Dissertation Research: Assessing Humic Inhibition of Microbial Processes in Aquatic Systems

9623323 Sinsabaugh评估水生系统中微生物过程的腐殖酸抑制。 溶解有机碳长期以来被认为是许多水生生态系统的主要能量来源。然而，在大多数系统中，DOC是由不稳定和不稳定物质的非均相混合物组成的，其特征还不是很清楚。以前的研究表明，DOC池的相当大的一部分是由高分子量的腐殖酸/酚类化合物，是耐火的性质。这些物质中的一些可以被微生物直接利用，而另一些可能需要酶处理才能被同化。这些酚类化合物的存在可能对DOC的处理有重要影响。本研究的目的是调查DOC质量和微生物群落的性质之间的关系。初步研究表明，DOC池的某些组分，即酚类化合物，可以起到刺激和抑制细菌生产力的作用。通过一系列单独的实验，可能会阐明这种关系背后的一些潜在机制。PI建议检查可能与细菌生产力相关的几个参数，包括胞外酶活性、质粒筛选和基本DOC表征。这些试验将在微观和田间试验中进行。

9623323 Sinsabaugh Assessing humic inhibition of microbial processes in aquatic systems. Dissolved organic carbon has long been recognized as being a major source of energy in many aquatic ecosystems. However, in most systems the DOC is composed of a heterogeneous mixture of both labile and recalcitrant substances which have not been very well characterized. Previous studies have indicated that a sizable portion of the DOC pool is composed of high molecular weight humic/phenolic compounds that are refractory in nature. Some of these substances may be utilized directly by microorganisms, while others may require enzymatic processing before they can be assimilated. The presence of these phenolic compounds may have an important influence on the processing of DOC. The objective of this study is to investigate the relationship between DOC quality and the nature of the microbial community. Preliminary work has shown that certain fractions of the DOC pool, namely phenolic compounds, can act to both stimulate and inhibit bacterial productivity. Through a series of individual experiments it may be possible to elucidate some of the underlying mechanisms behind this relationship. The PIs propose to examine several parameters which may be linked with bacterial productivity, including extracellular enzyme activities, plasmid screenings, and elementary DOC characterization. These assays will be conducted in both microcosm and field trials.