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Environmental Microbiology and Microbial Ecology

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2013

Bacteria

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Genetic And Ecological Characterization Of Indigoidine Production By Phaeobacter Sp. Strain Y4i, William Nathan Cude Aug 2013

Genetic And Ecological Characterization Of Indigoidine Production By Phaeobacter Sp. Strain Y4i, William Nathan Cude

Doctoral Dissertations

The Roseobacter clade is a widely distributed, abundant, and biogeochemically active lineage of marine alpha-proteobacteria. Members of the Roseobacter lineage are prolific surface colonizers in marine coastal environments, and antimicrobial secondary metabolite production has been hypothesized to provide a competitive advantage in colonization. In this work, Phaeobacter sp. strain Y4I was found to produce the water soluble, blue pigment indigoidine via a nonribosomal peptide synthase-based biosynthetic pathway encoded by a novel series of genetically linked genes, termed igiBCDFE. Comparison of wildtype, non-pigmented, and hyper-pigmented Y4I insertional mutants demonstrated a perfect correlation between indigoidine production and the inhibition of Vibrio …


Validating Approaches For Studying Microbial Diversity To Characterize Communities From Roots Of Populus Deltoides, Migun Shakya Aug 2013

Validating Approaches For Studying Microbial Diversity To Characterize Communities From Roots Of Populus Deltoides, Migun Shakya

Doctoral Dissertations

Microbial (archaeal, bacterial, and fungal) communities associated with plant roots are central to its health, survival, and growth. However, a robust understanding of root microbiota and the factors that govern their community structure and dynamics have remained elusive, especially in mature perennial plants from natural settings. Although the advent of Next Generation Sequencing (NGS) technologies have changed the scale of microbial ecological studies by enabling exhaustive characterization of microbial communities, the accuracy of taxonomic and quantitative inferences are affected by multiple experimental and computational steps and lack of knowledge of the true ecological diversity. To test for inaccuracies and biases, …


Revealing The Ecological Role Of Gemmatimonadetes Through Cultivation And Molecular Analysis Of Agricultural Soils, Mariam Naomi Fawaz May 2013

Revealing The Ecological Role Of Gemmatimonadetes Through Cultivation And Molecular Analysis Of Agricultural Soils, Mariam Naomi Fawaz

Masters Theses

Bacteria belonging to phylum Gemmatimonadetes are frequently detected in a variety of environments using culture-independent methods. Despite their ubiquity and prevalence, almost nothing is known about their physiology or ecology because so few strains have been isolated. The first objective of this study was to determine the distribution of Gemmatimonadetes within soil aggregates and the response of the relative abundance of Gemmatimonadetes to dry/wet cycling and soil management. The second objective was to analyze the effects of soil management, aggregate size, and atmospheric conditions on cultivability of Gemmatimonadetes. Universal and Gemmatimonadetes-specific 16S rRNA gene primers were used to …


Bacterial Community Profiling Of The Eastern Oyster (Crassostrea Virginica): Comparison Of Culture-Dependent And Culture-Independent Outcomes, Kenneth J. La Valley, Steve Jones, Marta Gomez-Chiarri, Joseph Dealteris, Michael A. Rice Apr 2013

Bacterial Community Profiling Of The Eastern Oyster (Crassostrea Virginica): Comparison Of Culture-Dependent And Culture-Independent Outcomes, Kenneth J. La Valley, Steve Jones, Marta Gomez-Chiarri, Joseph Dealteris, Michael A. Rice

Michael A Rice

Tissue-associated bacterial community profiles generated using a nested polymerase chain reaction–denaturing gradient gel electrophoresis (DGGE) approach and culture-dependent and culture-independent isolation techniques were compared. Oyster samples were collected from 2 harvest areas along the coast of Maine, in the United States. Profiles from both isolation strategies were evaluated using Sorensen’s index of similarity and cluster analysis of gel banding patterns. Cultureindependent profiles were further evaluated using the Shannon diversity index. In general, the culture-dependent strategy resulted in a greater number of bands within a profile. BacterialDGGEprofiles were found to be highly similar within an isolation strategy, with a higher degree …