Date on Master's Thesis/Doctoral Dissertation

8-2015

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Remold, Susanna

Committee Co-Chair (if applicable)

Carreiro, Margaret

Committee Member

Carreiro, Margaret

Committee Member

Emery, Sarah

Committee Member

Moore, Francisco

Committee Member

Perlin, Michael

Subject

Pseudomonas; Bacteria--Ecology

Abstract

Resources influence the distribution, behavior, growth and reproduction of bacterial species. Understanding how closely related species utilize resources will shed light on the ecological traits or principles that shape biogeographic patterns and promote coexistence of species. Twelve Pseudomonas strains isolated from a single human home and PA01, the standard laboratory strain were evaluated in Luria Bertani media to understand whether their growth traits are influenced by their species group and/or their environment of isolation. Total growth, growth rate, early cumulative area under the growth curve (CUC) over 48 hours and viability (viable bacteria count per ml) at 24 and 48 hours were evaluated for each strain. I found differences in growth strategies that may be driven by species group and/or environment of isolation. These results suggest local adaptation of Pseudomonas strains to human home environments. These strains were also evaluated for their metabolic and oxidative profiles in 31 resources as a way to understand if metabolic and/or oxidative profiles could be predicted by their species group and/or their environment of isolation. Metabolic profile for each strain was evaluated as the qualitative ability to use a resource coded as 0 or 1, while the oxidative profile in each resource is a quantitative measure that was determined by integrating the CUC for each resource after 48 hours of growth. I found some resources were utilized by all the strains, suggesting similar metabolic adaptations or common ancestry. I also found evidence for resource differentiation that was driven by species group, but very little evidence for environment of isolation or local adaptation. Thus, resource differentiation can reduce competition and promote coexistence of species. Seventy five strains of Pseudomonas species group isolated from multiple human homes were also evaluated in 11 different resources to understand the effect of environment of isolation on their growth profiles. I found extensive variability in their growth profiles and detected no association between environment of isolation and resource use profiles, although there was a significant difference with reference to environments of isolation in the growth rate of the strains in L-glutamic acid resource. Such variations in phenotypic traits can increase fitness, reduce intraspecific competition, and help with the ability to respond to environmental change.

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