Smith L H, Kitanidis P K, McCarty P L
Department of Process and Environmental Technology, Massey University, Palmerston North, New Zealand.
Biotechnol Bioeng. 1997 Feb 5;53(3):320-31. doi: 10.1002/(SICI)1097-0290(19970205)53:3<320::AID-BIT11>3.0.CO;2-O.
The rates of methane utilization and trichloroethylene (TCE) cometabolism by a methanotrophic mixed culture were characterized in batch and pseudo-steady-state studies. Procedures for determination of the rate coefficients and their uncertainties by fitting a numerical model to experimental data are described. The model consisted of a system of differential equations for the rates of Monod kinetics, cell growth on methane and inactivation due to TCE transformation product toxicity, gas/liquid mass transfer of methane and TCE, and the rate of passive losses of TCE. The maximum specific rate of methane utilization (k(CH(4) )) was determined by fitting the numerical model to batch experimental data, with the initial concentration of active methane-oxidizing cells (X(0) (a)) also used as a model fitting parameter. The best estimate of k(CH(4) ) was 2.2 g CH(4)/g cells-d with excess copper available, with a single-parameter 95% confidence interval of 2.0-2.4 mg/mg-d. The joint 95% confidence region for k(CH(4) ) and X(0) (a) is presented graphically. The half-velocity coefficient (K(S,CH(4) )) was 0.07 mg CH(4)/L with excess copper available and 0.47 mg CH(4)/L under copper limitation, with 95% confidence intervals of 0.02-0.11 and 0.35-0.59 mg/L, respectively. Unique values of the TCE rate coefficients k(TCE) and K(S,TCE) could not be determined because they were found to be highly correlated in the model fitting analysis. However, the ratio k(TCE)/K(S,TCE) and the TCE transformation capacity (T(C)) were well defined, with values of 0.35 L/mg-day and 0.21 g TCE/g active cells, respectively, for cells transforming TCE in the absence of methane or supplemental formate. The single-parameter 95% confidence intervals for k(TCE)/K(S,TCE) and T(C) were 0.27-0.43 L/mg-d and 0.18-0.24 g TCE/g active cells, respectively. The joint 95% confidence regions for k(TCE)/K(S,TCE) and T(C) are presented graphically.
在分批培养和准稳态研究中，对甲烷营养混合培养物利用甲烷和三氯乙烯（TCE）共代谢的速率进行了表征。描述了通过将数值模型拟合到实验数据来确定速率系数及其不确定性的程序。该模型由一组微分方程组成，分别描述了莫诺德动力学速率、细胞利用甲烷生长以及因TCE转化产物毒性导致的失活、甲烷和TCE的气/液传质以及TCE的被动损失速率。通过将数值模型拟合到分批实验数据来确定甲烷利用的最大比速率（k(CH(4))），同时将活性甲烷氧化细胞的初始浓度（X(0)(a)）也用作模型拟合参数。在有过量铜存在的情况下，k(CH(4))的最佳估计值为2.2 g CH(4)/g细胞·天，单参数95%置信区间为2.0 - 2.4 mg/mg·天。以图形形式给出了k(CH(4))和X(0)(a)的联合95%置信区域。在有过量铜存在时，半速度系数（K(S,CH(4))）为0.07 mg CH(4)/L，在铜限制条件下为0.47 mg CH(4)/L，95%置信区间分别为0.02 - 0.11和0.35 - 0.59 mg/L。由于在模型拟合分析中发现TCE速率系数k(TCE)和K(S,TCE)高度相关，无法确定其唯一值。然而，k(TCE)/K(S,TCE)的比值和TCE转化能力（T(C)）定义明确，对于在无甲烷或补充甲酸盐情况下转化TCE的细胞，其值分别为0.35 L/mg·天和0.21 g TCE/g活性细胞。k(TCE)/K(S,TCE)和T(C)的单参数95%置信区间分别为0.27 - 0.43 L/mg·天和0.18 - 0.24 g TCE/g活性细胞。以图形形式给出了k(TCE)/K(S,TCE)和T(C)的联合95%置信区域。
