Bacteriology Commons^™

Evolution Of Antibiotic Responses During Chronic P. Aeruginosa Infections In The Human Lung, David Frank Ritz

Dartmouth College Ph.D Dissertations

Typical antibiotic susceptibility testing (AST) of microbial samples is performed in homogeneous cultures in batch environments, which does not account for the highly heterogeneous and dynamic nature of antibiotic responses. The most common mutation found in P. aeruginosa lineages evolved during chronic cystic fibrosis infections in the human lung, a loss of function of repressor MexZ, increases basal levels of multidrug efflux MexXY, but does not increase resistance by traditional minimal inhibitory concentration (MIC) assays. Here, we use single cell microfluidics to show that P. aeruginosa’s response to aminoglycosides is highly heterogeneous, with only a subpopulation of cells surviving exposure. …

Population Genomics And Evolution Of Pseudomonas Aeruginosa, Samara T. Choudhury

Electronic Theses & Dissertations (2024 - present)

Pseudomonas aeruginosa is a Gram-negative bacterium ubiquitous in diverse environments and an opportunistic pathogen in humans. It is a leading cause of chronic lung infections in cystic fibrosis patients and of hospital-acquired pneumonia and sepsis. With a large flexible genome and abundant mobile genetic elements, P. aeruginosa exhibits high levels of antimicrobial resistance (AMR), making it a significant public health threat. Evolutionary processes such as homologous recombination, and horizontal gene transfer generate extensive genomic diversity in this species and facilitate the spread of resistance genes. In this dissertation, I investigate the genetic and evolutionary factors shaping P. aeruginosa population structure …

From Epidemics To Experimental Treatments: Amphibian Mass Mortality Events And A Potential Treatment For Chytridiomycosis, Daniel Callahan

Graduate Masters Theses

Worldwide, amphibian populations have experienced dramatic declines due to a variety of threats. Among them, disease has been particularly deleterious and continues to impact populations. In the United States and Canada, the three leading causes of amphibian mass mortality events are ranavirosis, chytridiomycosis, and severe perkinsea infection, all caused by infectious pathogens. While research and policy have helped populations recover from these diseases, more work needs to be done to develop practical and efficient treatments for these infections. Of these three diseases, chytridiomycosis has had the most devastating effects on amphibian populations globally. Caused by the chytrid fungi Batrachochytrium dendrobatidis …

Lmpact Of Salmonella Enterica Effector Proteins On Plant Physiology And Immunity, Sara Qader

Honors Theses

Salmonella enterica serovar Typhimurium are primarily recognized as pathogens associated with foodborne illnesses in humans. Salmonella also can colonize plant tissue effectively. The pathogen relies on type III secretion systems (T3SS) to infect mammals and plants successfully and counteract the immune response. Understanding the molecular mechanisms underlying Salmonella’s interactions with plants is essential for developing effective strategies to reduce its impact on human health and agriculture. Effector proteins, known for their role in modulating host-pathogen interactions, have been implicated in the virulence and pathogenicity of Salmonella. However, their specific functions and contributions to Salmonella’s interactions with plants remain largely unknown. …

Fiddler Crab Gut Microbiomes As An Indicator For Eutrophication Due To Waste-Water Contamination In Estuaries, Madison L. Geraci

Honors Theses

Estuaries are unique biogeochemical zones in coastal systems that provide a myriad of ecological functions: providing habitat for critically important fishery species, diverse species of plants and animals, and contributing to nutrient cycling. Estuaries are vulnerable to anthropogenic stressors as they are intersections between marine and terrestrial communities and are often the hotspot of coastal development and activity. Estuarine sediments act as repositories for anthropogenic contaminants, including excess nutrient runoffs and waste-water pollution that can cause states of eutrophication. Microorganisms are sensitive to these environmental changes, presenting a unique opportunity of being useful bioindicators of environmental stress. Isolating microorganisms from …

Social Interactions And Spatial Structure Drive Community Assembly Of Bacterial Biofilm, Matthew C. Bond

Dartmouth College Ph.D Dissertations

Despite the critical nature which microbial communities play in the natural world and human civilization, the breadth of understanding remains shallow. Challenged by scale, high variability between environments, and extensive diversity, microbial ecologists strive to understand connections between a community’s structure and function, as well as the ecological and evolutionary mechanisms underlying observed natural patterning of communities. Biofilms are the predominate mode of growth for microbial communities—characterized by cellular attachment to a surface via a self-produced matrix and heterogeneous structure, often resulting in a primary growth front along the biofilm surface due to differential access to bulk nutrients (cite). This …

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …

Breaking Virulent: The Coincidental Evolution Of Virulence Factors In Bacteria., Rhiannon Emmanuelle Cecil

Electronic Theses and Dissertations

Understanding how innocuous organisms can evolve to be pathogenic to humans is of increasing global concern. Further, understanding how existing pathogens may evolved to be more virulent is also vital to our ability to provide healthcare to people afflicted with diseases that promote chronic bacterial infections, such as cystic fibrosis. With the rise of antibiotic resistance in both bacteria and fungi it is paramount that new therapeutics are identified. Understanding what mutations occur that result in increased virulence in microbes can potentially provide new targets for antimicrobial drugs to combat antibiotic resistance. The Coincidental Evolution Hypothesis is a fundamental hypothesis …

Sympatric Soil Microbe Interactions Between Streptomyces And Fusarium Isolates, Lehren A. Olk-Szost

All NMU Master's Theses

Interkingdom interactions between soil bacteria and fungi may play a critical role in occurrence of disease suppressive soils, yet our understanding of these interactions remains limited. Streptomyces are well-known producers of antimicrobial compounds important to medicine and agriculture. Production of these secondary metabolites is often mediated by quorum sensing. Most Streptomyces research occurs in single species experiments, yet new metabolites have been discovered in interspecies co-culture experiments. Interspecies, intergenic, and interkingdom co-culture research will likely reveal many valuable compounds, and strengthen our understanding of complex ecological interactions in soil microbiomes. Interactions between sympatric Streptomyces and Fusarium isolates from disease suppressive …

Causes And Consequences Of Lasr Mutant Selection In Pseudomonas Aeruginosa Populations, Dallas L. Mould

Dartmouth College Ph.D Dissertations

Change is the only constant in life, and these changes, though random in nature, can have consequences. Quorum sensing is heterogeneous in phenotype and prone to negative selection. In P. aeruginosa, the regulator LasR is frequently non-functional in phylogenetically diverse isolates. Through repeated experimental evolution and mathematical modeling, we show that differences in growth enable lasR mutant evolutionary success and this requires a system enabling metabolic choices, known as carbon catabolite repression (or catabolite repression). The differences in catabolite repression between wild type and lasR mutants enable altered metabolite preferences, and the resulting differences in metabolic states enable intraspecies …

Effect Of Temperature On The Microbiome Of A Laboratory Reared Colony Of Haemaphysalis Longicornis Ticks, Brianna Mitchell

Poster Presentations

Honors research poster.

Haemaphysalis longicornis is a species of tick native to eastern Asia, including eastern China, Japan, eastern Russia, and Korea. To date, it has invaded and has now established its existence in Australia, New Zealand, and several of the Pacific Islands. This species of tick has recently been introduced to the United States, having a confirmed sighting in November 2017 on a sheep farm in New Jersey and since establishing populations in 18 states along the east coast and Appalachia. Based on the existing locations of H. longicornis in its native regions, as well as in the United …

Reproductive Ecology And Microbial Communities From Wood Duck Nest Boxes In Georgia And Florida, Jake Shurba

All Theses

Wood ducks (Aix sponsa) are an important game species throughout the Atlantic Flyway that was nearly extirpated by the early 20^th century due to overhunting and the loss of habitat. Wood ducks are secondary cavity-nesters that utilize artificial nest boxes and natural cavities. It is reported that the use of nest boxes is likely what led to re-establishment of the species in North America. Where boxes are numerous, overuse of boxes by multiple hens throughout a nesting season can occur and result in a buildup of bacteria, parasites and other potentially detrimental pathogens that can impact egg …

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

Biology and Medicine Through Mathematics Conference

No abstract provided.

Microbial Diversity And Community Structure In Sediments Associated With The Seagrass (Thallassia Testudinum) In Apalachicola Bay, Florida, Rahma Ahmed, Thomas Mcelroy, Troy Mutchler

Symposium of Student Scholars

Seagrass is an angiosperm which provides many ecosystem services in coastal areas, such as providing food, shelter and nurseries for many species, and decreasing the impact of waves on shorelines. A global assessment reported that 29% of known seagrass meadows are in a state of decline due to the effects of human activity. Seagrass is commonly found in shallow marine waters where they form meadows containing a microbiome that plays an important role in providing nutrients for seagrass growth, though little is known about the microorganisms within the seagrass meadow sediments. Our project collected sediments from seagrass meadows and adjacent …

Characterization Of Streptomyces Nymphaeiformis Sp. Nov., And Its Taxonomic Relatedness To Other Polyhydroxybutyrate-Degrading Streptomycetes, Gary R. Hix, Muhammad S. Khan, Mikayla T. Miller, Elisha C. Napier, Allison L. O'Brien, Roger P. White, Stephen F. Baron Ph.D.

Biology Faculty Scholarship

A polyhydroxybutyrate (PHB)-degrading actinomycete, strain SFB5A^T, was identified as a species of Streptomyces based on its membrane fatty acid profile and the presence of LL-diaminopimelic acid in the cell wall. It formed sporulating mycelia on most agar media, but flat or wrinkled, moist colonies on trypticase soy agar. Spores were smooth, cylindrical, and borne on long, straight to flexuous chains. It produced a light brown diffusible pigment, but not melanin. Comparison of genomic digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values indicated that strain SFB5A^T was related to Streptomyces litmocidini JCM 4394^T , Streptomyces …

An Optimal Lysis Time Maximizes Bacteriophage Fitness In Quasi-Continuous Culture, Sherin Kannoly, Abhyudai Singh, John J. Dennehy

Publications and Research

Optimality models have a checkered history in evolutionary biology. While optimality models have been successful in providing valuable insight into the evolution of a wide variety of biological traits, a common objection is that optimality models are overly simplistic and ignore organismal genetics. We revisit evolutionary optimization in the context of a major bacteriophage life history trait, lysis time. Lysis time refers to the period spanning phage infection of a host cell and its lysis, whereupon phage progenies are released. Lysis time, therefore, directly determines phage fecundity assuming progeny assembly does not exhaust host resources prior to lysis. Noting that …

Degradation And Nitrogen Cycling In The Context Of Biodiversity-Ecosystem Function Relationships In The Inquiline Bacterial Community Of Darlingtonia Californica, Megan Teigen

Cal Poly Humboldt theses and projects

Biodiversity-ecosystem function (BEF) research aims to explain how species and their environments interact with each other. Microbial communities engage in vital biogeochemical pathways in a variety of natural ecosystems, and yet there are large knowledge gaps about the specific metabolic pathways in which they are involved. Degradation specifically contributes to nitrogen cycling globally through the breakdown of large organic nitrogen compounds into small inorganic nitrogen that is necessary for the survival of many other organisms. In this study, I focused on the degradative function of the inquiline microbial communities found within the carnivorous pitcher plant, Darlingtonia californica. Darlingtonia grows in …

Comparisons Of Oral, Intestinal, And Pancreatic Bacterial Microbiomes In Patients With Pancreatic Cancer And Other Gastrointestinal Diseases, Mei Chung, Naisi Zhao, Richard Meier, Devin C. Koestler, Guojun Wu, Erika De Castillo, Bruce J. Paster, Kevin Charpentier, Jacques Izard, Karl T. Kelsey, Dominique S. Michaud

Department of Food Science and Technology: Faculty Publications

Background: Oral microbiota is believed to play important roles in systemic diseases, including cancer. Methods: We collected oral samples (tongue, buccal, supragingival, and saliva) and pancreatic tissue or intestinal samples from 52 subjects, and characterized 16S rRNA genes using high-throughput DNA sequencing.

Results: Bray–Curtis plot showed clear separations between bacterial communities in the oral cavity and those in intestinal and pancreatic tissue samples. PERMANOVA tests indicated that bacterial communities from buccal samples were similar to supragingival and saliva samples, and pancreatic duct samples were similar to pancreatic tumor samples, but all other samples were significantly different from each …

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

Publications and Research

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 compare the …

High-Throughput Two-Stage Dereplication Of Cave Bacteria To Discover Novel Antibiotic Compounds, Alexander Archey

Williams Honors College, Honors Research Projects

Since their discovery over a century ago, antibiotics have been a staple of combating infectious diseases. However, bacteria develop resistance to antibiotics through a variety of mechanisms. Efforts to identify new antibiotics often fail by discovering already-known antibiotics, or failing to synthesize new antibiotics that are safe for clinical use. The aim of this research was to dereplicate bacteria- to screen for antibiotic production in- normally isolated in cave ecosystems. Using two new technologies, the Antibiotic Resistance Platform (ARP) and a data acquisition and bioinformatics technique (IDBac), my dereplicating method allowed high throughput of bacterial screening for antibiotics. In this …

Species Richness And Ecological Diversity Of Myxomycetes And Myxomycete-Like Organisms In The Tropical Forests Of Brazil, Isadora Lima Coelho

Graduate Theses and Dissertations

Tropical rain forests cover less than two percent of Earth's surface, yet they sustain the greatest diversity of living organisms on the planet. Tropical rain forests cover nearly 73% of the Brazilian territory and besides harboring some of the most biodiverse ecosystems on the planet, this vast area also houses about 83% of the Brazilian population. Approximately 175 million people live in urban and rural areas with fragments of coverage of these biomes which contributes to the loss of biodiversity that rapidly increases over the years. Furthermore, the majority of the taxonomic and ecological efforts to describe and protect the …

Taxonomic Features And Comparison Of The Gut Microbiome From Two Edible Fungus-Farming Termites (Macrotermes Falciger, M. Natalensis) Harvested In The Vhembe District Of Limpopo, South Africa, Stephanie L. Schnorr, Courney A. Hofman, Shandukani R. Netschifhefhe, Frances D. Duncan, Tanvi P. Honap, Julie Lesnik, Cecil M. Lewis

Anthropology Faculty Research

Background Termites are an important food resource for many human populations around the world, and are a good supply of nutrients. The fungus-farming ‘higher’ termite members of Macrotermitinae are also consumed by modern great apes and are implicated as critical dietary resources for early hominins. While the chemical nutritional composition of edible termites is well known, their microbiomes are unexplored in the context of human health. Here we sequenced the V4 region of the 16S rRNA gene of gut microbiota extracted from the whole intestinal tract of two Macrotermes sp. soldiers collected from the Limpopo region of South Africa. Results …

Culture-Based Analysis Of ‘Cave Silver’ Biofilms On Rocks In The Former Homestake Mine In South Dakota, Usa, Amanpreet K. Brar, David Bergmann

International Journal of Speleology

Tunnels in a warm, humid area of the 1478 m level of the Sanford Underground Research Facility (SURF), located in a former gold mine in South Dakota, USA, host irregular, thin whitish, iridescent biofilms, which appear superficially similar to ‘cave silver’ biofilms described from limestone and lava tube caves, despite the higher rock temperature (32°C) and differing rock surface (phyllite) present at SURF. In this study, we investigated the diversity of cultivable bacteria constituting the cave silver by using several media: CN agar, CN gellan gum and 0.1X R2A agar. The highest colony count (CFU/g of sample) was observed on …

Co-Occurrence Of Manganese Oxidase Genes Indicates Lateral Transfer Between Classes Of Proteobacteria, Jacob Olichney

Student Scholar Showcase

Pseudomonas putida GB-1 is a model organism for the study of manganese oxidation in bacteria, however, the frequency of co-localization of multiple known and suspected manganese oxidizing proteins, as well as their occurrence between species, is unknown. Eight different genes isolated from known manganese oxidizing bacteria (MnxG, MopA, McoA, PputGB1_2552, PputGB1_2553, MoxA, MofA, and Bacillus MnxG) were tested individually using BioPython and BLAST (Basic Local Alignment Search Tool) on multiple genomic databases. BLAST searches had an expect value cutoff of 1e-50, limiting gene homologs to those with high sequence similarity. The abundance of homologous genes across classes of proteobacteria point …

Impact Of Seasonal And Host-Related Factors On The Intestinal Microbiome And Cestode Community Of Sorex Cinereus And Sorex Monticola, Katelyn D. Cranmer

College of Graduate Studies: Theses & Dissertations

The intestinal microbiome of mammals plays a significant role in host health and response to environmental stimuli and can include both beneficial native bacteria as well as parasitic worms. In this study, I examined the intestinal cestode and bacterial communities of two closely related species of shrew, Sorex monticola and Sorex cinereus, over a six month period in 2016. Specimens were collected approximately every three weeks from May to October from the Sangre de Cristo Mountains in Cowles, New Mexico. A total of 79 shrews were prepared with the gastrointestinal tracts removed and flash-frozen in liquid nitrogen. An additional …

Identification Of Microbiota Associated With The Ectosymbiotic Community Structure Of The Appalachian Brook Crayfish (Cambarus Bartonii), Matthew M. Cooke 6268927, Luke T. Fischer, Taylor Griffin, Sherrie Jeffers

Montview Journal of Research & Scholarship

Microbes play a significant role in ecosystems, effecting the vital functions of other organisms, interspecies relationships, and population sizes. Based upon previous research (Skelton et al., 2016), it has been hypothesized that crayfish symbionts (branchiobdellidans) play a significant role in regulating the amount of microbiota associated with the host. A growing body of knowledge is known regarding both the condition of gill fouling and the annelid worm’s symbiotic relationship with the crayfish (Skelton et al., 2016; Skelton et al., 2016). However, there is little to no evidence available concerning the bacteria’s role in the process (Skelton et al., 2016). Microbial …

Functional Studies Of The E. Coli Proc And A Putative Ortholog Mrub_1345, Maureen Azar, Dr. Lori Scott

Meiothermus ruber Genome Analysis Project

This project is part of the Meiothermus ruber genome analysis project, which uses the bioinformatics tools associated with the Guiding Education through Novel Investigation –Annotation Collaboration Toolkit (GENI-ACT) to predict gene function. We investigated the biological function of Escherichia coli and Meiothermus ruber proC genes using the complementation assay. In this research project, mutants of varying severity to the functional state of the protein were developed. The results showed that two or more amino acid deletions reduced or eliminated ProC function. Amino acid substitutions, on the other hand, were not severe enough to impact ProC function. Double and triple mutants …

Mrub_2120, Mrub_2121, Mrub_2122, Mrub_2123 And Mrub_2124 Are Orthologs Of E. Coli Genes B3458, B3457, B3456, B3455 And B3454, Respectively, And Make Up An Operon That Codes For The Branched-Chain Amino Acid Abc Transporter In Meiothermus Ruber Dsm 1279, Aaron Jones, Madelyn Huber, Dr. Lori Scott

Meiothermus ruber Genome Analysis Project

In this project we investigated the biological function of the genes Mrub_2120, Mrub_2121, Mrub_2122, Mrub_2123 and Mrub_2124 (KEGG map number 02010). We predict these genes encode components of a branched-chain amino acid ATP Binding Cassette (ABC) transporter: 1) Mrub_2120 (DNA coordinates 2169247-2170416 on the reverse strand) encodes the branched-chain amino acid binding protein that is localized to the periplasm; 2) Mrub_2121 (DNA coordinates 2170433..2171353 on the reverse strand) encodes the first TMD; 3) Mrub_2122 (DNA coordinates 2171365..2172279 on the reverse strand) encodes the second TMD; 4) Mrub_2123 (DNA coordinates 2172276..2173028 on the reverse strand) encodes the first NBD; 5) Mrub_2124 …

Photosynthetic Activity Under Low Light, Danijela Lonco

Williams Honors College, Honors Research Projects

Are bacteria capable of undergoing oxygenic photosynthesis under low-light conditions inside of caves? Inside of an Australian cave, Chlorophyll f was recently discovered. This chlorophyll pigment was found to demonstrate the capability for photosynthesis, suggesting that Chlorophyll f extends the spectrum of usable light needed for oxygenic photosynthesis (Lars, 2015). Due to the findings in this study, a team went to Carlsbad Caverns to see if there were any bacteria capable of undergoing oxygenic photosynthesis under low light.

Presence Of The Cyanotoxin Microcystin In Arctic Lakes Of Southwestern Greenland, Jessica Trout-Haney, Zachary Wood, Kathryn Cottingham

Dartmouth Scholarship

Cyanobacteria and their toxins have received significant attention in eutrophic temperate and tropical systems where conspicuous blooms of certain planktonic taxa release toxins into fresh water, threatening its potability and safe use for recreation. Although toxigenic cyanobacteria are not confined to high nutrient environments, bloom-forming species, or planktonic taxa, these other situations are studied les often studied. For example, toxin production in picoplankton and benthic cyanobacteria—the predominant photoautotrophs found in polar lakes—is poorly understood. We quantified the occurrence of microcystin (MC, a hepatotoxic cyanotoxin) across 18 Arctic lakes in southwestern Greenland. All of the focal lakes contained detectable levels of …