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Inhibition Coefficient (inhibition + coefficient)
Selected AbstractsA kinetic evaluation of the anaerobic digestion of two-phase olive mill effluent in batch reactorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2005Francisco Raposo Abstract A comparative kinetic study was carried out on the anaerobic digestion of two-phase olive mill effluent (TPOME) using three 1-dm3 volume stirred tank reactors, one with freely suspended biomass (control), and the other two with biomass supported on polyvinyl chloride (PVC) and bentonite (aluminium silicate), respectively. The reactors were batch fed at mesophilic temperature (35 °C) using volumes of TPOME of between 50 and 600 cm3, corresponding to chemical oxygen demand (COD) loadings in the range of 1.02,14.22 g, respectively. The process followed first-order kinetics and the specific rate constants, K0, were calculated. The K0 values decreased considerably from 2.59 to 0.14 d,1, from 1.93 to 0.23 d,1 and from 1.52 to 0.17 d,1 for the reactors with suspended biomass (control) and biomass immobilized on PVC and bentonite, respectively, when the COD loadings increased from 1.02 to 14.22 g; this showed an inhibition phenomenon in the three reactors studied. The values of the critical inhibitory substrate concentration (S*), theoretical kinetic constant without inhibition (KA) and the inhibition coefficient or inhibitory parameter for each reactor (n) were determined using the Levenspiel model. Copyright © 2004 Society of Chemical Industry [source] Substrate inhibition of Pediococcus acidilactici by glucose on a waste medium.LETTERS IN APPLIED MICROBIOLOGY, Issue 5 2003Simulations, experimental results Abstract Aims: The possibility of substrate inhibition by glucose on biomass and pediocin production was studied in cultures of Pediococcus acidilactici on a residual medium. Methods and Results: Calculation of the substrate inhibition coefficient in the context of microbial growth is generally laborious, and very prone to experimental error. However, a simulation combining logistic and Monod kinetics equations demonstrates that quantitative evidence for this type of inhibition, without the possibility of misinterpretation, can be obtained through the comparison of punctual preasymptotic productions as a function of substrate concentration. Significance and Impact of the Study: It was concluded that glucose had an inhibitory effect on growth, but not on bacteriocin production. [source] Sugarcane ShSUT1: analysis of sucrose transport activity and inhibition by sucralosePLANT CELL & ENVIRONMENT, Issue 10 2006ANKE REINDERS ABSTRACT Plant sucrose transporters (SUTs) are members of the glycoside-pentoside-hexuronide (GPH) cation symporter family (TC2.A.2) that is part of the major facilitator superfamily (MFS). All plant SUTs characterized to date function as proton-coupled symporters and catalyze the cellular uptake of sucrose. SUTs are involved in loading sucrose into the phloem and sink tissues, such as seeds, roots and flowers. Because monocots are agriculturally important, SUTs from cereals have been the focus of recent research. Here we present a functional analysis of the SUT ShSUT1 from sugarcane, an important crop species grown for its ability to accumulate high amounts of sucrose in the stem. ShSUT1 was previously shown to be expressed in maturing stems and plays an important role in the accumulation of sucrose in this tissue. Using two-electrode voltage clamping in Xenopus oocytes expressing ShSUT1, we found that ShSUT1 is highly selective for sucrose, but has a relatively low affinity for sucrose (K0.5 = 8.26 mM at pH 5.6 and a membrane potential of ,137 mV). We also found that the sucrose analog sucralose (4,1,,6,-trichloro-4,1,,6,-trideoxy-galacto-sucrose) is a competitive inhibitor of ShSUT1 with an inhibition coefficient (Ki) of 16.5 mM. The presented data contribute to our understanding of sucrose transport in plants in general and in monocots in particular. [source] Ferrous iron oxidation by foam immobilized Acidithiobacillus ferrooxidans: Experiments and modelingBIOTECHNOLOGY PROGRESS, Issue 5 2009S. Jaisankar Abstract Ferrous iron bio-oxidation by Acidithiobacillus ferrooxidans immobilized on polyurethane foam was investigated. Cells were immobilized on foams by placing them in a growth environment and fully bacterially activated polyurethane foams (BAPUFs) were prepared by serial subculturing in batches with partially bacterially activated foam (pBAPUFs). The dependence of foam density on cell immobilization process, the effect of pH and BAPUF loading on ferrous oxidation were studied to choose operating parameters for continuous operations. With an objective to have high cell densities both in foam and the liquid phase, pretreated foams of density 50 kg/m3 as cell support and ferrous oxidation at pH 1.5 to moderate the ferric precipitation were preferred. A novel basket-type bioreactor for continuous ferrous iron oxidation, which features a multiple effect of stirred tank in combination with recirculation, was designed and operated. The results were compared with that of a free cell and a sheet-type foam immobilized reactors. A fivefold increase in ferric iron productivity at 33.02 g/h/L of free volume in foam was achieved using basket-type bioreactor when compared to a free cell continuous system. A mathematical model for ferrous iron oxidation by Acidithiobacillus ferrooxidans cells immobilized on polyurethane foam was developed with cell growth in foam accounted by an effectiveness factor. The basic parameters of simulation were estimated using the experimental data on free cell growth as well as from cell attachment to foam under nongrowing conditions. The model predicted the phase of both oxidation of ferrous in shake flasks by pBAPUFs as well as by fully activated BAPUFs for different cell loadings in foam. Model for stirred tank basket bioreactor predicted within 5% both transient and steady state of the experiments closely for the simulated dilution rates. Bio-oxidation at high Fe2+ concentrations were simulated with experiments when substrate and product inhibition coefficients were factored into cell growth kinetics. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||