Dissertation/Thesis Abstract

Comparative microbial ecology of sediment-associated microbial communities from anthropogenically and endogenously metal impacted systems
by Sackett, Joshua David, M.S., University of Colorado at Denver, 2015, 140; 1598320
Abstract (Summary)

Microorganisms, particularly the Bacteria, are differentially impacted by metal toxicities, and will respond very quickly to changes in their environment, making them ideal bioindicators of environmental health. In this study, we evaluated the sediment-associated bacterial diversity of fifty-seven samples collected from twenty-four anthropogenically and endogenously metal impacted, geographically distinct sites in the Colorado Mineral Belt, and elucidated the factors that correlated with observed differences in the bacterial community structure. Overall, the geochemistry of all sites distinguished anthropogenic from endogenous sources of metal impact. Anthropogenic samples, on average, had higher concentrations of total recoverable and dissolved sodium and magnesium, and lower concentrations of aluminum and zinc, compared to the endogenous samples. Bacterial communities from both anthropogenically and endogenously metal impacted sites were characterized using Illumina high-throughput amplicon sequencing of the V4 region of the 16S rRNA gene. Overall, bacterial communities were remarkably diverse, with endogenously metal impacted sediments having higher diversity compared to anthropogenic sediments. The Actinobacteria and Betaproteobacteria dominated anthropogenic samples, and the Acidobacteria and Deltaproteobacteria dominated endogenous samples. Clustering of bacterial communities based on membership and structure (presence/absence and relative abundance of particular taxa, respectively) also distinguished samples based on their source of metal impact. Analysis of similarity (ANOSIM) tests indicated a significant difference between bacterial community structure based on source of metal impact (weighted UniFrac RANOSIM = 0.746, p = 0.001). Mantel tests indicated that total recoverable magnesium concentrations accounted for ∼54% of variance in community structure of all bacterial communities in the study. Dissolved aluminum concentrations accounted for ∼71% of the variation in all communities with an anthropogenic source of metal, and dissolved aluminum concentrations also accounted for ∼41% of the variation in bacterial communities with endogenous sources of metal impact.

This study provides one of the first direct comparisons between microbial community structures of sediments based on source of metal impact. This study is also one of the first comprehensive characterizations of bacterial communities from naturally occurring iron fen systems.

Indexing (document details)
Advisor: Roane, Timberley M.
Commitee: Miller, Christopher S., Wunder, Michael
School: University of Colorado at Denver
Department: Biology
School Location: United States -- Colorado
Source: MAI 55/01M(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Microbiology, Environmental science
Keywords: 16S rRNA, Acid mine drainage, Acid rock drainage, Bacterial community structure, Iron fen, Next-generation sequencing
Publication Number: 1598320
ISBN: 9781339027883
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