Microbiology Commons^™

Discovering Novel Polyextremotolerant Fungi, And Determining Their Ecological Role Within The Biological Soil Crust Consortium, Erin Carr

School of Biological Sciences: Dissertations, Theses, and Student Research

The ecological niche of polyextremotolerant fungi within oligotrophic ecosystems such as biological soil crusts has not yet been determined. These fungi persist in locations where nutrients are depleted while simultaneously surrounded by autotrophic microbes such as algae and cyanobacteria. Yet it has not been shown that they are engaging in any exchange of nutrients the way lichens do. However, there is seemingly no other way for these fungi to obtain vital nutrients, such as carbon or nitrogen, other than from these microbes. Here we have isolated polyextremotolerant fungi from cold desert biological soil crusts which are a microbial biofilm that …

A Cophylogenetic Analysis Of Fungus Gardening Ants And Their Symbiotic Fungi, Katherine Beigel

Biology Theses

Fungus-growing ants (Tribe Attini) and their fungal cultivars share a 50-million-year coevolutionary history. Large scale phylogenetic analyses depict a strong co-phyletic signal among ants and their farmed fungi yet fungus sharing among unrelated ant lineages is somewhat widespread. An overview of sharing has been hampered by a lack of genetic markers that exhibit intraspecific variation and surveys across geographic regions. For example, previous studies have shown similar sequences of the internal transcribed spacer (ITS) region of fungus in different species of Trachymyrmex, suggesting that these ant species are farming the same fungal clone. To examine whether this was a …

Spatio-Temporal Dynamics Of Fungal Communities And Their Effects On Plants, Kel Cook

Biology ETDs

Fungi perform several critical functions in the environment. Spatiotemporal distributions of fungal communities will mediate when and where these functions happen and how they vary across the landscape. I first explored tropical tree canopy fungal community variation at small spatial scales and documented near total turnover of fungi across sub-meter distances and among adjacent substrates. The second chapter analyzed fungal turnover over the course of three years, where community stability was driven primarily by abundant fungi. In the third chapter, I tested effects of the environment, including host plant and habitat, on canopy fungal communities and found only small effects, …

Investigation Of An Elevational Gradient Reveals Strong Differences Between Bacterial And Eukaryotic Communities Coinhabiting Nepenthes Phytotelmata, Kadeem J. Gilbert, Leonora S. Bittleston, Mark Arcebal K. Naive, Anthony E. Kiszewski, Perry Archival C. Buenavente, David J. Lohman, Naomi E. Pierce

Biology Faculty Publications and Presentations

Elevation is an important determinant of ecological community composition. It integrates several abiotic features and leads to strong, repeatable patterns of community structure, including changes in the abundance and richness of numerous taxa. However, the influence of elevational gradients on microbes is understudied relative to plants and animals. To compare the influence of elevation on multiple taxa simultaneously, we sampled phytotelm communities within a tropical pitcher plant (Nepenthes mindanaoensis) along a gradient from 400 to 1200 m a.s.l. We use a combination of metabarcoding and physical counts to assess diversity and richness of bacteria, micro-eukaryotes, and arthropods, and …

Investigation Of Origin And Growth Of Fungi In Coastal Beach Sand, Ruth L. Wright

Honors Theses

In a previous study from this lab (Stevens, Evans, & Aguirre, 2012) yeast colonies were isolated and grown grown from sand collection at pristine, medium use and high use beaches along the grand strand. In that study greater yeast abundance and greater diversity both correlated with higher census of human use, suggesting that some yeast growth of sites was anthropogenic. However the sand matrix itself also varied from very fine, uniform, dark sand at the pristine beach to coarser, color varying, less tightly packed sand at residential and commercial beaches. This suggested an alternative hypothesis to differential colonization and growth …

Diverse Microbial Communities Hosted By The Model Carnivorous Pitcher Plant Sarracenia Purpurea: Analysis Of Both Bacterial And Eukaryotic Composition Across Distinct Host Plant Populations, Jacob J. Grothjan, Erica B. Young

Biological Sciences Faculty Articles

Background. The pitcher plant Sarracenia purpurea supplements nutrient acquisition through carnivory, capturing insect prey which are digested by a food web community of eukaryotes and bacteria. While the food web invertebrates are well studied, and some recent studies have characterized bacteria, detailed genetic analysis of eukaryotic diversity is lacking. This study aimed to compare eukaryotic and bacterial composition and diversity of pitcher communities within and between populations of host plants in nearby but distinct wetland habitats, and to characterize microbial functions across populations and in comparison with another freshwater community.

Methods. Pitcher fluid was sampled from the two …

The Role And Contribution Of Saprotrophic Fungi During Standing Litter Decomposition Of Two Perennial Grass Species, Schizachyrium Scoparium And Schizachyrium Tenerum, Matthew Lodato

Master's Theses

In terrestrial ecosystems, most of the plant biomass produced enters the detrital pool, where microbial decomposers colonize, enzymatically degrade, and assimilate plant litter carbon and nutrients in amounts sufficient to bring about the decomposition of plant litter. Here, I estimated the biomass and production of fungi and microbial respiration associated with decaying Schizachyrium scoparium and Schizachyrium tenerum leaf litter, and constructed a partial organic matter budget estimating C flow into and through fungal decomposers. Significant losses in S. scoparium (57%) and S. tenerum (68%) leaf mass was observed during litter decomposition along with concomitant increases in fungal biomass, which reached …

Wood Decomposition In A Warmer World, Emily Elizabeth Austin

Doctoral Dissertations

Climatic warming is altering species distributions and ecosystem functions across the globe. Wood is an important carbon pool and the fungal communities in wood are relatively simple compared to those in soil. These factors make decomposing wood an ideal system for exploring the influence of decomposer community on the response of decomposition to warming. My research has focused on the effects of warming wood decomposition rates and wood decomposing communities. Using field and lab- based manipulative experiments and field observations I explore the influence of tree species, wood decomposition stage, geography and warming on fungal community structure and activity. In …

Effects Of Sugar-Amendment On Bacterial & Fungal Abundance In Native Vs. Nonnative-Dominated Soils Of A Puget Lowland Prairie, Jessica Wong

Summer Research

Scotch broom is a nonnative plant that has invaded the plant communities of the Pacific Northwest in the United States. It associates with bacteria in the soil to fix nitrogen from the atmosphere, thereby elevating soil nitrogen levels and encouraging the invasion of the community by other nonnative plants like itself. Researchers have used sugar-amendment to decrease soil nitrogen and restore native plant growth. Our study took place in Glacial Heritage Preserve, a Puget lowland prairie that has been invaded by broom in several areas. We aimed to investigate whether sugar-amendment increased or decreased bacterial and fungal abundance in native …

Farnesol Signaling In Candida Albicans, Melanie L. Langford

School of Biological Sciences: Dissertations, Theses, and Student Research

Candida albicans is a polymorphic fungus that causes a range of disease in humans, from mucosal infections to systemic disease. Its ability to cause disease is linked to conversion between yeast and filamentous forms of growth, and the first quorum-sensing molecule discovered in an eukaryote, farnesol, blocks this transition. In C. albicans, farnesol also kills mating-competent opaque cells, inhibits biofilm formation, protects the cells from oxidative stress, and can be a virulence factor or protective agent in disseminated and mucosal mouse models of infection, respectively. While much emphasis has been placed on determining its effect on C. albicans morphology, …