嗜酸氧化亚铁硫杆菌生长动力学

在确定二价铁离子为A.f生长过程中惟一限制性底物条件下,通过考察初始亚铁离子浓度、初始pH值两种影响亚铁离子氧化代谢的主要因素来研究细菌的生长特性,得到以限制性底物亚铁离子浓度为表征的细菌生长曲线。利用基于Monod方程建立的细菌生长动力学方程模型,采用Matlab软件中的Gauss-Newton算法确定了在不同条件下细菌生长动力学参数,包括最大比生长速率μm、Monod常数K及Ro,推导出了不同条件下A.f对数期以底物Fe(Ⅱ)浓度为表征的生长动力学方程。     

嗜酸氧化亚铁硫杆菌生长动力学方程的应用

基于Monod模型推导出了A．f的生长动力学方程模型,采用Gauss-Newton算法确定了在不同初始条件下细菌生长的动力学参数,即最大比生长速率‰、Monod常数K及R0。通过在不同初始条件下细菌生长特性的研究,得到了相应初始生长条件下以限制性底物亚铁离子浓度为表征的生长动力学方程,理论上揭示了动力学参数变化对细菌生长的影响规律,其中生长动力学方程的数值模拟与实验数据相吻合。     

磷限制下大型海藻与微藻间资源竞争理论的实验验证

用一次性培养法结合Monod方程测得海洋微藻-亚心型扁藻(Tetraselmis subcordiformis (Wile) Hazen)与大型海藻-孔石莼(Ulva pertusa Kjellm.)磷限制下的生长动力参数.孔石莼具有较低的半饱和生长常数及最大生长率,其分别为0.016 μmol/L和0.16 d-1,而亚心型扁藻的半饱和生长常数和最大生长率分别是0.021 μmol/L 和0.83 d-1. 两种藻类间的营养竞争实验采用半连续培养法在磷限制条件下进行,实验过程中,分别对两者施予相同或不同的去除率,使两者享有相同或不同的资源需求值R*.由Monod方程所作的竞争预测与实验观察结果的比较显示:仅在两种藻类间的资源需求值R*差异显著(t检验,P＜0.01)时,Monod方程才能对竞争结果作出较为准确的预测;在两种藻类享有相同的资源需求值R*时,亚心型扁藻在竞争中取代孔石莼.Monod模型仅能部分预测大型海藻与海洋微藻间的竞争结果.     

磷限制下大型海藻与微藻间资源竞争理论的实验验证(英文)

用一次性培养法结合Monod方程测得海洋微藻_亚心型扁藻 (Tetraselmissubcordiformis (Wile)Hazen)与大型海藻_孔石莼 (UlvapertusaKjellm .)磷限制下的生长动力参数。孔石莼具有较低的半饱和生长常数及最大生长率 ,其分别为 0 .0 16 μmol/L和 0 .16d-1,而亚心型扁藻的半饱和生长常数和最大生长率分别是 0 .0 2 1μmol/L和 0 .83d-1。两种藻类间的营养竞争实验采用半连续培养法在磷限制条件下进行 ,实验过程中 ,分别对两者施予相同或不同的去除率 ,使两者享有相同或不同的资源需求值R 。由Monod方程所作的竞争预测与实验观察结果的比较显示 :仅在两种藻类间的资源需求值R 差异显著 (t检验 ,P <0 .0 1)时 ,Monod方程才能对竞争结果作出较为准确的预测 ;在两种藻类享有相同的资源需求值R 时 ,亚心型扁藻在竞争中取代孔石莼。Monod模型仅能部分预测大型海藻与海洋微藻间的竞争结果。     

磷限制下大型海灌与微灌间资源竞争理论的实验验证

用一次性培养结合Monod方程测得海洋微藻－亚心型扁藻（Tetraselmis subcordiformis(Wile)Hazen)与大型海藻－孔石莼（Ulva pertusa Kjellm.)磷限制下的生长动力参数。孔石莼具有较低的半饱和生长常数及最大生长率,其分别为0．016μmol/L和0．16d^-1,而亚心型扁藻的半饱和生长常数和最大生长率分别是0．021μmol/L和0.83d^-1。两种藻类间的营养竞争实验采用半连续培养法在磷限制制条件下进行,实验过程中,分别对两者施予相同或不同的去除率,使两者享有相同或不同的资源需求值R^*。由Monod方程所作的竞争预测与实验观察结果的比较显示：仅在两种藻类间的资源需求值R^*差异显著（t检验,P＜0．01）时,Monod方程才能对竞争结果作出较为准确的预测;在两种藻类享的相同的资源需求值R^*时,亚心型扁藻在竞争中取代孔石莼。Monod模型仅能部分预测大型海藻与海洋微藻间的竞争结果。     

类球红细菌分批发酵生产辅酶Q_(10)的动力学模型

研究了Rhodobacter sphaeroidesEIM-8发酵生产CoQ_(10)的代谢特性.根据Monod、Logistic和Luedeking-Piret方程建立菌体细胞生长、CoQ_(10)积累和葡萄糖消耗的动力学模型,并采用进化规划求得模型参数.模型模拟计算结果与试验值拟合良好,平均相对误差均在7%以内,较好地反映了类球红细菌分批发酵过程的动力学特征.     

以营养动力学为基础的种群和生态系统数学模型的结构

本文试图从营养动力学的角度讨论单种群、捕食者-食饵系统、食物链的数学模型和种群的营养结构形式。一、单种群的增殖在一封闭的有限营养的单种微生物种群系统中,Monod方程为     

732树脂吸附蛋白质的机理研究

通过树脂吸附水溶液中蛋白质的试验 ,研究了 732树脂对蛋白质吸附过程机理 ,初步分析了动力学行为 ,包括吸附等温线方程、吸附速率方程、总传质系数、树脂内的有效扩散系数等     

基于遗传算法的羊肚菌液体发酵动力学模型的建立

发酵动力学研究是实现发酵过程最优化控制及发酵过程放大的前提条件。本研究对羊肚菌液体深层发酵动力学进行了研究, 在Matlab软件平台上, 应用遗传算法对比了真菌生长较常用的Monod与Logistic方程在描述羊肚菌生长动力学时的优劣, 并对羊肚菌的生长、胞外多糖产生和基质消耗模型进行了参数估计。结果表明, Logistic方程与试验数据拟和情况更好, 并给出了羊肚菌液体深层发酵的动力学模型具体形式, 经验证, 模型的平均误差为5.8%。利用遗传算法选择羊肚菌动力学模型, 并进行参数估计与其他方法相比具有快速、搜索面广、接近全局最优解的特点, 在处理分批发酵动力学问题上具有不可比拟的优势, 发酵动力学模型的建立为发酵过程优化及放大奠定了基础。     

短梗霉多糖发酵过程特征的研究

本文针对短梗霉多糖发酵过程,经研究建立了基于逻辑方程和Luedeking—Piret方程的动力学模型： dx／dt=肛x(1一x／xm) dP／dt=m1x十m2(dx/dt) ds／dt=-b1x-b2(dx／dt)-b3(dP／dt) 其流变特性由初始时的牛顿流体转变为典型的假塑性非牛顿流体并遵从指数方程,即：τ=Kγn随发酵过程进行,发酵液的表观粘度增大,体积氧传质系数减小。搅拌转速的增加有利于提高体积氧传质系数。流变指数n、稠度系数K、气液传质系数Kla。与菌体浓度x、多糖浓度P、搅拌转速N及表观粘度ηa间分别有如下经验方程; k=1．2×10-2X2.43 n=0．461(P／Pm)0.07(x／xm)0.216 KLaDi2=1．48×104(D:N2)0.71(ηW)0.15 Dg ηa     

Re-interpretation of the logistic equation for batch microbial growth in relation to Monod kinetics

Aims:  To determine the underlying substrate utilization mechanism in the logistic equation for batch microbial growth by revealing the relationship between the logistic and Monod kinetics. Also, to determine the logistic rate constant in terms of Monod kinetic constants.
Methods and Results:  The logistic equation used to describe batch microbial growth was related to the Monod kinetics and found to be first-order in terms of the substrate and biomass concentrations. The logistic equation constant was also related to the Monod kinetic constants. Similarly, the substrate utilization kinetic equations were derived by using the logistic growth equation and related to the Monod kinetics.
Conclusion:  It is revaled that the logistic growth equation is a special form of the Monod growth kinetics when substrate limitation is first-order with respect to the substrate concentration. The logistic rate constant ( k ) is directly proportional to the maximum specific growth rate constant ( μ _m) and initial substrate concentration ( S ₀) and also inversely related to the saturation constant ( K _s).
Significance and Impact of the Study:  The semi-empirical logistic equation can be used instead of Monod kinetics at low substrate concentrations to describe batch microbial growth using the relationship between the logistic rate constant and the Monod kinetic constants.     

The removal of nitrogen and organics in vertical flow wetland reactors: predictive models

Three kinetic models, for predicting the removal of nitrogen and organics in vertical flow wetlands, have been developed and evaluated. These models were established by combining first-order, Monod and multiple Monod kinetics with continuous stirred-tank reactor (CSTR) flow pattern. Critical evaluations of these models using three statistical parameters, coefficient of determination, relative root mean square error and model efficiency, indicated that when the Monod/multiple Monod kinetics was combined with CSTR flow pattern it allowed close match between theoretical prediction and experiment data of nitrogen and organics removal. The kinetic coefficients (derived from Monod/multiple Monod kinetics) was found to increase with pollutant loading, indicating that the coefficients may vary based on different factors, such as influent pollutant concentration, hydraulic loading, and water depth. Overall, this study demonstrated the validity of combining Monod and multiple Monod kinetics with CSTR flow pattern for the modelling and design of vertical flow wetland systems.     

Nonlinear estimation of the parameters of Monod kinetics that best describe mineralization of several substrate concentrations by dissimilar bacterial densities

The kinetics of mineralization of a wide range of concentrations of benzoate, glucose, and benzylamine by Pseudomonas sp., Salmonella typhimurium, and microorganisms in acclimated sewage was studied. The treatment of initial substrate concentration and population density as independent variables in nonlinear regression analysis permitted the estimation of a single value for each of the parameters of Monod kinetics that best described the mineralization of substrate at each concentration by the pure cultures and the sewage microflora. One value for each of the parameters of Monod kinetics was used for each of the three compounds to produce theoretical curves which lay close to the observed data on mineralization. Statistically significant differences existed in the values of the parameters of Monod kinetics that best described mineralization in cultures differing only in initial substrate concentration and cell density. However, for the compounds tested, the variance left by analyses using one value for each parameter of Monod kinetics was less than double the unexplained variance left by individual analyses of the data from each treatment. Although significant, this increase is small compared with the amount of variance that could be explained using only one value for each parameter of Monod kinetics.     

Nonlinear estimation of the parameters of Monod kinetics that best describe mineralization of several substrate concentrations by dissimilar bacterial densities.

The kinetics of mineralization of a wide range of concentrations of benzoate, glucose, and benzylamine by Pseudomonas sp., Salmonella typhimurium, and microorganisms in acclimated sewage was studied. The treatment of initial substrate concentration and population density as independent variables in nonlinear regression analysis permitted the estimation of a single value for each of the parameters of Monod kinetics that best described the mineralization of substrate at each concentration by the pure cultures and the sewage microflora. One value for each of the parameters of Monod kinetics was used for each of the three compounds to produce theoretical curves which lay close to the observed data on mineralization. Statistically significant differences existed in the values of the parameters of Monod kinetics that best described mineralization in cultures differing only in initial substrate concentration and cell density. However, for the compounds tested, the variance left by analyses using one value for each parameter of Monod kinetics was less than double the unexplained variance left by individual analyses of the data from each treatment. Although significant, this increase is small compared with the amount of variance that could be explained using only one value for each parameter of Monod kinetics.     

Models for mineralization kinetics with the variables of substrate concentration and population density.

The rates of mineralization of [14C]benzoate by an induced population of Pseudomonas sp. were measured at initial substrate concentrations ranging from 10 ng/ml to 100 micrograms/ml. Plots of the radioactivity remaining in the culture were fit by nonlinear regression to six kinetic models derived from the Monod equation. These models incorporate only the variables of substrate concentration and cell density. Plots of the mineralization kinetics in cultures containing low, intermediate, and high initial substrate concentrations were well fit by first-order, integrated Monod, and logarithmic kinetics, respectively. Parameters such as maximum specific growth rate, half-saturation constant, and initial population density divided by yield agreed between cultures to within a factor of 3.4. Benzoate mineralization by microorganisms in acclimated sewage was shown to fit logistic (sigmoidal), Monod, and logarithmic kinetics when the compound was added at initial concentrations of 0.1, 1.0, and 10 micrograms/ml, respectively. The mineralization of 10 micrograms of benzoate per ml in sewage also followed logarithmic kinetics in the absence of protozoa. It is concluded that much of the diversity in shapes of mineralization curves is a result of the interactions of substrate concentration and population density. Nonlinear regression with models incorporating these variables is a valuable means for analysis of microbial mineralization kinetics.     

Overview of some theoretical approaches for derivation of the Monod equation

The Monod equation has been widely applied to describe microbial growth, but it has no mechanistic basis and is purely empirical. Extensive efforts have been dedicated to develop theoretical approaches for derivation of the Monod equation, which can be classified into three major groups, i.e., kinetic, thermodynamic, and substance transport approaches. In this review, four representative approaches are thus discussed. Due to the fact that different assumptions are made in each approach, no universal physical meaning of the Monod constant (K (s)) can be revealed. However, it seems that the Monod constant would be free energy-dependent and have nonequilibrium thermodynamic characteristics.     

Modeling of biofilm reactors with consecutive reactions

Modeling of biofilm reactors has been carried out by several authors. Most of the models use first-order or zero-order kinetics, because of the simplicity of the solution of the mathematical problem. However, the reaction kinetics for many practical situations is a non-linear Monod kinetics, which requires numerical solutions. This paper deals with the modeling of biofilm reactors and effectiveness factor calculations for a biofilm particle with Monod kinetics and two consecutive reactions. The model is applied to biological denitrification in a fluidized bed bioreactor, in which the liquid phase is assumed to be in plug flow. Effectiveness factors of biofilm are numerically calculated by solving the system of ODES by orthogonal collocation. Axial concentration profiles of nitrate and nitrite species are calculated and compared with experimental results.     

Resistance to chlorine of freshwater bacterial strains

The disinfectant properties of chlorine have been known for centuries but in the last few years water chlorination has attracted some criticism due to its secondary effects and the increased resistance of bacterial strains to chlorine inactivation. In this paper the kinetics of inactivation by chlorine of different Gram-positive and Gram-negative bacterial strains isolated from chlorinated water is studied. The Gram-positive strains were more resistant to chlorine and the behaviour of some of them in the presence of chloramphenicol suggests either the synthesis of unique proteins or aggregation of the bacteria as mechanisms of resistance to inactivation. The concept of K _i, the inactivation rate constant, by comparison with K _s in Michaelis-Menten enzyme kinetics (considering enzymic saturation), or with K _s in Monod growth kinetics (considering limiting rates of transport and metabolism of substrates), may be an interesting parameter to define microbial resistance to disinfectants and toxics.     

Kinetic modelling of organic matter removal in 80 horizontal flow reed beds for domestic sewage treatment

This paper reports a comparative study of four kinetic models that can be applied in the design of subsurface horizontal flow reed beds for wastewater treatment. The models were developed from different combinations of Monod kinetics, first-order kinetics, continuous stirred-tank reactor and plug flow patterns. Using three statistical parameters (coefficient of determination, relative root mean square error, and model efficiency), critical examinations were made on the accuracy of these models. For predicting organic matter removal, the combination of Monod kinetics with plug flow pattern gave the closest match between theoretical predictions and actual performances of 80 horizontal flow reed beds. In all four models, the coefficients of BOD removal were found to increase slightly with BOD loading. The ratios of BOD/COD had no correlation with the coefficients, indicating that in the horizontal flow reed beds the degradation of organic matter is insensitive to the nature of organics in the wastewater.     

Extended monod kinetics for substrate, product, and cell inhibition

A generalized form of Monod kinetics is proposed to account for all kinds of product, cell, and substrate inhibition. This model assumes that there exists a critical inhibitor concentration above which cells cannot grow, and that the constants of the Monod equation are functions of this limiting inhibitor concentration. Methods for evaluating the constants of this rate form are presented. Finally the proposed kinetic form is compared with the available data in the literature, which unfortunately is very sparse. In all cases, this equation form fitted the data very well.