Effect Of Medium Composition Research Articles

BESSICC, a COSMO‐RS based tool for in silico solvent screening of biocatalyzed reactions

Many enzymatic reactions are near-equilibrium reactions. This often limits final yield and hence application of biocatalyzed processes in the industrial production. The most widely applied strategy to overcome this issue is solvent selection. It must be underlined that measuring the equilibrium position experimentally is a difficult and time-consuming procedure and any tool for predicting the solvent effect on the reaction equilibrium can be very valuable. The present work reports on the development of BESSICC, an algorithm to calculate the effect of medium composition on biocatalyzed reactions equilibrium. It is based on COSMO-RS calculation of activity coefficients of all the species in the reaction mixture and minimization of Gibbs free energy of the reaction. Starting from one single experimental measurement of the equilibrium position for a given biocatalyzed reaction it can predict the yield of the reaction in any other solvent or solvent mixture. Predictions are accurate, the errors of prediction are in average below 25% for the esterification of dodecanoic acid with menthol and below 65% for esterification of 1-dodecanoic acid with 1-dodecanol. The best predictions show an error well below 5%.

Optimization of Submerged Culture Conditions for Mycelial Growth and Extracellular Polysaccharide Production by Coriolus versiolor

This paper is concerned with optimization of submerged culture conditions for mycelial growth and Exopolysaccharides (EPS) yield with Coriolus versiolor by both one-factor-at-a-time and orthogonal matrix methods. Glucose and yeast-Extracts were identified to be the most suitable carbon and nitrogen sources, respectively. The optimal initial pH, inoculum size and liquid volume for mycelial growth and EPS yield were 5.0, 8% and 150mL/500mL, respectively. Subsequently, the concentration of glucose, yeast-extract, KH2PO4, and MgSO4•7H2O were optimized using the orthogonal matrix method. The effects of media composition on the mycelial growth of Coriolus versiolor were in the order of glucose >KH2PO4 > yeast-extract > MgSO4•7H2O, and those on EPS yield were in the order of glucose >MgSO4•7H2O> yeast-extract >KH2PO4.The optimal concentrations for enhanced yield were determined as 30 g/L glucose, 7.0 g/L yeast-extract, 1.0 g/L KH2PO4, 1.0 g/L MgSO4•7H2O, and 40 g/L glucose, 6.0 g/L yeast-extract, 1.0 g/L KH2PO4, 1.5 g/L MgSO4•7H2O for mycelial and EPS yield, respectively. The verification experiments confirmed the final medium. This optimization strategy (30 g/L glucose, 7.0 g/L yeast-extract, 2.0 g/L KH2PO4 and 0.5 g/L MgSO4•7H2O) in shake flask culture lead to a mycelial yield of 5.18 g/L, and EPS yield of 0.64 g/L, respectively, which were considerably higher than those obtained in preliminary studies. Under optimal culture conditions, the maximum EPS concentration in a 5-L stirred-tank bioreactor was 0.75 g/L, while the maximum mycelial yield was 8.55 g/L. This also corresponded to 14.67% and 39.42% enhancement in EPS yield and mycelial dry weight, respectively, compared with the verification test results.

Effects of medium composition and the sealing material used for Petri dishes on the growth of callus of Melia azedarach L.

SummaryLittle information is available on the growth of Melia azedarach L. callus during repeated sub-cultures. The present research aimed to improve our knowledge on the influence of auxins and the sealing material used for Petri dishes on the composition of the gaseous micro-environment and on the growth of callus, in order to achieve long-lasting proliferation of homogeneous callus. Continuous callus growth [to approx. six-times the initial fresh weight (FW) after 4 weeks in culture] was obtained using 4.4 µM 6-benzyladenine (BA) and 4 mg l–1 (19.7 µM) indole-3-butyric acid (IBA) in 90-mm Petri dishes sealed with polyvinyl chloride (PVC) strips. Reduced callus FW and browning were observed in Petri dishes sealed with Parafilm M® (PARA), especially for callus grown on α-naphthaleneacetic acid (NAA)-enriched media. Data on callus growth rates in bottles were mostly in agreement with data from Petri dishes, although FWs were 25 – 35% lower, except for the NAA-PVC-dish closure combination. Moreover, high concentrations of ethylene and carbon dioxide (up to approx. 12 µmol mol–1 and 200 mmol mol–1, respectively) and low rates of callus growth were found in PARA-sealed bottles.

Determination of mercury in ethanol biofuel by photochemical vapor generation

A new procedure based on exposure of ethanol biofuel samples to UV radiation in the presence of low molecular weight organic acids was developed for the determination of total Hg (inorganic and organometallic species: Hg2+, CH3Hg+ and CH3CH2Hg+) by photochemical vapor generation coupled with atomic absorption spectrometry (photo-CV-AAS). For each species, the optimum conditions for photochemical generation were investigated, including the effects of medium composition, exposure time to the UV radiation and transfer gas flow rate. The accuracy was evaluated by assessing the recoveries of species-specific spikes (91–107%) as well as by assessing recovery from a mixture of all species of the mercury added to the ethanol biofuel samples based on calibration standards prepared in high purity bidistilled ethanol. The limits of detection ranged from 0.05 to 0.09 μg L−1 for all addition and recovery tests, enabling the determination of total Hg. The proposed method is sensitive, simple (no sample pretreatment) and provides a direct approach to the generation of mercury vapor from ethanol biofuel samples while promoting “green” chemistry.

Low-cost production of 6G-fructofuranosidase with high value-added astaxanthin by Xanthophyllomyces dendrorhous

The effects of medium composition and culture conditions on the production of 6G-fructofuranosidase with value-added astaxanthin were investigated to reduce the capital cost of neo-fructooligosaccharides (neo-FOS) production by Xanthophyllomyces dendrorhous. The sucrose and corn steep liquor (CSL) were found to be the optimal carbon source and nitrogen source, respectively. CSL and initial pH were selected as the critical factors using Plackett–Burman design. Maximum 6G-fructofuranosidase 242.57U/mL with 5.23mg/L value-added astaxanthin was obtained at CSL 52.5mL/L and pH 7.89 by central composite design. Neo-FOS yield could reach 238.12g/L under the optimized medium conditions. Cost analysis suggested 66.3% of substrate cost was reduced compared with that before optimization. These results demonstrated that the optimized medium and culture conditions could significantly enhance the production of 6G-fructofuranosidase with value-added astaxanthin and remarkably decrease the substrate cost, which opened up possibilities to produce neo-FOS industrially.

Bacteriocins from Qatari Bacillus Thuringiensis Crystal Producing Strains

Abstract Antimicrobial agents are very useful and have been the subject of intense research. Amongst these compounds, bacteriocins are defined as peptide antibiotics which do not harm the producer strain but have the ability to kill closely related bacteria. Bacillus thuringiensis is a friendly bacterium best known for the production of bioinsecticides, but is also considered as a source of bacteriocins active against the closely related pathogenic species harmful for food products, and many organisms. The major goal of this project is to evidence and characterize novel Bacillus thuringiensis bacteriocins synthesized by Qatari Bacillus thuringiensis strains. In order to obtain that, many approaches have been adopted: - Screening of delta-endotoxin producing strains of Bacillus thuringiensis. - Screening of bacteriocin producing strains of Bacillus thuringiensis. - Study of the antagonistic effects among bacteriocin producing strains. - Study of the effect of medium composition on bacteriocin synthesis. - Screening by PCR of Bacthuricin F4 like producing strains. In order to screen the bacteriocin producing strains of Bacillus thuringiensis, many techniques have been utilized such as: Direct Antagonism on Solid Media and Well Diffusion Method to check the bacteriocin activity. Bacteriocin production was studied on different growth media and against various indicator strains. The screening of 192 Bacillus thuringiensis strains isolated from Qatar, allowed the evidence of strains having different crystal forms. In fact, these strains produce parasporal crystals that have pyramidal, bipyramidal, cubical, spherical and amorphous forms. Among these Bacillus thuringiensis strains, about 70% produce spherical crystals and 30 % bipyramidal. Similar results were obtained in the laboratory by Sara Zakzok and Duha Rabah. This could be considered as a contribution to the establishment of Qatari bacterial gene bank. Screening the collection for bactericidal activities against indicator strains, revealed a variability in the size and aspect of the inhibition zones. About 76% of the collection were bacteriocin producing strains and only 24% were negative. There have been noticed many signs of novelty among our local bacteriocin producing strains. These results are very encouraging and in favour of the use of B. thuringiensis local strains for bacteriocin production.

Heterologous expression, biochemical characterization, and overproduction of alkaline α-amylase from Bacillus alcalophilus in Bacillus subtilis

BackgroundAlkaline α-amylases have potential applications for hydrolyzing starch under high pH conditions in the starch and textile industries and as ingredients in detergents for automatic dishwashers and laundries. While the alkaline α-amylase gains increased industrial interest, the yield of alkaline α-amylases from wild-type microbes is low, and the combination of genetic engineering and process optimization is necessary to achieve the overproduction of alkaline α-amylase.ResultsThe alkaline α-amylase gene from Bacillus alcalophilus JN21 (CCTCC NO. M 2011229) was cloned and expressed in Bacillus subtilis strain WB600 with vector pMA5. The recombinant alkaline α-amylase was stable at pH from 7.0 to 11.0 and temperature below 40°C. The optimum pH and temperature of alkaline α-amylase was 9.0 and 50°C, respectively. Using soluble starch as the substrate, the Km and Vmax of alkaline α-amylase were 9.64 g/L and 0.80 g/(L·min), respectively. The effects of medium compositions (starch, peptone, and soybean meal) and temperature on the recombinant production of alkaline α-amylase in B. subtilis were investigated. Under the optimal conditions (starch concentration 0.6% (w/v), peptone concentration 1.45% (w/v), soybean meal concentration 1.3% (w/v), and temperature 37°C), the highest yield of alkaline α-amylase reached 415 U/mL. The yield of alkaline α-amylase in a 3-L fermentor reached 441 U/mL, which was 79 times that of native alkaline α-amylase from B. alcalophilus JN21.ConclusionsThis is the first report concerning the heterologous expression of alkaline α-amylase in B. subtilis, and the obtained results make it feasible to achieve the industrial production of alkaline α-amylase with the recombinant B. subtilis.

Optimal culture conditions for keratinase production by a novel thermophilicMyceliophthora thermophilastrain GZUIFR-H49-1

To investigate the effect of medium compositions and culture conditions on keratinase production by a novel thermophilic fungus Myceliophthora thermophila (Apinis) Oorschot strain GZUIFR-H49-1. The thermophilic strain GZUIFR-H49-1 with keratinolytic ability was characterized and identified as a strain of M. thermophila on the basis of its morphological characters and molecular analysis of ITS1-5.8S-ITS2 rDNA sequence. Among the medium compositions tested, the soluble starch (SS), urea, sodium thiosulfate and CaCl2 were the most effective C-source, N-source, S-source and mineral ion, respectively, by employing the single-factor experiment. The urea and pH value were the significant factors (P < 0·05) for the keratinase production in this experiment condition using Plackett–Burman factorial design. The conditions of keratinase production were further optimized by Box–Behnken design. Consequently, there was a 6·4-fold increase (5100 U l−1) in the keratinase activity than the initial value (800 U l−1) by this optimal process. This study indicated that the optimization design proved a useful and powerful tool for the development of optimal medium compositions and culture conditions. Myceliophthora thermophila strain GZUIFR-H49-1 was a promising fungus strain for keratinase production.

Effect of Medium Composition and Culture Condition on the Production of Bacteriocin-Like Inhibitory Substances (BLIS) by Lactobacillus Paracasei LA07, a Strain Isolated from Budu

ABSTRACTThe effect of medium composition (type and concentration of carbon and nitrogen sources) and culture conditions (pH, aeration and temperature) on the production of bacteriocin-like inhibitory substances (BLIS) by Lactobacillus paracasei LA07 was studied in shake flask culture. The highest BLIS production was obtained from de Man, Rogosa and Sharpe (MRS) broth, which was 4%, 22%, 51% and 63% higher than those obtained in M17 Broth, Tryptic Soy Broth (TSB), Brain Heart Infusion Broth (BHIB) and Nutrient Broth (NB) respectively. The addition of meat extract (5 g/L) and yeast extract (5 g/L) to MRS broth increased further BLIS production by 5% and 8%, respectively. The production of BLIS was further improved by 11% and 13% through the addition of tryptone (3 g/L) and glucose (10 g/L), respectively. The growth of Lb. paracasei LA07 and BLIS production were not significantly affected by agitation, either in anaerobic or in aerobic conditions. The optimum initial pH and temperature for BLIS production by Lb. paracasei LA07 was pH 8.5 and 30 °C, respectively.

Isolation, Optimisation and Purification of Lipase Production by Pseudomonas Aeruginosa

Six isolates of lipase producing (Ps1, Ps2, Ps3, Ps4, Ps5 and Ps6) were secreened from wastewater on a selective medium agar that contained tween 80 or olive oil as the only source of carbon. The isolate showed highest lipase activity was Ps5 which later was identified as Pseudomonas aeruginosa. The effect of media composition was analysed to maximize production of lipase. The maximum extracellular lipase present in the broth was purified 11 folds with an overall yield of 65.51 % through purification procedure of ammonium sulphate precipitation and DEAE cellulose chromatography. The purified lipase had maximal activity within the pH range of 6-8, with an optimum PH of 7, and within the temperature range of 25 – 35°C, with optimum temperature for the hydrolysis of olive oil at 35°C. The lipase activity of the enzyme was enchanced by Ca+2 and Mg+2 but strongly inhibited by heavy metals Zn+2, Cu+2and Mn+2.

Effect of Medium Composition on the Synthesis of Chitinase and Chitin Deacetylase from Thermophilic Paenibacillus sp.Hul

To investigate the effects of nutritional components and initial pH on chitinase and chitin deacetylase production by thermophilic Paenibacillus sp. Hul, and provide basis for fermentation of enzymes and preparation of chito- oligosaccharides. The shake flask culture was employed to research the culture conditions of thermophilic Paenibacillus sp. Hu1 for producing chitinase and chitin deacetylase. The results show that the optimal carbon source was chitin powder with 35g/L; while yeast extract power was the optimal nitrogen source with 10g/L. It was beneficial to synthesize chitinase and chitin deacetylase when the initial pH was 6.0. In addition, the synthesis of chitinase and chitin deacetylase was inhibited by Cu2+, and activated by Ca2+. However, Mg2+ and Zn2+ did not show significant inhibitory or activation effects on the synthesis of the two enzymes. The hydrolysate components were analyzed using chitin as substrate with the crude enzyme, and the result suggested that enzymatic hydrolysates were mainly centralized in chito-oligosaccharides with polymerization number less than hexaose.

Enhanced Production of Medicinal Polysaccharide by Submerged Fermentation of Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidium (W.Curt.:Fr.) P. Karst. Using Statistical and Evolutionary Optimization Methods

Statistical and evolutionary optimization of media composition was employed for the production of medicinal exopolysaccharide (EPS) by Lingzhi or Reishi medicinal mushroom Ganoderma lucidium MTCC 1039 using soya bean meal flour as low-cost substrate. Soya bean meal flour, ammonium chloride, glucose, and pH were identified as the most important variables for EPS yield using the two-level Plackett-Burman design and further optimized using the central composite design (CCD) and the artificial neural network (ANN)-linked genetic algorithm (GA). The high value of coefficient of determination of ANN (R² = 0.982) indicates that the ANN model was more accurate than the second-order polynomial model of CCD (R² = 0.91) for representing the effect of media composition on EPS yield. The predicted optimum media composition using ANN-linked GA was soybean meal flour 2.98%, glucose 3.26%, ammonium chloride 0.25%, and initial pH 7.5 for the maximum predicted EPS yield of 1005.55 mg/L. The experimental EPS yield obtained using the predicted optimum media composition was 1012.36 mg/L, which validates the high degree of accuracy of evolutionary optimization for enhanced production of EPS by submerged fermentation of G. lucidium.

Effect of medium composition on the proliferation, morphology and exopolysaccharides production of Aureobasidium pullulans

Effect of medium composition on the proliferation, morphology and exopolysaccharides production of Aureobasidium pullulans

Determination of the Effects of Medium Composition on the Monochloramine Disinfection Kinetics of Nitrosomonas europaea by the Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods

Various medium compositions (phosphate, 1 to 50 mM; ionic strength, 2.8 to 150 meq/liter) significantly affected Nitrosomonas europaea monochloramine disinfection kinetics, as determined by the Live/Dead BacLight (LD) and propidium monoazide quantitative PCR (PMA-qPCR) methods (lag coefficient, 37 to 490 [LD] and 91 to 490 [PMA-qPCR] mg·min/liter; Chick-Watson rate constant, 4.0 × 10(-3) to 9.3 × 10(-3) [LD] and 1.6 × 10(-3) to 9.6 × 10(-3) [PMA-qPCR] liter/mg·min). Two competing effects may account for the variation in disinfection kinetic parameters: (i) increasing kinetics (disinfection rate constant [k] increased, lag coefficient [b] decreased) with increasing phosphate concentration and (ii) decreasing kinetics (k decreased, b increased) with increasing ionic strength. The results support development of a standard medium for evaluating disinfection kinetics in drinking water.

EFFECT OF MEDIUM COMPOSITION ON ASYMBIOTIC SEED GERMINATION OF FIVE PHALAENOPSIS SPECIES

Phalaenopsis has become one of the most important flowering potted plants in the world. In order to create novel flower colors and types, various species have been introduced in breeding programs. For the conservation and sustainable utilization of the germplasm, here, we investigated the effect of medium composition on the asymbiotic germination and seedling development of five Phalaenopsis species. Seeds germinated well on 1/10, 1/4 and 1/2 MS media; however, the survival percentage of young protocorms differed depending on the species and the concentrations of MS media. The optimum strength for protocorm survival of P. aphrodite subsp. formosana and P. philippinensis was 1/10 MS salts. For P. appendiculata, the protocorm survival was significantly higher in 1/2 MS medium than the others. For P. lindenii and P. viridis, the optimum strength was found in 1/4 and 1/10 MS media. For the organic supplements tested, the higher survival percentage and better growth of protocorms were found on the supplements of either potato homogenate or coconut water. From the results of this study, the requirements of inorganic salt and organic supplements for seed germination and protocorm development in vitro are dissimilar with the modern hybrids. The various responses to the basal salt concentrations among these species may be related to the diversity of their natural habitats.

Effect of medium composition and light on root and rhinacanthin formation in Rhinacanthus nasutus cultures

Rhinacanthus nasutus (L.) Kurz (Acanthaceae) has long been used in Thai traditional medicine for treatment of tinea versicolor, ringworm, pruritic rash, and abscess. The active constituents are known as a group of naphthoquinone esters, rhinacanthins. This work focused on establishment of R. nasutus root cultures and determination of rhinacanthin production. Induction of R. nasutus root formation was accomplished on solid Gamborg’s B5 (B5) medium, supplied with 0.1 mg/L indole-3-butyric acid (IBA) and 20 g/L sucrose. The effects of explants (whole leaf explants and four-side excised leaf explants), light and medium composition on root and rhinacanthin formation were investigated. The root formation from the whole leaf explants was 10 times higher than that from the four-side excised leaf explants. In addition, light possessed an inhibitory effect on the root and rhinacanthin formation of R. nasutus. Medium manipulation found that Murashige and Skoog (MS) medium supplied with 3 mg/L IBA and 30 g/L sucrose was the most suitable for induction of the root formation. Unfortunately, the obtained root cultures produced only rhinacanthin-C in very low amount, 0.026 mg/g dry weight (DW), when they were transferred into the same MS liquid medium. With semisolid medium (4 g/L agar) of the same MS composition, however, the root cultures appeared to produce higher content of rhinacanthin-C, -D and -N (3.45, 0.07 and 0.07 mg/g DW, respectively). Our finding suggests that culturing in semisolid medium is capable of improving of rhinacanthin production in R. nasutus root cultures.

Medium composition effects on solute partitioning in solid–liquid two‐phase bioreactors

AbstractBiphasic systems such as two‐phase partitioning bioreactors (TPPBs) have been used to alleviate biological inhibition by sequestering inhibitory compounds within an immiscible phase. The use of solid polymer beads as this auxiliary phase provides a fully biocompatible alternative to potentially toxic organic solvents. While guidelines exist for the rational selection of the polymer phase, the effect of the aqueous phase composition on molecular sequestration has not been explored in the literature. This work aims to identify aspects of medium composition that influence the partitioning of target molecules into the sequestering phase. Using benzaldehyde as the target molecule and Hytrel G3548L (DuPont) as the polymer phase, pH, temperature, salt and glucose concentrations, as well as ethanol concentrations, were examined for their effects on the partition coefficient. pH and temperature were observed to have no significant effect on benzaldehyde partitioning. Salt and glucose additions increased the partition coefficient by 173% and 30%, respectively, compared with pure reverse osmosis (RO) water, while increasing ethanol concentration was found to decrease the partition coefficient from 44 ( ± 1.6) to 1 ( ± 0.3). Strategic changes to the aqueous phase can be made to improve affinity of the sequestering phase for target molecules. This provides a simple and cost‐effective method to potentially improve TPPB system performance. Copyright © 2010 Society of Chemical Industry

Influence of medium composition on oxygen transfer rate in animal cell culture

AbstractExperiments were conducted in a 0.25 m diameter bubble column to investigate the effect of medium composition on oxygen transfer rate. Aqueous solutions, the composition of which mimics a mammalian cell culture medium, are used. The effect on oxygen transfer rate of additives used to protect cells against local hydrodynamic stresses induced by bubble coalescence and bursting is addressed, in the range of operating conditions (aeration rates) met in animal cell cultures.The mass transfer coefficient, the liquid viscosity and surface tension, and the bubble size distribution are measured as a function of liquid composition and of gas superficial velocity, allowing to decouple the effects of the different additive on kL and on a.

Reaction engineering studies for the production of 2-hydroxyisobutyric acid with recombinant Cupriavidus necator H 16

Recombinant Cupriavidus necator H 16 with a novel metabolic pathway using a cobalamin-dependent mutase was exploited to produce 2-hydroxyisobutyric acid (2-HIBA) from renewable resources through microbial fermentation. 2-HIBA production capacities of different strains of C. necator H 16 deficient in the PHB synthase gene and genetically engineered to enable the production of 2-HIBA from the intracellular PHB precursor (R)-3-hydroxybutyryl-CoA were evaluated in 48 parallel milliliter-scale stirred tank bioreactors (V = 11 mL). The effects of media composition, limitations, pH, and feed rate were studied with respect to the overall process performances of the different recombinant strains. 2-HIBA production was at a maximum at nitrogen limiting conditions and if the pH was controlled between 6.8 and 7.2 under fed-batch operating conditions (intermittent fructose addition). The final concentration of 2-HIBA was 7.4 g L(-1) on a milliliter scale. Best reaction conditions identified on the milliliter scale were transferred to a laboratory-scale fed-batch process in a stirred tank bioreactor (V = 2 L). Two different process modes for the production of 2-HIBA, a single-phase and a dual-phase fermentation procedure, were evaluated and compared on a liter scale. The final concentration of 2-HIBA was 6.4 g L(-1) on a liter scale after 2 days of cultivation.

In vitro propagation of a grape rootstock, deGrasset ( Vitis champinii Planch.): Effects of medium compositions and plant growth regulators

The aim of the present study was to develop a protocol for in vitro propagation of a grape rootstock, deGrasset, characterized by high tolerance to drought and salinity. Four medium compositions, MS, MS with 1/2 nitrates (MS-1), B5 and WPM, were tested for shoot growth from nodal explants and MS-1 medium produced significantly higher rate of shoot proliferation. MS-1 medium supplemented with 2.0 mg/L BAP was found to be optimum for culture establishment. The first subculturing on the same medium resulted in the production of 4–6, mostly short, hyperhydrated shoots per explant. For subsequent subcultures, a reduced concentration of BAP (1.0 mg/L) was used to prevent hyperhydricity, and that resulted in distinct individual shoot elongation. Three plant growth regulators, BAP, ZEA and TDZ, were tested for further shoot proliferation and BAP at 1.0 mg/L added to MS-1 medium displayed the highest proliferation rate (4.75 new explants per explant inoculated, in 6 weeks). For in vitro rooting of shoots, IAA at 0.2 mg/L was found to be optimum to produce highest response (84%) and an average number of 2.03 roots per shoot whereas use of IBA or NAA resulted in rooting with high frequency of callus formation. The acclimatized plantlets were established in soil under net house conditions with 87% success.