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Medium Composition (medium + composition)
Selected AbstractsOptimization of Medium Composition for Nisin Fermentation with Response Surface MethodologyJOURNAL OF FOOD SCIENCE, Issue 6 2008X.-X. Zhou ABSTRACT:, Nisin is an effective food biopreservative widely used in food industry. However, 1 problem of concern is limited production rate and final nisin concentration. A nisin-producing strain, L. lactis Lac2, a mutant strain with high yield of nisin, was obtained in our laboratory recently. In the present study, a fractional factorial design was applied to investigate the main factors that affect the yield of L. lactis Lac2. Central composite experimental design and response surface methodology were adopted to derive a statistical model for optimizing the composition of the medium. The results showed that the optimum medium for nisin production of L. lactis Lac2 was composed of 2.68% sucrose (w/v), 0.5% tryptone (w/v), 1% yeast extract (w/v), 0.3% Tween-80 (w/v), 0.02% MgSO4·7H2O (w/v), 0.81% NaCl (w/v), 1.91% K2HPO4 (w/v), 0.05% ascorbic acid (w/v), and 2% agar (w/v) (if necessary) at pH 6.5. When cultured in the optimum medium, the nisin yield is an average of 3381.81 IU/mL, which nearly doubled the yield when incubated in the initial medium. Also, the concentration of tryptone was decreased while that of the sucrose was increased when compared with CM broth, which means a reduction of the fermentation cost. [source] Combined Effects of Temperature and Medium Composition on Exopolysaccharide Production by Lactobacillusrhamnosus RW-9595M in a Whey Permeate Based MediumBIOTECHNOLOGY PROGRESS, Issue 2 2002Maria G. Macedo The effects of temperature (22,42 °C), whey permeate concentration (WP, 1.6,8.4%), and supplementation level with yeast nitrogen base (YNB, 0,2.0%) on exopolysaccharide (EPS) production was studied during 20 pH-controlled (pH = 6.0) batch cultures with Lactobacillus rhamnosus RW-9595M, using a central composite design (CCD). The EPS production was measured using both the conventional method based on ethanol precipitation of EPS and a new ultrafiltration (UF) method. EPS production was not growth-associated for high temperatures (32,42 °C) and WP concentrations (7.0,8.4%). In contrast, at suboptimal temperature (22,26 °C), EPS production was growth-associated. Maximal EPS production measured with the UF method was approximately 2-fold higher than those measured with the conventional method and varied from 125 to 477 mg/L. This parameter was significantly influenced by WP and YNB*WP interaction, whereas ANOVA for maximal EPS production measured by the conventional method did not show significant factor effects. EPS volumetric productivities varied from 3.0 to 16.4 mg EPS/L·h. YNB supplementation did not promote cell growth but did increase EPS production at high WP concentrations. Our data indicate the potential of L. rhamnosus RW-9595M for producing EPS in a supplemented WP medium and suggest that this production could be further increased by the addition of a growth-limiting nutrient in the medium. [source] Optimisation of the medium composition for production of protease and soybean peptides by Bacillus subtilis SHZ using response surface methodologyINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2008Bo Yu Summary Responses surface methodology was employed to enhance the production of protease and soybean peptides by Bacillus subtilis SHZ. For screening of medium composition significantly influencing protease and soybean peptides yield, the two-level Plackett,Burman design was used. Among thirteen variables tested; KH2PO4, glucose and defatted soybean flour (DSF) were selected based on their high significant effect on both protease activity and soybean peptides yield. Then, a three-level Box,Behnken design was employed to optimise the medium composition for the production of the protease and soybean peptides in submerged fermentation. Mathematical models were then developed to show the effect of each medium composition and their interactions on the production of protease and soybean peptides. The model estimated that, the maximal protease activity (320 ± 1 U mL,1) could be obtained when the concentrations of glucose, KH2PO4, DSF were set at 8,9 g L,1, 2,3 g L,1, 55,65 g L,1, respectively; while a maximal yield of soybean peptides (8.5 ± 0.1 g L,1) could be achieved when the concentrations of glucose, KH2PO4, DSF were set at 7,9 g L,1, 3,4 g L,1 and 55,58 g L,1, respectively. These predicted values were also verified by validation experiments. [source] Influence of culture conditions on laccase production and isozyme patterns in the white-rot fungus Trametes gallicaJOURNAL OF BASIC MICROBIOLOGY, Issue 3 2005Jia Li Dong Laccase production by the white-rot fungus Trametes gallica was studied, using twelve different media under static or shaking condition. The results indicated that organic nitrogen sources such as tryptone and peptone strongly improved laccase production. The application of an amino acid mixture and a lignin preparation also increased the formation of laccase, which was not observed in the presence of potato extract. Native polyacryl amide gel electrophoresis (PAGE) followed by laccase activity staining using guaiacol as the substrate was performed to analyze the laccase isozyme patterns under the different culture conditions employed. Zymograms revealed a total of twenty different laccase activity bands that appeared in individual patterns, dependent on the respective culture condition applied. This indicates that both the medium composition and the mode of incubation (static or shaking) influenced the laccase isozyme gene expression. This was the first time to report so many laccase isozymes in a fungus. Native PAGE with silver staining showed that laccases were the main protein productions in several media providing a potentially convenient way in purifying laccases from T. gallica. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimization of agro-residual medium for ,-amylase production from a hyper-producing Bacillus subtilis KCC103 in submerged fermentationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2009Gobinath Rajagopalan Abstract BACKGROUND: Although submerged fermentation (SmF) is the conventional method in industry, use of low-cost agro-residues for ,-amylase production in SmF has not been well established. Here we optimized agro-residue-based medium and culture conditions for ,-amylase production in SmF using a hyper-producing Bacillus subtilis KCC103. RESULTS:B. subtilis KCC103 produced ,-amylase in SmF by utilizing agro-residues. Wheat bran (WB) and sunflower oil cake (SFOC) were selected as the best substrates using shake flasks. Medium containing WB (carbohydrate rich) and SFOC (rich in protein and free amino acids) at 1:1 (w/w) ratio produced high levels (90 IU mL,1) of ,-amylase at 30,36 h in a shake flask. The ,-amylase yield was 14-fold enhanced (1258 IU mL,1) by optimizing process parameters and medium composition following response surface methodology in a bioreactor. The optimal conditions were: WB 1.27%, SFOC 1.42%, pH 7, 37 °C and 10,12 h. Both in shake flask and bioreactor ,-amylase synthesis was not repressed by the release of simple sugars into the medium. CONCLUSION: KCC103 with catabolite derepression and hyperproducing ability is useful for economic ,-amylase production using low-cost agro-residual substrates in conventional SmF. Since the production time (10,12 h) is much shorter than other strains this would improve productivity and further reduce the cost of ,-amylase production. Copyright © 2008 Society of Chemical Industry [source] Batch production of L(+) lactic acid from whey by Lactobacillus casei (NRRL B-441)JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2004Ali O Büyükkileci Abstract The effects of temperature, pH, and medium composition on lactic acid production by Lactobacillus casei were investigated. The highest lactic acid productivity values were obtained at 37 °C and pH 5.5. The productivity was 1.87 g dm,3 h,1 at 37 °C in shake flasks. In the fermenter, a productivity of 3.97 g dm,3 h,1 was obtained at pH 5.5. The most appropriate yeast extract concentration was 5.0 g dm,3. Whey yielded a higher productivity value than the analytical lactose and glucose. Initial whey lactose concentration did not affect lactic acid productivity. MnSO4 ·H2O was necessary for lactic acid production by L casei from whey. Product yields were approximately 0.93 g lactic acid g lactose,1. Copyright © 2004 Society of Chemical Industry [source] Scale-up from shake flasks to fermenters in batch and continuous mode with Corynebacterium glutamicum on lactic acid based on oxygen transfer and pHBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2007Juri M. Seletzky Abstract Scale-up from shake flasks to fermenters has been hampered by the lack of knowledge concerning the influence of operating conditions on mass transfer, hydromechanics, and power input. However, in recent years the properties of shake flasks have been described with empirical models. A practical scale-up strategy for everyday use is introduced for the scale-up of aerobic cultures from shake flasks to fermenters in batch and continuous mode. The strategy is based on empirical correlations of the volumetric mass transfer coefficient (kLa) and the pH. The accuracy of the empirical kLa correlations and the assumptions required to use these correlations for an arbitrary biological medium are discussed. To determine the optimal pH of the culture medium a simple laboratory method based on titration curves of the medium and a mechanistic pH model, which is solely based on the medium composition, is applied. The effectiveness of the scale-up strategy is demonstrated by comparing the behavior of Corynebacterium glutamicum on lactic acid in shake flasks and fermenters in batch and continuous mode. The maximum growth rate (µmax,=,0.32 h,1) and the oxygen substrate coefficient (,=,0.0174 mol/l) of C. glutamicum on lactic acid were equal for shake flask, fermenter, batch, and continuous cultures. The biomass substrate yield was independent of the scale, but was lower in batch cultures (YX/S,=,0.36 g/g) than in continuous cultures (YX/S,=,0.45 g/g). The experimental data (biomass, respiration, pH) could be described with a simple biological model combined with a mechanistic pH model. Biotechnol. Bioeng. 2007; 98: 800,811. © 2007 Wiley Periodicals, Inc. [source] Optimization of medium composition for the production of antimicrobial activity by Bacillus subtilis B38BIOTECHNOLOGY PROGRESS, Issue 5 2009Olfa Tabbene Abstract An antimicrobial activity produced by Bacillus subtilis B38 was found to be effective against several bacteria, including pathogenic and spoilage microorganisms such as, Listeria monocytogenes, Salmonella enteridis, and clinical isolates of methicillin-resistant Staphylococcus species. Nutrients such as carbon, nitrogen sources, and inorganic salts enhanced the production level of the antibacterial activity by B. subtilis B38. A first screening step showed that lactose, ammonium succinate, and manganese most influenced both cell growth and antibacterial activity production. These three factors varied at two levels in eight experiments using full factorial design. Results indicated that maximum cell growth (OD = 10.2) and maximum production of antibacterial activity (360 AU/mL) were obtained in a modified medium containing 1.5% (w/v) lactose, 0.15% (w/v) ammonium succinate, and 0.3 mg/L manganese. Depending on the indicator strain used, the antibacterial activity was 2- to 4-fold higher in the modified culture medium than in TSB medium under the same conditions. Thin layer chromatography-bioautography assay showed the presence of three active spots with Rf values of 0.47, 0.7, and 0.82 in TSB medium. However, the inhibition zone of two spots (Rf values of 0.7 and 0.82) was slightly larger in the modified medium. Moreover, a large zone of inhibition with an Rf value of 0.3, was observed in this modified medium, instead of the spot having an Rf value of 0.47. These results suggest that the nutrients act as environmental factors, quantitatively and qualitatively affecting the production of antibacterial compounds by B. subtilis B38. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Heterologous Expression of Vitreoscilla Hemoglobin (VHb) and Cultivation Conditions Affect the Alkaloid Profile of Hyoscyamus muticus Hairy RootsBIOTECHNOLOGY PROGRESS, Issue 2 2006Annika Wilhelmson Fast-growing hairy root cultures of Hyoscyamus muticus induced by Agrobacterium rhizogenes offer a potential production system for tropane alkaloids. Oxygen deficiency has been shown to limit growth and biomass accumulation of hairy roots, whereas little experimental data is available on the effect of oxygen on alkaloid production. We have investigated the effect of Vitreoscilla hemoglobin (VHb) expression and cultivation conditions on the complete alkaloid profile of H. muticus hairy roots in shake flasks and in a laboratory scale bioreactor. We optimized the growth medium composition and studied the effects of sucrose, ammonium, nitrate, and phosphate on growth and alkaloid production. Maximum biomass accumulation was achieved with the highest and maximum hyoscyamine content with the lowest sucrose concentration. The optimum nitrate concentration for growth was higher for the VHb line than the control. Neither VHb expression nor aeration improved the hyoscyamine content significantly, thus suggesting that hyoscyamine biosynthesis is not limited by oxygen availability. Interestingly, the effect of VHb expression on the alkaloid profile was slightly different from that of aeration. VHb expression did not affect the concentrations of cuscohygrine, which was increased by aeration. Therefore, the effect of VHb is probably not related only to its ability to increase the intracellular effective oxygen concentration. [source] Cell Cycle Progression in Serum-Free Cultures of Sf9 Insect Cells: Modulation by Conditioned Medium Factors and Implications for Proliferation and Productivity,BIOTECHNOLOGY PROGRESS, Issue 5 2000Magnus Doverskog Cell cycle progression was studied in serum-free batch cultures of Spodoptera frugiperda (Sf9) insect cells, and the implications for proliferation and productivity were investigated. Cell cycle dynamics in KBM10 serum-free medium was characterized by an accumulation of 50,70% of the cells in the G2/M phase of the cell cycle during the first 24 h after inoculation. Following the cell cycle arrest, the cell population was redistributed into G1 and in particular into the S phase. Maximum rate of proliferation (,N,max) was reached 24,48 h after the release from cell cycle arrest, coinciding with a minimum distribution of cells in the G2/M phase. The following declining ,N could be explained by a slow increase in the G2/M cell population. However, at approximately 100 h, an abrupt increase in the amount of G2/M cells occurred. This switch occurred at about the same time point and cell density, irrespective of medium composition and maximum cell density. An octaploid population evolved from G2/M arrested cells, showing the occurrence of endoreplication in this cell line. In addition, conditioned medium factor(s) were found to increase ,N,max, decrease the time to reach ,N,max, and decrease the synchronization of cells in G2/M during the lag and growth phase. A conditioned medium factor appears to be a small peptide. On basis of these results we suggest that the observed cell cycle dynamics is the result of autoregulatory events occurring at key points during the course of a culture, and that entry into mitosis is the target for regulation. Infecting the Sf9 cells with recombinant baculovirus resulted in a linear increase in volumetric productivity of ,-galactosidase up to 68,75 h of culture. Beyond this point almost no product was formed. Medium renewal at the time of infection could only partly restore the lost hypertrophy and product yield of cultures infected after the transition point. The critical time of infection correlated to the time when the mean population cell volume had attained a minimum, and this occurred 24 h before the switch into the G2/M phase. We suggest that the cell density dependent decrease in productivity ultimately depends on the autoregulatory events leading to G2/M cell cycle arrest. [source] Microwave-Assisted Functionalization of Carbon Nanostructures in Ionic LiquidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 46 2009Ivan Guryanov Dr. Abstract The effect of microwave (MW) irradiation and ionic liquids (IL) on the cycloaddition of azomethine ylides to [60]fullerene has been investigated by screening the reaction protocol with regard to the IL medium composition, the applied MW power, and the simultaneous cooling of the system. [60]Fullerene conversion up to 98,% is achieved in 2,10,min, by using a 1:3 mixture of the IL 1-methyl-3- n -octyl imidazolium tetrafluoroborate ([omim]BF4) and o -dichlorobenzene, and an applied power as low as 12,W. The mono- versus poly-addition selectivity to [60]fullerene can be tuned as a function of fullerene concentration. The reaction scope includes aliphatic, aromatic, and fluorous-tagged (FT) derivatives. MW irradiation of IL-structured bucky gels is instrumental for the functionalization of single-walled carbon nanotubes (SWNTs), yielding group coverages of up to one functional group per 60 carbon atoms of the SWNT network. An improved performance is obtained in low viscosity bucky gels, in the order [bmim]BF4> [omim]BF4> [hvim]TF2N (bmim=1-methyl-3- n -butyl imidazolium; hvim=1-vinyl-3- n -hexadecyl imidazolium). With this protocol, the introduction of fluorous-tagged pyrrolidine moieties onto the SWNT surface (1/108 functional coverage) yields novel FT-CNS (carbon nanostructures) with high affinity for fluorinated phases. [source] Thermodynamic Analysis of Energy Transfer in Acidogenic CulturesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2008J.-R. Bastidas-Oyanedel Abstract A global thermodynamic analysis, normally used for pure cultures, has been performed for steady-state data sets from acidogenic mixed cultures. This analysis is a combination of two different thermodynamic approaches, based on tabulated standard Gibbs energy of formation, global stoichiometry and medium compositions. It takes into account the energy transfer efficiency, ,, together with the Gibbs free energy dissipation, ,Go, analysis of the different data. The objective is to describe these systems thermodynamically without any heat measurement. The results show that , is influenced by environmental conditions, where increasing hydraulic retention time increases its value all cases. The pH effect on , is related to metabolic shifts and osmoregulation. Within the environmental conditions analyzed, , ranges from 0.23 for a hydraulic retention time of 20,h and pH,4, to 0.42 for a hydraulic retention time of 8,h and a pH ranging from 7,8.5. The estimated values of ,Go are comparable to standard Gibbs energy of dissipation reported in the literature. For the data sets analyzed, ,Go ranges from ,1210,kJ/molx, corresponding to a stirring velocity of 300,rpm, pH,6 and a hydraulic retention time of 6,h, to ,20744,kJ/molx for pH,4 and a hydraulic retention time of 20,h. For average conclusions, the combined approach based on standard Gibbs energy of formation and global stoichiometry, used in this thermodynamic analysis, allows for the estimation of Gibbs energy dissipation values from the extracellular medium compositions in acidogenic mixed cultures. Such estimated values are comparable to the standard Gibbs energy dissipation values reported in the literature. It is demonstrated that , is affected by the environmental conditions, i.e., stirring velocity, hydraulic retention time and pH. However, a relationship that relates this parameter to environmental conditions was not found and will be the focus of further research. [source] | |||||||||||||