In this work, the hydrolysis of cassava starch is studied following an experimental design as a statistical problem solving approach. Central composite design (CCD) is used in order to select the most important variables from the simultaneous study on the effect and influence of operating conditions of bioreactor utilized, namely, pH, temperature and substrate concentration, as well as to optimize the process of cassava starch hydrolysis. From the results obtained, it can be concluded that the cassava starch hydrolysis is enhanced by pH and temperature. Model validations show good agreement between experimental results and the predicted responses.
    Matched MeSH terms: Bioreactors
  8. Fulltext Stability study of an exothermic biocatalytic reaction and its application in bioprocess systems
    Mohd. Radzi, M.R., Uzir, M.H.
    Pertanika Journal of Science & Technology, 2009;17(1):-.
    MyJurnal
    Biocatalytic reaction is a type of reaction which uses enzyme or whole-cell as a (bio)-catalyst to achieve a desired conversion, under controlled conditions in a bioreactor. Temperature produces opposed effects on enzyme activity and stability, and is therefore a key variable in any biocatalytic processes. An exothermic biocatalytic reaction, in a continuous-stirred-tank reactor (CSTR), was analyzed where dynamic equations (non-linear differential equations) could be derived from the Michaelis-Menten and Arrhenius equations, by performing mass and energy balances on the reactor. In this work, the effects of the different parameters such as dilution rate, proportional control constant and dimensionless total enzyme concentration, on the stability of the system, were studied. The stability of the reaction could be analyzed, based on the ODE (ordinary differential equation), solved using the numerical technique in MATLAB® and the analytical investigation using Mathematica.® The numerical analysis can be carried out by considering the hase-plane behaviour and bifurcation diagrams of the dynamic equations, while the analytical analysis using Mathematica® can be undertaken by evaluating the eigenvalues of the system. In order to model the operational stability of biocatalysts, modulation factors need to be considered so that a proper design of bioreactors can be done. Temperature, as a key variable in such bioprocess systems, can be conveniently optimized through the use of appropriate models.
    Matched MeSH terms: Bioreactors
  9. Fulltext Production of ethanol by fed-batch fermentation
    Ngoh, Gek Cheng, Masitah Hasan, Kumoro, Andri Chahyo, Chew, Fui Ling, Tham, Margaret
    Pertanika Journal of Science & Technology, 2009;17(2):-.
    MyJurnal
    The production of ethanol, from glucose in batch and fed batch culture, was investigated. In the fed batch culture, the glucose feeding was added into the culture at 16th hour of fermentation. The effects of different glucose concentration feeding rates on ethanol fermentation were investigated for fed batch culture. The 2gL-1hr-1 glucose concentration feeding rate was found to give higher ethanol yield (2.47 g ethanol g glucose-1), with respect to substrate consumed as compared to 8 gL-1hr-1 (0.23 g ethanol g glucose-1) and 4 gL-1hr-1 (0.20 g ethanol g glucose-1). The ethanol yield with respect to substrate consumed obtained in batch culture was 0.81 g ethanol g glucose-1. The fed batch culture at 2 gL-1hr-1 glucose concentration feeding rate was proven to be a better fermentation system than the batch culture. The specific growth rate, specific glucose consumption rate and specific ethanol production rate for the fed batch fermentation, at 2 gL-1hr-1 glucose concentration feeding rate, were 0.065 hr-1, 1.20 hr-1 and 0.0009 hr-1, respectively.
    Matched MeSH terms: Bioreactors
  10. Fulltext Bifurcation/chaos and their practical relevance to chemical and biological systems
    Said S. E. H. Elnashaie
    Pertanika Journal of Science & Technology, 2014;22(2):337-364.
    MyJurnal
    Bifurcation and chaos are important phenomena affecting many physical and chemical systems. They are also related to the stability/instability and multiplicity phenomena associated with these systems. The phenomena are not only of theoretical/mathematical interest but are also important for laboratory, pilot plant and commercial units. This paper concentrates on 3 systems:

    1. The novel auto-thermic Circulating Fluidized Membrane Steam Reformer (CFBMSR) for the efficient production of the clean fuel hydrogen and which shows multiplicity of the steady state (static bifurcation)

    2. A novel fermentor for the efficient production of bio-ethanol that shows static/dynamic bifurcation as well as chaotic behaviour

    3. The neurocycle of the acetylcholine transmitter in the brain using diffusion-reaction models in order to gain insight into their possible connection to Alzheimer and Parkinson Diseases (AD/PD); these are preliminary efforts to investigate the bifurcation and chaotic behaviour of this neurocycle.
    Matched MeSH terms: Bioreactors
  11. Optimization of Culture Medium for the Growth of Candida sp. and Blastobotrys sp. as Starter Culture in Fermentation of Cocoa Beans (Theobroma cacao) Using Response Surface Methodology (RSM)
    Mahazar NH, Zakuan Z, Norhayati H, MeorHussin AS, Rukayadi Y
    Pak J Biol Sci, 2017;20(3):154-159.
    PMID: 29023007 DOI: 10.3923/pjbs.2017.154.159
    BACKGROUND AND OBJECTIVE: Inoculation of starter culture in cocoa bean fermentation produces consistent, predictable and high quality of fermented cocoa beans. It is important to produce healthy inoculum in cocoa bean fermentation for better fermented products. Inoculum could minimize the length of the lag phase in fermentation. The purpose of this study was to optimize the component of culture medium for the maximum cultivation of Candida sp. and Blastobotrys sp.

    MATERIALS AND METHODS: Molasses and yeast extract were chosen as medium composition and Response Surface Methodology (RSM) was then employed to optimize the molasses and yeast extract.

    RESULTS: Maximum growth of Candida sp. (7.63 log CFU mL-1) and Blastobotrys sp. (8.30 log CFU mL-1) were obtained from the fermentation. Optimum culture media for the growth of Candida sp., consist of 10% (w/v) molasses and 2% (w/v) yeast extract, while for Blastobotrys sp., were 1.94% (w/v) molasses and 2% (w/v) yeast extract.

    CONCLUSION: This study shows that culture medium consists of molasses and yeast extract were able to produce maximum growth of Candida sp. and Blastobotrys sp., as a starter culture for cocoa bean fermentation.

    Matched MeSH terms: Bioreactors/microbiology*
  12. Removal of headspace CO2 increases biological hydrogen production by C. acetobutylicum
    Alshiyab H, Kalil MS, Hamid AA, Yusoff WM
    Pak J Biol Sci, 2008 Oct 01;11(19):2336-40.
    PMID: 19137867
    The effect of removal of resultant gas resulted in enhancement of the H2 yield. The technique of CO2 scavenging resulted in H2 yield being improved from 408 mL g(-1) to reach the maximum of 422 mL g'. The highest hydrogen productivity of 87.9 ml L(-1) h(-1) was obtained by CO2 scavenging. Biomass concentration was enhanced to 1.47 g L(-1), Y(P,X) of 287 ml g(-1) L(-1), Y(X/S) of 0.294 and Y(H2/s) of 0.0377 by the use of CO2 scavenging. The results suggested that the presence of the gaseous products in fermentation medium and headspace adversely effect biomass growth and hydrogen production.
    Matched MeSH terms: Bioreactors
  13. Xylanase production by Aspergillus niger FTCC 5003 using palm kernel cake in fermentative bioprocess
    Abdeshahian P, Samat N, Yusoff WM
    Pak J Biol Sci, 2009 Aug 01;12(15):1049-55.
    PMID: 19943460
    The production of xylanase from palm kernel cake as a substrate was studied in solid substrate fermentation. The simultaneous effects of three independent variables, namely incubation temperature, initial moisture content of substrate and air flow rate on xylanase production were evaluated by response surface methodology using central composite face centered design. A total of 18 experiments were carried out in which Aspergillus niger FTCC 5003 was cultivated on palm kernel cake in a column bioreactor for 7 days under incubation temperature, moisture level and aeration rate determined. Test results showed that the highest xylanase activity of 174.88 U g(-1) was produced at incubation temperature, initial moisture level and aeration rate of 25 degrees C, 60% and 1.5 L min(-1), respectively. The statistical analysis of the experimental results revealed that the linear effect of incubation temperature and quadratic term of initial moisture content had highly significant effects on xylanase production (p<0.01). Statistical results also showed that interaction effect between incubation temperature and initial moisture content as well as interaction effect between moisture level and aeration rate influenced the yield ofxylanase at probability levels of 95%. Optimum conditions determined by statistical model for attaining maximum xylanase production were incubation temperature of 25 degrees C, initial moisture level of 63% and aeration rate of 1.76 L min(-1). The xylanase activity of 192.50 U g(-1) was obtained when solid substrate fermentation was performed under the optimal circumstances.
    Matched MeSH terms: Bioreactors
  14. Large-scale culture of a tropical marine microalga Chaetoceros calcitrans (Paulsen) Takano 1968 at different temperatures using annular photobioreactors
    Lai JI, Yusoff FM, Shariff M
    Pak J Biol Sci, 2012 Jul 01;15(13):635-40.
    PMID: 24218933
    Outdoor mass culture of microalgae in the tropical area is important to minimize its production cost. This study evaluates the growth of Chaetoceros calcitrans in 120 L annular photobioreactors at indoor temperature (Treatment I, 25 +/- 2 degrees C) and outdoor tropical ambient temperature, (Treatment II, 30 +/- 6 degrees C). Each treatment was done in duplicates. For both treatments, C. calcitrans was first grown in starter columns of 10 L capacity for a period of 7 days at 25 +/- 2 degrees C. After 7 days, the 9 L culture was transferred to the annular photobioreactors and subsequently brought to a final volume of 100 L by adding 20 L fresh medium every 5 days. There was no significant difference (p > 0.05) in the dry weight of microalgae grown in natural light and those grown indoor. The results suggest that C. calcitrans can be grown in outdoor conditions, hence, saving time and microalgae production cost for the larviculture industry.
    Matched MeSH terms: Bioreactors*
  15. Applications of the Box-Wilson design model for bio-hydrogen production using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564)
    Alalayah WM, Kalil MS, Kadhum AA, Jahim J, Zaharim A, Alauj NM, et al.
    Pak J Biol Sci, 2010 Jul 15;13(14):674-82.
    PMID: 21848059
    Box-Wilson design (BWD) model was applied to determine the optimum values of influencing parameters in anaerobic fermentation to produce hydrogen using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564). The main focus of the study was to find the optimal relationship between the hydrogen yield and three variables including initial substrate concentration, initial medium pH and reaction temperature. Microbial growth kinetic parameters for hydrogen production under anaerobic conditions were determined using the Monod model with incorporation of a substrate inhibition term. The values of micro(max) (maximum specific growth rate) and K, (saturation constant) were 0.398 h(-1) and 5.509 g L(-1), respectively, using glucose as the substrate. The experimental substrate and biomass-concentration profiles were in good agreement with those obtained by the kinetic-model predictions. By varying the conditions of the initial substrate concentration (1-40 g L(-1)), reaction temperature (25-40 degrees C) and initial medium pH (4-8), the model predicted a maximum hydrogen yield of 3.24 mol H2 (mol glucose)(-1). The experimental data collected utilising this design was successfully fitted to a second-order polynomial model. An optimum operating condition of 10 g L(-1) initial substrate concentration, 37 degrees C reaction temperature and 6.0 +/- 0.2 initial medium pH gave 80% of the predicted maximum yield of hydrogen where as the experimental yield obtained in this study was 77.75% exhibiting a close accuracy between estimated and experimental values. This is the first report to predict bio-hydrogen yield by applying Box-Wilson Design in anaerobic fermentation while optimizing the effects of environmental factors prevailing there by investigating the effects of environmental factors.
    Matched MeSH terms: Bioreactors*
  16. Studies on extraction of mannanase enzyme by Aspergillus terreus SUK-1 from fermented palm kernel cake
    Rashid JI, Samat N, Yusoff WM
    Pak J Biol Sci, 2013 Sep 15;16(18):933-8.
    PMID: 24502150
    Microbial mannanases have become biotechnologically important in industry but their application is limited due to high production cost. In presents study, the extraction of mannanase from fermented Palm Kernel Cake (PKC) in the Solid State Fermentation (SSF) was optimized. Local isolate of Aspergillus terreus SUK-1 was grown on PKC in (SSF) using column bioreactor. The optimum condition were achieved after two washes of fermented PKC by adding of 10% glycerol (v/v) soaked for 10 h at the room temperature with solvent to ratio, 1:5 (w/v).
    Matched MeSH terms: Bioreactors
  17. Fulltext Integrated Stirred-Tank Bioreactor with Internal Adsorption for the Removal of Ammonium to Enhance the Cultivation Performance of gdhA Derivative Pasteurella multocida B:2
    Oslan SNH, Tan JS, Abbasiliasi S, Ziad Sulaiman A, Saad MZ, Halim M, et al.
    Microorganisms, 2020 Oct 24;8(11).
    PMID: 33114463 DOI: 10.3390/microorganisms8111654
    Growth of mutant gdhA Pasteurella multocida B:2 was inhibited by the accumulation of a by-product, namely ammonium in the culture medium during fermentation. The removal of this by-product during the cultivation of mutant gdhA P. multocida B:2 in a 2 L stirred-tank bioreactor integrated with an internal column using cation-exchange adsorption resin for the improvement of cell viability was studied. Different types of bioreactor system (dispersed and internal) with resins were successfully used for ammonium removal at different agitation speeds. The cultivation in a bioreactor integrated with an internal column demonstrated a significant improvement in growth performance of mutant gdhA P. multocida B:2 (1.05 × 1011 cfu/mL), which was 1.6-fold and 8.4-fold as compared to cultivation with dispersed resin (7.2 × 1010 cfu/mL) and cultivation without resin (1.25 × 1010 cfu/mL), respectively. The accumulation of ammonium in culture medium without resin (801 mg/L) was 1.24-fold and 1.37-fold higher than culture with dispersed resin (642.50 mg/L) and culture in the bioreactor integrated with internal adsorption (586.50 mg/L), respectively. Results from this study demonstrated that cultivation in a bioreactor integrated with the internal adsorption column in order to remove ammonium could reduce the inhibitory effect of this by-product and improve the growth performance of mutant gdhA P. multocida B:2.
    Matched MeSH terms: Bioreactors
  18. Fulltext Evaluation of the Estimation Capability of Response Surface Methodology and Artificial Neural Network for the Optimization of Bacteriocin-Like Inhibitory Substances Production by Lactococcus lactis Gh1
    Jawan R, Abbasiliasi S, Tan JS, Kapri MR, Mustafa S, Halim M, et al.
    Microorganisms, 2021 Mar 12;9(3).
    PMID: 33809201 DOI: 10.3390/microorganisms9030579
    Bacteriocin-like inhibitory substances (BLIS) produced by Lactococcus lactis Gh1 had shown antimicrobial activity against Listeria monocytogenes ATCC 15313. Brain Heart Infusion (BHI) broth is used for the cultivation and enumeration of lactic acid bacteria, but there is a need to improve the current medium composition for enhancement of BLIS production, and one of the approaches is to model the optimization process and identify the most appropriate medium formulation. Response surface methodology (RSM) and artificial neural network (ANN) models were employed in this study. In medium optimization, ANN (R2 = 0.98) methodology provided better estimation point and data fitting as compared to RSM (R2 = 0.79). In ANN, the optimal medium consisted of 35.38 g/L soytone, 16 g/L fructose, 3.25 g/L sodium chloride (NaCl) and 5.40 g/L disodium phosphate (Na2HPO4). BLIS production in optimal medium (717.13 ± 0.76 AU/mL) was about 1.40-fold higher than that obtained in nonoptimised (520.56 ± 3.37 AU/mL) medium. BLIS production was further improved by about 1.18 times higher in 2 L stirred tank bioreactor (787.40 ± 1.30 AU/mL) as compared to that obtained in 250 mL shake flask (665.28 ± 14.22 AU/mL) using the optimised medium.
    Matched MeSH terms: Bioreactors
  19. Fulltext Mesophilic versus thermophilic anaerobic digestion of cattle manure: methane productivity and microbial ecology
    Moset V, Poulsen M, Wahid R, Højberg O, Møller HB
    Microb Biotechnol, 2015 Sep;8(5):787-800.
    PMID: 25737010 DOI: 10.1111/1751-7915.12271
    In this study, productivity and physicochemical and microbiological (454 sequencing) parameters, as well as environmental criteria, were investigated in anaerobic reactors to contribute to the ongoing debate about the optimal temperature range for treating animal manure, and expand the general knowledge on the relation between microbiological and physicochemical process indicators. For this purpose, two reactor sizes were used (10 m(3) and 16 l), in which two temperature conditions (35°C and 50°C) were tested. In addition, the effect of the hydraulic retention time was evaluated (16 versus 20 days). Thermophilic anaerobic digestion showed higher organic matter degradation (especially fiber), higher pH and higher methane (CH₄) yield, as well as better percentage of ultimate CH₄ yield retrieved and lower residual CH₄ emission, when compared with mesophilic conditions. In addition, lower microbial diversity was found in the thermophilic reactors, especially for Bacteria, where a clear intensification towards Clostridia class members was evident. Independent of temperature, some similarities were found in digestates when comparing with animal manure, including low volatile fatty acids concentrations and a high fraction of Euryarchaeota in the total microbial community, in which members of Methanosarcinales dominated for both temperature conditions; these indicators could be considered a sign of process stability.
    Matched MeSH terms: Bioreactors/microbiology*
  20. Fulltext Dynamics of Microbial Populations Responsible for Biodegradation during the Full-Scale Treatment of Palm Oil Mill Effluent
    Mohd-Nor D, Ramli N, Sharuddin SS, Hassan MA, Mustapha NA, Ariffin H, et al.
    Microbes Environ, 2019 Jun 27;34(2):121-128.
    PMID: 30905894 DOI: 10.1264/jsme2.ME18104
    Despite efforts to address the composition of the microbial community during the anaerobic treatment of palm oil mill effluent (POME), its composition in relation to biodegradation in the full-scale treatment system has not yet been extensively examined. Therefore, a thorough analysis of bacterial and archaeal communities was performed in the present study using MiSeq sequencing at the different stages of the POME treatment, which comprised anaerobic as well as facultative anaerobic and aerobic processes, including the mixed raw effluent (MRE), mixing pond, holding tank, and final discharge phases. Based on the results obtained, the following biodegradation processes were suggested to occur at the different treatment stages: (1) Lactobacillaceae (35.9%) dominated the first stage, which contributed to high lactic acid production; (2) the higher population of Clostridiaceae in the mixing pond (47.7%) and Prevotellaceae in the holding tank (49.7%) promoted acetic acid production; (3) the aceticlastic methanogen Methanosaetaceae (0.6-0.8%) played a role in acetic acid degradation in the open digester and closed reactor for methane generation; (4) Syntrophomonas (21.5-29.2%) appeared to be involved in the degradation of fatty acids and acetic acid by syntrophic cooperation with the hydrogenotrophic methanogen, Methanobacteriaceae (0.6-1.3%); and (5) the phenols and alcohols detected in the early phases, but not in the final discharge phase, indicated the successful degradation of lignocellulosic materials. The present results contribute to a better understanding of the biodegradation mechanisms involved in the different stages of the full-scale treatment of POME.
    Matched MeSH terms: Bioreactors/microbiology
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