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首页> 外文学位 >Phenanthrene and hexadecane biodegradation and degrader community dynamics in rhizosphere soil: Mechanisms responsible for enhancement.
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Phenanthrene and hexadecane biodegradation and degrader community dynamics in rhizosphere soil: Mechanisms responsible for enhancement.

机译：根际土壤中菲和十六烷的生物降解和降解物的群落动力学：增强机理。

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摘要

While many studies to date have demonstrated that plant-enhanced bioremediation in petroleum-contaminated soils is a promising and cost-effective soil remediation alternative, the mechanisms responsible for rhizoremediation have yet to be experimentally elucidated. The objectives of my dissertation work were [1] to determine if a predictable link between plant-enhanced phenanthrene biodegradation and degrader community dynamics in Avena barbata (slender oat) rhizosphere soil could be established, [2] to define the role(s) of individual slender oat rhizosphere components in accelerated phenanthrene biodegradation, and [3] to investigate contaminant specificity by comparing phenanthrene and hexadecane biodegradation and degrader community dynamics in slender oat rhizosphere soil.; Enhanced phenanthrene biodegradation rates were observed in soils planted with slender oat compared to unplanted bulk soil. Quantitative estimates of heterotrophic and phenanthrene degrader populations indicated that enrichment of degraders occurred during the mature stages of plant growth, primarily due to the maintenance of significantly larger degrader populations in rhizosphere soils. Data obtained from phenanthrene degrader isolates also indicated that the rhizosphere degraders were less diverse than bulk soil degraders. The rhizosphere was a more hospitable environment for phenanthrene degraders compared to bulk soil. Hydroponically collected slender oat root exudates had the largest individual impact on phenanthrene biodegradation enhancement and a combined root exudate + root debris-amended soil had the most rapid phenanthrene biodegradation rate. Root exudate-amended soils also supported the largest degrader populations compared to root amended and unamended soils. Hexadecane-contaminated rhizosphere soil did not support accelerated biodegradation rates compared to bulk soil indicating that slender oat-enhanced bioremediation is contaminant specific. Despite the absence of enhanced biodegradation, hexadecane degrader populations were selectively maintained in rhizosphere soils compared to bulk soils. No specific rhizosphere impact on microbial degraders in contaminated soils adequately explained the observed differences in biodegradation rate enhancement in phenanthrene versus hexadecane contaminated soils.; Each objective of my dissertation research was successfully accomplished. My results indicate that [1] plant-enhanced phenanthrene biodegradation enhancement in slender oat rhizosphere soil was carried out by a quantitatively larger and less diverse microbial community of degraders, [2] slender oat root exudates enhanced phenanthrene biodegradation rates by stimulating degrader populations, and [3] plant-enhanced petroleum biodegradation was contaminant-specific as hexadecane biodegradation was not accelerated in slender oat rhizosphere soil.
机译：尽管迄今为止的许多研究表明，在石油污染的土壤中进行植物增强的生物修复是一种有前途且具有成本效益的土壤修复替代方法，但用于根茎修复的机理尚未通过实验阐明。我的论文工作的目标是[1]确定是否可以建立植物增强的菲生物降解与 barvena （细长燕麦）根际土壤中降解体群落动态之间的可预测联系，[2]定义单个细长燕麦根际层成分在加速菲生物降解中的作用，并[3]通过比较细长燕麦根际土壤中菲和十六烷的生物降解以及降解物群落动态来研究污染物的特异性。与未种植的散装土壤相比，在修长的燕麦种植的土壤中观察到了菲生物降解速率的提高。异养和菲降解菌种群的定量估计表明，降解菌的富集发生在植物生长的成熟阶段，这主要是由于在根际土壤中维持了较大的降解菌种群。从菲降解物分离物获得的数据还表明，根际降解物的多样性不如散装土壤降解物。与大量土壤相比，根际对菲降解物而言是一个更友好的环境。水培法收集的细长燕麦根系分泌物对菲生物降解的促进作用最大，根系分泌物+根碎屑联合处理的土壤对菲的生物降解速度最快。与根部改良和未改良的土壤相比，根系分泌物改良的土壤也支持最大的降解菌种群。与散装土壤相比，被十六烷污染的根际土壤不支持加速的生物降解速度，这表明细长的燕麦强化生物修复具有污染物特异性。尽管缺乏增强的生物降解能力，但与块状土壤相比，在根际土壤中十六烷降解剂的种群仍被选择性地维持。没有具体的根际对受污染土壤中微生物降解菌的影响充分解释了在菲和十六烷污染土壤中观察到的生物降解速率提高的差异。我论文研究的每个目标都成功实现了。我的结果表明，[1]细长燕麦根际土壤中植物的菲生物降解增强是通过数量较大且多样性较低的降解菌微生物群落来实现的，[2]细长燕麦根系分泌物通过刺激降解菌种群提高了菲生物降解速率，并且[3]植物强化的石油生物降解是污染物特异性的，因为在细长的燕麦根际土壤中十六烷的生物降解没有被加速。

著录项

  • 作者

    Miya, Ryan Kirk.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Agriculture Soil Science.; Environmental Sciences.; Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 125 p.
  • 总页数 125
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 土壤学;环境科学基础理论;微生物学;
  • 关键词

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