Effects of oxygen and nitrogen conditions on the transformation kinetics of 1,2-dichloroethenes by Methylosinus trichosporium OB3b and its sMMOC mutant
Effects of oxygen and nitrogen conditions on the transformation kinetics of 1,2-dichloroethenes by Methylosinus trichosporium OB3b and its sMMOC mutant
复制标题
氧氮条件对毛孢甲基窦菌OB3b及其sMMOC突变体转化1,2-二氯乙烯动力学的影响
作者：
H. J. Kim;D. Graham
测定了毛孢甲基窦菌 OB3b 野生型 (WT) 和 PP319 的反式和顺式二氯乙烯 (DCE) 转化动力学，以评估 O2 水平和 N2 固定对降解能力的影响。研究了两个问题：(1) 氧气水平和氮限制对两种生物体中 DCE 降解动力学和毒性的影响，以及 (2) PP319 在生物反应器中降解污染物的相对效用。当两种生物体在高 O2 条件（空气中 80% 饱和度）下生长时，无论氮水平如何，与低 O2 条件（空气中 10% 饱和度）下生长的生物体相比，最大转化率 (Vmax) 和表观一级速率常数 (Vmax/KM) 较低。此外，当 O2 较高时（如预期），在氮限制的 WT 培养物中，Vmax 值接近于零，而 PP319 即使在高 O2 水平下也保留中等 Vmax 水平。一般来说，升高的 O2 条件降低了 OB3b 中的 DCE 降解率，尽管 O2 在 PP319 中的负面影响比在 WT 中要小。鉴于 PP319 在大多数 O2 和铜条件下保留了中等的 DCE 降解率，该突变体似乎对生物降解应用具有一定的实用性。
Transformation kinetics of trans- andcis-dichloroethylenes (DCE) by Methylosinus trichosporium OB3b wild type (WT)and PP319, a mutant that expresses soluble methane monooxygenase at copper levels upto ∼12 μM Cu (sMMOC), were determined to assess theeffects of O2level and N2-fixation on degradationcapabilities. Two issues were examined: (1) the influence of O2level and nitrogen-limitation on DCE degradationkinetics and toxicity in both organisms, and (2) the relative utility of PP319 forcontaminant degradation in bioreactors. When both organisms were grown underhigh O2conditions (80% saturation in air), maximum transformation rates(Vmax) and apparent first-order rate constants(Vmax/KM) were lower compared with organisms grown under low O2conditions (10% saturation in air)regardless of nitrogen level. Further, Vmax values were near zero innitrogen-limited WT cultures when O2was high (as expected), whereas PP319 retainedmoderate Vmax levels even at high O2levels. In general, elevatedO2conditions reduced DCE degradation rates in OB3b, although the negative effectsof O2were less in PP319 than in the WT. Given that PP319 retained moderate DCEdegradation rates under most O2and copper conditions, the mutant appears to havesome utility for biodegradation applications.
影响因子：
2.9
作者：
FOX, BG;BORNEMAN, JG;LIPSCOMB, JD
通讯作者：
LIPSCOMB, JD