Ahn I S, Ghiorse W C, Lion L W, Shuler M L
School of Chemical Engineering, Cornell University, Ithaca, New York 14853, USA.
Biotechnol Bioeng. 1998 Sep 5;59(5):587-94.
The objectives of this work were (1) to demonstrate how the chemostat approach could be modified to allow determination of kinetic parameters for a sparingly soluble, volatile substrate such as naphthalene and (2) to examine the influence of the interactions of various nutrients on possible growth-inhibitory effects of naphthalene. Pseudomonas putida G7 was used as a model naphthalene-degrading microorganism. Naphthalene was found to be toxic to P. putida G7 in the absence of a nitrogen source or oxygen. The death rate of cells grown on minimal medium plus naphthalene and then exposed to naphthalene under anoxic conditions was higher than that observed under oxic conditions in the absence of a nitrogen source. The presence of necessary nutrients for the biodegradation of PAH compounds is indicated to be important for the survival of microorganisms that are capable of PAH degradation. The amounts of ammonia and oxygen necessary for naphthalene biodegradation and for suppression of naphthalene toxicity were calculated from growth yield coefficients. A chemostat culture of P. putida G7 using naphthalene as a carbon and energy source was accomplished by using a feed augmented with a methanol solution of naphthalene so as to provide sufficient growth to allow accurate evaluation of kinetic parameters. When naphthalene was the growth-limiting substrate, the degradation of naphthalene followed Monod kinetics. Maximum specific growth rate (micrometer) and Monod constant (Ks) were 0.627 +/- 0.007 h-1 and 0.234 +/- 0.0185 mg/L, respectively. The evaluation of biodegradation parameters will allow a mathematical model to be applied to predict the long-term behavior of PAH compounds in soil when combined with PAH transport parameters.
（1）证明如何修改恒化器方法，以确定难溶性挥发性底物（如萘）的动力学参数；（2）研究各种养分相互作用对萘可能产生的生长抑制作用的影响。恶臭假单胞菌G7被用作萘降解微生物的模型。研究发现，在没有氮源或氧气的情况下，萘对恶臭假单胞菌G7有毒。在缺氧条件下，在基本培养基上加萘培养，然后暴露于萘中的细胞死亡率高于在无氮源的有氧条件下观察到的死亡率。多环芳烃化合物生物降解所需的必需养分的存在对能够降解多环芳烃的微生物的存活至关重要。根据生长产率系数计算出萘生物降解和抑制萘毒性所需的氨和氧气量。通过使用添加了萘甲醇溶液的进料来完成以萘为碳源和能源的恶臭假单胞菌G7的恒化器培养，从而提供足够的生长以准确评估动力学参数。当萘是生长限制底物时，萘的降解遵循莫诺德动力学。最大比生长速率（μm）和莫诺德常数（Ks）分别为0.627±0.007 h-1和0.234±0.0185 mg/L。生物降解参数的评估将使数学模型在与多环芳烃传输参数结合时能够用于预测多环芳烃化合物在土壤中的长期行为。
