Environmental Microbiology and Microbial Ecology Commons^™

Spatial Variation In Carbon And Nitrogen In Cultivated Soils In Henan Province, China: Potential Effect On Crop Yield, Xuelin Zhang, Qun Wang, Frank S. Gilliam, Yilun Wang, Feina Cha, Chaohai Li

Biological Sciences Faculty Research

Improved management of soil carbon (C) and nitrogen (N) storage in agro-ecosystems represents an important strategy for ensuring food security and sustainable agricultural development in China. Accurate estimates of the distribution of soil C and N stores and their relationship to crop yield are crucial to developing appropriate cropland management policies. The current study examined the spatial variation of soil organic C (SOC), total soil N (TSN), and associated variables in the surface layer (0–40 cm) of soils from intensive agricultural systems in 19 counties within Henan Province, China, and compared these patterns with crop yield. Mean soil C and …

Advancing The Microbiome Research Community, Curtis Huttenhower, Rob Knight, C. Titus Brown, J. Gregory Caporaso, Jose C. Clemente, Dirk Gevers, Eric A. Franzosa, Scott T. Kelley, Dan Knights, Ruth E. Ley, Anup Mahurkar, Jacques Ravel, Scientists For Advancement Of Microbiome Research, Owen White, Jacques Izard

Department of Food Science and Technology: Faculty Publications

The human microbiome has become a recognized factor in promoting and maintaining health. We outline opportunities in interdisciplinary research, analytical rigor, standardization, and policy development for this relatively new and rapidly developing field. Advances in these aspects of the research community may in turn advance our understanding of human microbiome biology.

It is now widely recognized that disturbances in our normal microbial populations may be linked to acute infections such as Clostridium difficile and to chronic diseases such as heart disease, cancer, obesity, and autoimmune disorders. This has prompted substantial interest in the microbiome from both basic and clinical perspectives. …

Diversity Of Bacteria Carried By Pinewood Nematode In Usa And Phylogenetic Comparison With Isolates From Other Countries, Diogo Neves Proença, Luís Fonseca, Thomas Powers, Isabel M.O. Abrantes, Paula V. Morais

Department of Plant Pathology: Faculty Publications

Pine wilt disease (PWD) is native to North America and has spread to Asia and Europe. Lately, mutualistic relationship has been suggested between the pinewood nematode (PWN), Bursaphelenchus xylophilus the causal nematode agent of PWD, and bacteria. In countries where PWN occurs, nematodes from diseased trees were reported to carry bacteria from several genera. However no data exists for the United States. The objective of this study was to evaluate the diversity of the bacterial community carried by B. xylophilus, isolated from different Pinus spp. with PWD in Nebraska, United States. The bacteria carried by PWN belonged to Gammaproteobacteria …

Phylogenetic Diversity Of Microbial Isolates From The Mars Pathfinder, Kyla Bradylong, Adriana Blachowicz, Parag Vaishampayan, James N. Benardini, Wayne Schubert

STAR Program Research Presentations

As spacecraft are sent to different planets, they take with them microscopic pieces of life from Earth. It is the task of the Biotechnology and Planetary Protection Group to keep as much of this life off other planets as possible as well as document any life that may have been sent. During the construction of the Mars Pathfinder, samples were collected from various locations on the spacecraft to test for contamination. These samples were then isolated, grown, documented, preserved and their 16S rRNA genes were sequenced for identification. The 16S rRNA gene sequence is utilized because it is a highly …

The Show Cave Of Diros Vs. Wild Caves Of Peloponnese, Greece - Distribution Patterns Of Cyanobacteria, Vasiliki Lamprinou, Daniel B. Danielidis, Adriani Pantazidou, Alexandra Oikonomou, Athena Economou-Amilli

International Journal of Speleology

The karst cave ‘Vlychada’of Diros, one of the oldest show caves in Peloponnese, sustains extended phototrophic biofilms on various substrata – on rocks inside the cave including speleothems, and especially near the artificial lighting installation (‘Lampenflora’). After a survey of the main abiotic parameters (Photosynthetically Active Radiation -PAR, Temperature -T, Relative Humidity -RH, Carbon Dioxide -CO₂) three clusters of sampling sites were revealed according to Principal Component Analysis (PCA): i) the water gallery section predominately influenced by CO₂, ii) the dry passages influenced by RH and PAR, and iii) the area by the cave exit at …

Ammonia-Oxidizing Bacteria And Archaea Under Continuous Maize: The Influence Of Tillage, N Input And Aggregation On Abundance And Community Composition, Lauren Segal

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Nitrification involves the oxidation of ammonium (NH₄⁺) and is an important component of the overall N cycle. Nitrification occurs in two steps; first by oxidizing ammonium to nitrite, and then to nitrate. The first step is often the rate limiting step. Until recently ammonia-oxidizing bacteria (AOB) were thought to be the sole contributors to this process; however, the discovery of crenarchaeota, ammonia-oxidizing archaea (AOA), in marine environments has led to further study of their role in nitrification. Current literature supports the dominance of AOA over AOB in terrestrial ecosystems; however, little is known about what drives their …

Understanding The Factors Affecting Microbiological Quality Of Wheat Milled Products: From Wheat Fields To Milling Operations, Luis E. Sabillón Galeas

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Although regarded as a low-risk commodity, wheat flour-based mixes have been implicated in several food safety incidents. The present thesis is a compilation of five scientific manuscripts on the effect of weather variation, milling steps and implementation of pre-milling interventions on the microbiological quality and safety of wheat and milled products. The first manuscript is a review of the microbiological quality and safety of wheat-based products. Despite the low water activity, wheat flour may harbor dormant but viable microorganisms, which could lead to safety concerns when flour is used to produce refrigerated dough products. The second manuscript illustrates the effect …

Interactions Of Various Bacterial Populations With Chemical And Physical Factors From Seasonal Inputs And Outputs Of Retention Ponds, Felicia A. Krelwitz

All Student Theses and Dissertations

Retention ponds at Governors State University play an important role in collecting and treating storm water runoff before leaving campus and entering Thorn Creek. Many chemical and physical factors influence the diversity of bacterial populations in freshwater ecosystems. The main objective of this study was to compare the interactions of various bacterial populations with chemical and physical factors from seasonal inputs and outputs of Governors State University retention ponds before being discharged into Thorn Creek. The retention ponds studied include the Café Settling pond, Café pond and Beaver pond. Water and sediment were collected from inputs and outputs every other …

Anthropogenic Litter In Urban Freshwater Ecosystems: Distribution And Microbial Interactions, Timothy Hoellein, Miguel Rojas, Adam Pink, Joseph Gasior, John J. Kelly

Biology: Faculty Publications and Other Works

Accumulation of anthropogenic litter (i.e. garbage; AL) and its ecosystem effects in marine environments are well documented. Rivers receive AL from terrestrial habitats and represent a major source of AL to marine environments, but AL is rarely studied within freshwater ecosystems. Our objectives were to 1) quantify AL density in urban freshwaters, 2) compare AL abundance among freshwater, terrestrial, and marine ecosystems, and 3) characterize the activity and composition of AL biofilms in freshwater habitats. We quantified AL from the Chicago River and Chicago's Lake Michigan shoreline, and found that AL abundance in Chicago freshwater ecosystems was comparable to previously …

Identification And Characterization Of Phytoplankton In Barnegat Bay, New Jersey, Nicole L. Elia

Seton Hall University Dissertations and Theses (ETDs)

Barnegat Bay is a marine estuary that encompasses 670-square miles of the eastern coast of New Jersey. The bay serves as a home to thousands of species of plants, animals, and microorganisms. During the summer months, the population of the bay increases from 576,000 to over 1.5 million residents. In 2011, the Barnegat Bay Partnership reported that environmental conditions of the bay are declining due to increased pollutants from nutrient fertilizers and runoff. Increased nitrogen levels have led to eutrophication and proliferation of phytoplankton algal blooms. Harmful algal blooms (HABs) cause a decrease in dissolved oxygen levels in the water …

The Role Of Nitrogen And Phosphorus In The Growth, Toxicity, And Distribution Of The Toxic Cyanobacteria, Microcystis Aeruginosa, James Parrish

Master's Projects and Capstones

Microcystis aeruginosa is among the most common harmful algal-blooming species in the world. Potent microcystins released by M. aeruginosa have been linked to liver failure and death in aquatic mammals, like the endangered California sea otter, and provide a serious public health risk to humans. Once characterized as a freshwater problem, M. aeruginosa is expanding on a global scale, making persistent returns in freshwater, brackish, and coastal marine ecosystems. Though commonly observed dominating aquatic ecosystems in low N:P atomic ratios less than 44:1, the reliability of N:P ratios as a tool for managing and predicting M. aeruginosa blooms is explored …

Investigating Antibiotic Resistance Levels Of Salmonella Internalized In Lettuce Leaves, Jason B. Thomas

McNair Scholars Research Journal

Contamination of food crops by the human pathogen Salmonella is a food safety threat worldwide. Though using treated wastewater for irrigation is a sustainable practice, it may introduce trace levels of Salmonella that may contaminate food crops. Salmonella could develop resistance to antibiotics present in wastewater. The overall goal of the project is to increase the understanding of the public health risk associated with the use of treated wastewater to irrigate food crops. The objective of this particular study is to determine the antibiotic resistance level of Salmonella internalized in lettuce leaves. In this experiment, thirty-six plants of the lettuce …

Fruiting Bodies Of The Social Amoeba Dictyostelium Discoideum Increase Spore Transport By Drosophila, Jeff Smith, David C. Queller, Joan E. Strassmann

Biology Faculty Research

Background: Many microbial phenotypes are the product of cooperative interactions among cells, but their putative fitness benefits are often not well understood. In the cellular slime mold Dictyostelium discoideum , unicellular amoebae aggregate when starved and form multicellular fruiting bodies in which stress-resistant spores are held aloft by dead stalk cells. Fruiting bodies are thought to be adaptations for dispersing spores to new feeding sites, but this has not been directly tested. Here we experimentally test whether fruiting bodies increase the rate at which spores are acquired by passing invertebrates.
Results: Drosophila melanogaster accumulate spores on their surfaces more quickly …

Plant-Microbial Interactions Change Along A Prairie Restoration Chronosequence, Anna Herzberger

Undergraduate Honors Theses

Soil microbial communities are critical in determining the performance and density of species in plant communities. However, their role in regulating the success of restorations is much less clear. This study assessed the ability of soil microbial communities to regulate the growth and performance of two potentially dominant grasses and two common forbs in prairie restorations. Specifically, I examined the effects of soil microbial communities along a restoration chronosequence from agricultural fields to remnant prairies using experimentally inoculated soils. The two grass species, Andropogon gerardii and Sorghastrum nutans, produced larger biomass with the agricultural inoculates and experienced a decline …

Colonization Of Intestinal Pathogen Changes The Gut Microbiota, Kaitlyn Shondelmyer

Senior Honors Theses

Enterohemorrhagic Escherechia coli is a serious human pathogen causing bloody diarrhea and hemolytic uremic syndrome. It is difficult to study in animal models, but pathogenesis may be modeled in mice with the similar murine pathogen, Citrobacter rodentium. C. rodentium does not cause disease in streptomycin-treated mice, suggesting that it is competition with other facultative anaerobes that triggers pathogenesis. Streptomycin-treated mice were co-colonized with C. rodentium and a commensal E. coli strain. The intestinal microbiota of each group was observed over a 15-day period using quantitative PCR. Colon weights were also measured over the same period. Results indicate that the …

Bioremediation Of Crude Oil Spills Impacts Microbial Communities And The Magnetic Susceptibility Of Sediments, Carol L. Beaver, Anja Williams, Estella Atekwana, Gamal Abdel Aal, Farag Mewafy, Lee Slater, Silvia Rossbach

Research and Creative Activities Poster Day

A worldwide increase in the production, shipment, and storage of crude oil has led to an increase in oil spills, and efforts to physically remove this oil from the environment are often insufficient. As a result, hydrocarbon contamination that is not eliminated by suction, excavation, or by dispersants remains in the water and sediments to be degraded by microbes. Initially, the bioremediation of oil occurs aerobically, but as oxygen is depleted, microbes must switch to alternate electron acceptors. Gradients of terminal electron acceptors form over time, which in conjunction with the toxic properties of oil, have an effect on the …

Biosorption Of Heavy Metals Onto The Surface Of Bacteriophage T4, Zheng Huan Tan

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

Biosorption of heavy metals by bacterial and eukaryotic cell surfaces and the subsequent transport in aqueous environments is well recognized. However, very little is known about the roles viruses play in biosorption. Viruses outnumber prokaryotes and eukaryotes in environmental systems. These organisms represent abundant nanoparticulate organic colloids with reactive surfaces. Here we conducted a series of experiments to assess the biosorption potential of Escherichia coli bacteriophage T4. Adsorption of a heavy metal, Zn²⁺, to the surface of phage T4 was tested in a series of purified phage/metal solutions (0 µM – 1000 µM at 23°C). The Langmuir isotherm …

Deletion Mutant Library For Investigation Of Functional Outputs Of Cyclic Diguanylate Metabolism In Pseudomonas Aeruginosa Pa14, Dae-Gon Ha, Megan E. Richman, George A. O'Toole

Dartmouth Scholarship

We constructed a library of in-frame deletion mutants targeting each gene in Pseudomonas aeruginosa PA14 predicted to participate in cyclic di-GMP (c-di-GMP) metabolism (biosynthesis or degradation) to provide a toolkit to assist investigators studying c-di-GMP-mediated regulation by this microbe. We present phenotypic assessments of each mutant, including biofilm formation, exopolysaccharide (EPS) production, swimming motility, swarming motility, and twitch motility, as a means to initially characterize these mutants and to demonstrate the potential utility of this library.

Transcriptome Analysis Of Listeria Monocytogenes Exposed To Biocide Stress Reveals A Multi-System Response Involving Cell Wall Synthesis, Sugar Uptake, And Motility, Aidan Casey, Edward M. Fox, Stephan Schmitz-Esser, Aidan Coffey, Olivia Mcauliffe, Kieran Jordan

Department of Biological Sciences Publications

Listeria monocytogenes is a virulent food-borne pathogen most often associated with the consumption of “ready-to-eat” foods. The organism is a common contaminant of food processing plants where it may persist for extended periods of time. A commonly used approach for the control of Listeria monocytogenes in the processing environment is the application of biocides such as quaternary ammonium compounds. In this study, the transcriptomic response of a persistent strain of L. monocytogenes (strain 6179) on exposure to a sub-lethal concentration of the quaternary ammonium compound benzethonium chloride (BZT) was assessed. Using RNA-Seq, gene expression levels were quantified by sequencing …

Gene And Protein Sequence Optimization For High-Level Production Of Fully Active And Aglycosylated Lysostaphin In Pichia Pastoris, Hongliang Zhao, Kristina Blazanovic, Yoonjoo Choi, Chris Bailey-Kellogg, Karl E. Griswold

Dartmouth Scholarship

Lysostaphin represents a promising therapeutic agent for the treatment of staphylococcal infections, in particular those of methicillin-resistant Staphylococcus aureus (MRSA). However, conventional expression systems for the enzyme suffer from various limitations, and there remains a need for an efficient and cost-effective production process to facilitate clinical translation and the development of nonmedical applications. While Pichia pastoris is widely used for high-level production of recombinant proteins, there are two major barriers to the production of lysostaphin in this industrially relevant host: lack of expression from the wild-type lysostaphin gene and aberrant glycosylation of the wild-type protein sequence. The first barrier can …