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Initial Glucose Concentration (initial + glucose_concentration)
Selected AbstractsAerobic degradation by white-rot fungi of trichloroethylene (TCE) and mixtures of TCE and perchloroethylene (PCE)JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2008Ernest Marco-Urrea Abstract BACKGROUND: Trichloroethylene (TCE) and perchloroethylene (PCE) are considered among the most important groundwater pollutants around the world. These compounds are usually found together in polluted environments but little is known about the ability of microorganisms to simultaneously degrade TCE and PCE. RESULTS: Data showed that several species of white-rot fungi, including Trametes versicolor, Ganoderma lucidum, and Irpex lacteus, degrade substantial levels of TCE in pure culture. T. versicolor was chosen for further study since it degraded higher levels of TCE than the other organisms. Initial glucose concentration and reoxygenation of samples increased the amount of TCE dechlorination, but no significant difference in percentage TCE degradation was observed. T. versicolor was able to degrade 34.1 and 47.7% of PCE and TCE added as mixtures (containing 5 and 10 mg L,1, respectively). CONCLUSIONS: The degradation ability of TCE was extended to other species of white-rot fungi. Percentage degradation as well as chloride release from mixtures of TCE and PCE showed that T. versicolor degrades mixtures of TCE and PCE almost as well as its ability to degrade individually added TCE or PCE. The results suggest the potential promise of T. versicolor for bioremediation of TCE and PCE in the environment. Copyright © 2008 Society of Chemical Industry [source] Suspension Culture Process of MethA Tumor Cell for the Production of Heat-Shock Protein Glycoprotein 96: Process Optimization in Spinner FlasksBIOTECHNOLOGY PROGRESS, Issue 6 2007Ya-Jie Tang Heat-shock proteins (HSPs) act like "chaperones", making sure that the cellapos;s proteins are in the right shape and in the right place at the right time. Heat-shock protein glycoprotein 96 (gp96) is a member of the HSP90 protein family, which chaperones a number of molecules in protein folding and transportation. Heat-shock protein gp96 serves as a natural adjuvant for chaperoning antigenic peptides into the immune surveillance pathways. Currently, heat-shock protein gp96 was only isolated from murine and human tissues and cell lines. An animal cell suspension culture process for the production of heat-shock protein gp96 by MethA tumor cell was developed for the first time in spinner flasks. Effects of culture medium and condition were studied to enhance the MethA tumor cell density and the production and productivity of heat-shock protein gp96. Initial glucose concentration had a significant effect on the heat-shock protein gp96 accumulation, and an initial glucose level of 7.0 g/L was desirable for MethA tumor cell growth and heat-shock protein gp96 production and productivity. Cultures at an initial glutamine concentration of 3 and 6 mM were nutritionally limited by glutamine. At an initial glutamine concentration of 6 mM, the maximal viable cell density of 19.90 × 105 cells/mL and the maximal heat-shock protein gp96 production of 4.95 mg/L was obtained. The initial concentration of RPMI 1640 and serum greatly affected the MethA tumor cell culture process. Specifically cultures with lower initial concentration of RPMI 1640 resulted in lower viable cell density and lower heat-shock protein gp96 production. At an initial serum concentration of 8%, the maximal viable cell density of 19.18 × 105 cells/mL and the maximal heat-shock protein gp96 production of 5.67 mg/L was obtained. The spin rate significantly affected the cell culture process in spinner flasks, and a spin rate of 150 rpm was desirable for MethA tumor cell growth and heat-shock protein gp96 production and productivity. Not only the cell density but also the production and productivity of heat-shock protein gp96 attained in this work are the highest reported in the culture of MethA tumor cell. This work offers an effective approach for producing heat-shock protein glycoprotein 96 from the cell culture process. The fundamental information obtained in this study may be useful for the efficient production of heat-shock protein by animal cell suspension culture on a large scale. [source] Reversible transition between active and dormant microbial states in soilFEMS MICROBIOLOGY ECOLOGY, Issue 2-3 2001John Stenström Abstract The rate of respiration obtained in the substrate-induced respiration (SIR) method can be divided into the respiration rate of growing (r) and non-growing (K) microorganisms. The fraction of r is generally small (5,20%) in soils with no recent addition of substrates, but can be 100% in soils with high substrate availability. This suggests that substrate availability determines the proportion of biomass between these groups, and implies that transitions between them can take place reversibly. These hypotheses were tested by adding three different amounts of glucose which induced first-order, zero-order, and growth-associated respiration kinetics to three soils at four pre-incubation times (4, 12, 27, and 46 days) before the SIR measurement. An abiotic flush of CO2 in the SIR measurement was detected and corrected for before data analysis. Accumulated CO2 -C over 4 days after glucose addition, corrected for the respiration in unamended controls, corresponded to 41,50% mineralization of the glucose-C, and the relative amount mineralized by each soil was independent of the glucose amount added. The high glucose concentration gave an increased SIR, which reverted to the initial value within 27,46 days. In a specific sample, the maximum respiration rate induced during the pre-incubation, and the amount of organisms transformed from the K to the r state, as quantified in respiration rate units in the SIR measurement, were identical to each other, and these parameters were also highly correlated to the initial glucose concentration. The K,r transition was very fast, probably concurrent with the instantaneous increase in the respiration rate obtained by the glucose amendment. Thereafter, a slow first-order back-transition from the r to the K state ensued, with half-lives of 12, 23, and 70 days for the three soils. The results suggest the existence of community-level controls by which growth within or of the whole biomass is inhibited until it has been completely transformed into the r state. The data also suggest that the microbial specific activity is not related to the availability of exogenous substrate in a continuous fashion, rather it responds as a sharp transition between dormant and fully active. Furthermore, the inherent physiological state of the microbial biomass is strongly related to its history. It is proposed that the normal dynamics of the soil microbial biomass is an oscillation between active and dormant physiological states, while significant growth occurs only at substantial substrate amendment. [source] Effects of glucose and nitrogen source concentration on batch fermentation kinetics of Lactococcus lactis under hemin-stimulated respirative conditionBIOTECHNOLOGY PROGRESS, Issue 4 2008Azher Razvi Abstract Analytical solutions to the ordinary differential equations governing the kinetics of cell growth, substrate utilization, and product formation of batch fermentation processes were derived and used to study the kinetics of the hemin-stimulated respiratory cultivation of Lactococcus lactis at varied initial glucose concentrations and nitrogen source concentrations. Studies revealed that initial glucose concentration varying in the range of 60 to 90 g/L had no significant substrate inhibitive effect. Furthermore, elevating the concentration of complex nitrogen sources while maintaining glucose concentration at 60% led to a high final biomass concentration of 6.6 g/L, substantially higher than that obtained with the basic medium, which was 4.1 g/L. [source] | ||||||||||