Environmental Microbiology and Microbial Ecology Commons^™

Exploring The Durability Of Marine Picocyanobacterial Microcolonies, Erik Swanson

University Honors Theses

Picocyanobacteria of the genus Synechococcus are widespread aquatic photoautotrophs that play essential roles in primary production and carbon cycling. Some Synechococcus strains form multicellular microcolonies, but the mechanisms of cell-to-cell attachments and structural durability of these microcolonies remain poorly understood. This research investigated the physical durability of microcolonies in two marine Synechococcus strains (CC9605 and CC9311) using physical disruption treatments. Cultures were subjected to vortexing and sonication treatments, and populations of single cells and microcolonies were quantified using flow cytometry based on differences in measures of size. Results indicated that strain CC9605 showed no significant treatment effect, whereas CC9311 displayed …

Biofilm Architecture Determines Proliferation Of Phages And Plasmids, James B. Winans

Dartmouth College Ph.D Dissertations

This thesis explores how biofilm architecture determines the spread and ecological consequences for the bacteria-dependent genetic elements phages and plasmids. Using Escherichia coli and Vibrio cholerae as model microbes, and the genetic elements T7 phages, λ phages, and conjugative plasmid pED208, we investigate how spatial structure influences phage infection dynamics, plasmid transfer, and interbacterial interactions within biofilms. We show that densely packed biofilms can protect sensitive bacteria from phage exposure and modulate competitive outcomes between obligately lytic and temperate phages. We find that entirely different outcomes can coöccur within microns of each other dependent on biofilm structure. We also demonstrate …

Unveiling The Bacterial Communities Of Aphaenogaster: Taxonomic Composition, Developmental And Species Influences, And The Impact Of Climate Change, Lily Kelleher

West Chester University Master’s Theses

Ants are vital keystone species in many ecosystems because they provide ecosystem services such as: seed dispersal, soil bioturbation, and pest control. However, ant bacterial symbioses remain largely unstudied, but these interactions are crucial because microbes play a vital role in the ants’ overall health. Today, global climate change is impacting our biodiversity, and we can use information about how changing temperatures impact the symbiotic bacterial communities associated with ants to predict future impact. Aphaenogaster rudis and A. fulva remain understudied in terms of their bacterial community and are important North American species. For this study, ants from several colonies …

Exploring The Dynamics Of Bacterial Populations In The Gut Microbiota, Shaikh Obaidullah

Biology and Medicine Through Mathematics Conference

No abstract provided.

The Effect Of Algal Wastewater Treatment Systems On Microbial Communities, Alexis Leach

University Honors Program Senior Projects

In collaboration with the Metropolitan Water Reclamation District of Greater Chicago and Gross-Wen Technologies, I examined the microbial communities in experimental tertiary wastewater treatment systems employing algal phytoremediation. Three algal phytoremediation systems were examined: two vertical conveyor belt systems, known as the 10-foot belt system and the series 4 system, and a third system lacking a converter belt in which planktonic algae grew in a control pond. I used EcoPlates to measure carbon substrate utilization by microorganisms in each system. EcoPlates contain thirty-one different carbon substrates, with a dye that indicates microbial use of each substrate. I conducted a Principal …

Occurrence Of Kanamycin-Resistant Bacteria Relative To Anthropogenic Pollution Along Richland Creek In Nashville, Tn​, Jolene Ho Mach, Annie Le, Brandon Torres Ramirez

Science University Research Symposium (SURS)

The overuse of antibiotics has caused an increase in antibiotic-resistant (AR) bacteria, which is a serious public health concern. Previous studies showed a significant correlation between anthropogenic pollution and AR bacteria. This project aims to identify AR bacteria in Richland Creek relative to local anthropogenic pollution. Water samples were collected at four locations along Richland Creek in Nashville, Tennessee. Bacteria resistant to the antibiotic kanamycin were isolated from the water samples, identified to genera using DNA barcoding, and compared among the sites. We expect to see a greater abundance and diversity of kanamycin-resistant bacteria closer to the end than near …

Consequences Of Biofilm Architecture On Vibrio Cholerae Ecology And Life History, Benjamin Ray Wucher

Dartmouth College Ph.D Dissertations

The diversity of microbes and the environments they inhabit are staggering. In many of these environments, bacteria have evolved to form sessile surface attached communities called biofilms. These biofilms have wide reaching impacts from importance in global carbon cycling, to persistent catheter infections, to biofouling and wastewater treatment. While many species of microbes form biofilms to survive in their environment, the architectures of these structures vary widely between organisms. Even though a great deal of work has been done to understand bacterial communities and their functions, little work has examined how the spatial aspects of biofilm architecture can affect the …

Effects Of Mass Death On Community Structure And Ecosystem Function, Abby Kimpton Jones

Theses and Dissertations

Death and decomposition are natural processes that are generally well-understood. However, large events of death, such as mass mortality events (MMEs) are increasing in frequency and their impacts on the ecosystem are largely unknown. These events may have both bottom-up effects from increased nutrient input as well as top-down effects from loss of an ecological functional group by the affected population. Different functional MMEs may result in different top-down effects, creating cascading effects. In Chapter 1, I test the hypothesis that scavenger and herbivore simulated MMEs generate novel bottom-up and top-down effects. Results indicate that MMEs have a significant effect …

Parameter Estimation Using Nudging On The Logistic Growth Equation, Susan Rogowski

Biology and Medicine Through Mathematics Conference

No abstract provided.

Analysis And Identification Of Lipolytic Bacterial Species For The Degradation Of Wastewater Lipids, Lindsay C. Smoak

Honors College Theses

The aim of this study was to isolate native bacterial strains from the wastewater treatment facilities of Statesboro, GA to identify their lipolytic activities. Obtained bacterial strains were further assessed via morphological and biochemical methods to determine their enzymatic capabilities. Use of the detergent Tween-20 in growth mediums was the first criteria to assess lipase activity, and these isolates were further investigated to quantitatively measure lipase presence and activity. Lipase protein was precipitated and dialyzed to perform a lipase activity assay, followed by Sodium Dodecyl Sulphate–Polyacrylamide Gel Electrophoresis (SDS-PAGE) to confirm the presence of the lipolytic enzymes. Sanger sequencing was …

Spotted Salamander Egg Masses Exhibit A Unique Internal Microbiome In Relation To Their Environment, Elizabeth Leonard

Senior Honors Theses

Microbial studies have led to various ecological and medicinal discoveries. Amphibian eggs, like those of Ambystoma maculatum, exhibit natural resistance to bacterial invasion that may be microbiome related. The purpose of this research was to sequence the external and internal microbiome of A. maculatum egg masses and compare with the environmental microbiome. It was hypothesized that the external and internal microbiome would bear more similarity to each other than the water. A significant difference was observed between the microbiome of the inside surface of the egg mass and the water but not the outside surface of the egg and …

Mathematical Modeling Of Gliding Motility And Its Regulation In Myxococcus Xanthus, Yirui Chen

Biology and Medicine Through Mathematics Conference

No abstract provided.

Diversity Analysis Of Soil Fungus Communities In Disturbed, Nursery, And Mature Forest Conditions, Dana Whitmore

All Master's Theses

Populations of soil fungi were examined in Derby Canyon Natives, Coeur d’Alene Forest Service nursery, Swamp Lake, and the Keechelus Lake wildlife overcrossing soils. All sampling sites were connected by their relation to the revegetation and native soil plug inoculation of the wildlife overpass. This study was an effort to describe soil fungi communities present on the overpass before plant introduction, those that plants would be bringing in their pots, and the fungi that could be introduced via soil plug transplantation. DNA was extracted from soil samples, then sequenced using next-generation sequencing methods, allowing for the analysis of species richness …

Glycolic Acid Utilization In Two Species Of Marine Bacteria, Erik S. Timsak

STAR Program Research Presentations

Interactions between bacteria and phytoplankton are crucial for the cycling of organic matter in marine environments. Around 50% of organic carbon taken up by marine bacteria is converted into inorganic carbon. The uptake of organic carbon by marine bacteria exuded from phytoplankton is a key factor in regulating the marine carbon cycle. One such molecule that is exuded by phytoplankton and then uptaken by marine bacteria is called glycolate - the anion of glycolic acid, a two caron molecule. Glycolate is exuded by phytoplankton during photorespiration and 10-50% of dissolved organic carbon in marine environments is comprised of glycolate. Additionally, …

Microbial Community Richness Distinguishes Shark Species Microbiomes In South Florida, Rachael Cassandra Karns

HCNSO Student Theses and Dissertations

The microbiome (microbial community) of individuals is crucial when characterizing and understanding processes that are required for organism function and survival. Microbial organisms, which make up an individual’s microbiome, can be linked to disease or function of the host organism. In humans, individuals differ substantially in their microbiome compositions in various areas of the body. The cause of much of the composition diversity is yet unexplained, however, it is speculated that habitat, diet, and early exposure to microbes could be altering the microbiomes of individuals (Human Microbiome Project Consortium, 2012b, 2012a). To date, only one study has reported on microbiome …

Ciliates Of Sagebrush-Steppe Soils Of Southwestern Idaho: Species Richness And Its Relationship To Changed Soil Variables After Wildfire Events, Laura G. Wendell

Boise State University Theses and Dissertations

I conducted a pilot study to examine species richness of terrestrial ciliates associated with big sagebrush habitat (Artemisia tridentata) in southwestern Idaho, USA. As wildland fires are a naturally occurring disturbance in this area, soil variables associated with these fires (% C, % N, pH, soil texture, and % clay) were measured at three sites, both in burned and unburned areas. These soil characteristics were compared to corresponding ciliate diversity and ratios of r-selected colpodeans to K-selected polyhymenophorans (C/P) in non-flooded Petri dish preparations. A total of 85 ciliate taxa were observed across the three sites, including …

Bacterial Community Structure Of Contrasting Soils Underlying Bornean Rain Forests: Inferences From Microarray And Next-Generation Sequencing Methods, Sabrina E. Russo, Ryan Legge, Karrie A. Weber, Eoin L. Brodie, Katherine C. Goldfarb, Andrew K. Benson, Sylvester Tan

School of Biological Sciences: Faculty Publications

Soil microbial diversity is vast, and we lack even basic understanding of how this diversity is distributed ecologically. Using pyrosequencing and microarray methods, we quantified the structure of bacterial communities in two contrasting soils underlying Bornean rain forest (clay and sandy loam) that differ markedly in soil properties, aboveground tree flora, and leaf litter decomposition rates. We found significant soil-related taxonomic and phylogenetic differences between communities that, due to their proximity, are independent of climate. Bacterial communities showed distinct compositional and taxon-abundance distributions that were significantly correlated with the structure of the overlying tree community. Richness of bacteria was greater …

Gravesoil Microbial Community Structure During Carcass Decomposition, Amy E. Maile

Department of Entomology: Dissertations, Theses, and Student Research

Dead bodies placed on soil represent unique challenges for investigators. Although processes in soils can be used to estimate postmortem interval, we know very little about how carcasses and insects affect gravesoil microbial communities.

To address this, the current project was composed of two experiments. Experiment one was conducted to investigate the effect of surface type on carcass decomposition and evaluate soil ecology methods. Experiment two was conducted to investigate the presence of an insect population (Lucilia sericata Meigen) on gravesoil microbial communities. Both experiments were conducted in a laboratory setting using freshly killed mouse carcasses. Mouse carcasses were …

Characterization Of Aerobic Respiration In Great Basin Hot Springs, Caitlin N. Murphy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Despite a wide diversity of possible electron donors available to fuel chemolithotrophy, it has been proposed that hydrogen is the single most important electron donor in geothermal ecosystems. To directly test this hypothesis, a simple system was devised to determine whether microorganisms in hot spring water and sediment are capable of using hydrogen and other electron donors for aerobic respiration using microrespirometry. The protocol for these experiments was developed using pure cultures of Thermocrinis ruber to determine the effect of growth conditions on the rate of oxygen consumption following the addition of electron donors. For field experiments, samples were collected …

Parasites Alter Community Structure, Chelsea L. Wood, James E. Byers, Kathryn L. Cottingham, Irit Altman

Dartmouth Scholarship

Parasites often play an important role in modifying the physiology and behavior of their hosts and may, consequently, mediate the influence hosts have on other components of an ecological community. Along the northern Atlantic coast of North America, the dominant herbivorous snail Littorina littorea structures rocky intertidal communities through strong grazing pressure and is frequently parasitized by the digenean trematode Cryptocotyle lingua. We hypothesized that the effects of parasitism on host physiology would induce behavioral changes in L. littorea, which in turn would modulate L. littorea's influence on intertidal community composition. Specifically, we hypothesized that C. lingua …