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首页> 外文学位 >Characterizing MTBE cometabolism and propane metabolism by Mycobacterium austroafricanum JOB5.
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Characterizing MTBE cometabolism and propane metabolism by Mycobacterium austroafricanum JOB5.

机译：通过奥氏分支杆菌JOB5表征MTBE代谢和丙烷代谢。

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摘要

Cometabolic transformations are unable to support cell growth. This process is often catalyzed by, and superimposed upon, enzyme systems expressed to catalyze carbon- or energy-yielding reactions. Biodegradation of the gasoline additive methyl tertiary butyl ether (MTBE) is known to be superimposed upon a propane-oxidizing system in the aerobic bacterium Mycobacterium austroafricanum (previously vaccae) JOB5. Taking a whole-cell approach, we investigated the physiology of propane metabolism and MTBE cometabolism in this strain.;Multiple major gasoline components are frequent co-contaminants with MTBE in the environment, and we determined the impacts of these hydrocarbons on the cometabolism of both MTBE and its commonly encountered metabolite, tertiary butyl alcohol (TBA). Most of the hydrocarbons tested supported cell growth and concurrent MTBE and TBA oxidation occurred without affecting final culture optical density. Hydrocarbon-grown cells seem to simultaneously express more than one alkane-oxidizing enzyme system.;Nuclear magnetic resonance spectroscopy (NMR) was used to study the pathway of MTBE oxidation in propane-grown cells. We confirmed the existence of predicted intermediates, including a hemiacetal, formate and formaldehyde. Hydroxyisobutyraldehyde, a predicted intermediate in MTBE oxidation by some bacterial strains was not detected, despite attempts to promote its accumulation. As the pathway of MTBE oxidation progressed, the rate of daughter product oxidation decreased, which may be preventing MTBE-dependent cell growth in strain JOB5.;Propane metabolism was examined using a series of growth experiments and substrate oxidation assays. We observed the simultaneous production, and later consumption of both 1- and 2-propanol during cell growth. This divergent oxidation of propane was apparently followed by the divergent oxidation of propionate and the divergent oxidation of acetone. Our results suggest at least two CO2-fixation steps are involved in propane metabolism in strain JOB5.;Finally, we used NMR to contribute to several studies that characterized the pathway of (i) MTBE oxidation by Nitrosomonas europaea or (ii) bacterial oxidation of a fluorinated analog of TBA. The later study identified a compound that may serve as a tracer for TBA degradation in situ.
机译：代谢转换无法支持细胞生长。该过程通常由表达成催化产生碳或能量的反应的酶体系催化并叠加。已知汽油添加剂甲基叔丁基醚（MTBE）的生物降解被叠加在好氧细菌南非分枝杆菌（以前的牛痘）JOB5中的丙烷氧化系统上。我们采用全细胞方法研究了该菌株中丙烷代谢和MTBE代谢的生理学;;多种主要汽油成分是环境中与MTBE常见的共同污染物，我们确定了这些碳氢化合物对二者的代谢作用的影响MTBE及其常见的代谢物叔丁醇（TBA）。测试的大多数碳氢化合物支持细胞生长，同时发生MTBE和TBA氧化，而不影响最终培养物的光密度。碳氢化合物生长的细胞似乎同时表达一种以上的烷烃氧化酶系统。核磁共振波谱（NMR）用于研究丙烷生长的细胞中MTBE氧化的途径。我们确认存在预测的中间体，包括半缩醛，甲酸和甲醛。尽管试图提高羟基异丁醛的含量，但仍未检测到某些细菌菌株在MTBE氧化中的预测中间体。随着MTBE氧化途径的发展，子产物氧化速率降低，这可能阻止了菌株JOB5中MTBE依赖性细胞的生长。通过一系列的生长实验和底物氧化实验研究了丙烷的代谢。我们观察到在细胞生长过程中同时产生1-丙醇和2-丙醇，并随后消耗。丙烷的发散氧化显然之后是丙酸酯的发散氧化和丙酮的发散氧化。我们的结果表明，菌株JOB5的丙烷代谢至少涉及两个CO2固定步骤;最后，我们使用NMR进行了几项研究，这些研究表征了（i）欧洲硝化单胞菌MTBE氧化或（ii）细菌氧化的MTBE途径。 TBA的氟化类似物。后来的研究确定了一种化合物，可作为原位TBA降解的示踪剂。

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  • 作者

    House, Alan Jay.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Biology Microbiology.;Environmental Sciences.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 231 p.
  • 总页数 231
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 微生物学;环境科学基础理论;
  • 关键词

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