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Environmental Microbiology and Microbial Ecology

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Articles 1051 - 1080 of 1214

Full-Text Articles in Microbiology

Detecting Shifts In Soil Microbial Community Structure And Function Post Landspread Of Manure Or Biosolids Containing Antimicrobial Chemicals, Kelly Lehnert, Sharon A. Clay, Susan Gibson, Volker Brozel Nov 2007

Detecting Shifts In Soil Microbial Community Structure And Function Post Landspread Of Manure Or Biosolids Containing Antimicrobial Chemicals, Kelly Lehnert, Sharon A. Clay, Susan Gibson, Volker Brozel

Agronomy, Horticulture and Plant Science Faculty Publications

Soil microbial diversity and community interaction play an indispensable role in 2,4-dichorophenoxyacetic acid (2,4-D) herbicide degradation. The addition of manure or municipal waste biosolids through landspreading may alter soil community structure and function if these materials contain antimicrobial chemicals like chlortetracycline (CTC), administered in livestock feed to promote animal growth and health or tetracycline (TET) utilized in human health. In this study, soil applied with manure collected from pigs fed standard CTC levels was compared to soil containing manure from control pigs fed no CTC, and a comparison of soil applied with biosolids containing TET or without TET to distinguish …

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Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Bryan Culbertson, Jaymie Krone, Erastus Gatebe, Norbert Furumo, Steven Daniel Oct 2007

Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Bryan Culbertson, Jaymie Krone, Erastus Gatebe, Norbert Furumo, Steven Daniel

Faculty Research & Creative Activity

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic …

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Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Bryan J. Culbertson, Jaymie Krone, Erastus Gatebe, Norbert C. Furumo, Steven L. Daniel Oct 2007

Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Bryan J. Culbertson, Jaymie Krone, Erastus Gatebe, Norbert C. Furumo, Steven L. Daniel

Faculty Research & Creative Activity

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic …

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Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Jaymie Krone, Norbert Furumo Oct 2007

Impact Of Carbon Sources On Growth And Oxalate Synthesis By The Phytopathogenic Fungus Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Jaymie Krone, Norbert Furumo

Faculty Research & Creative Activity

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic …

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Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson Sep 2007

Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson

Environmental Science and Management Faculty Publications and Presentations

We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with …

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The Effect Of Residue C:N Ratio On The Turnover Of N And C In Various Soil Organic Matter Fractions, Ana B. Wingeyer Sep 2007

The Effect Of Residue C:N Ratio On The Turnover Of N And C In Various Soil Organic Matter Fractions, Ana B. Wingeyer

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

Identifying soil organic matter (SOM) fractions that contribute to soil indigenous nitrogen (N) supply and understanding their turnover under different management constitute necessary tools toward an efficient N use. The objectives of this study were: i) trace the endpoint of carbon (C) flux from residue inputs into SOM; and ii) asses the role of the light fraction (LF), mobile humic acid (MHA) fraction and calcium humate (CaHA) fraction as N sources for heterotrophic decomposition of fresh plant residues with contrasting C:N ratio. A long-term aerobic soil incubation was carried out on 15N-labeled soil samples from Lincoln and Mead, NE. …

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Microbial Nitrogen Limitation Increases Decomposition, Joseph M. Craine, Carl Morrow, Noah Fierer Aug 2007

Microbial Nitrogen Limitation Increases Decomposition, Joseph M. Craine, Carl Morrow, Noah Fierer

Dartmouth Scholarship

With anthropogenic nutrient inputs to ecosystems increasing globally, there are long-standing, fundamental questions about the role of nutrients in the decomposition of organic matter. We tested the effects of exogenous nitrogen and phosphorus inputs on litter decomposition across a broad suite of litter and soil types. In one experiment, C mineralization was compared across a wide array of plants individually added to a single soil, while in the second, C mineralization from a single substrate was compared across 50 soils. Counter to basic stoichiometric decomposition theory, low N availability can increase litter decomposition as microbes use labile substrates to acquire …

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Dissecting Biological “Dark Matter” With Single-Cell Genetic Analysis Of Rare And Uncultivated Tm7 Microbes From The Human Mouth, Yann Marcy, Cleber C. Ouverney, Elisabeth M. Bik, Tina Lösekann, Natalia Ivanova, Hector Garcia Martin, Ernest Szeto, Darren Platt, Philip Hugenholtz, David A. Relman, Stephen R. Quake Jul 2007

Dissecting Biological “Dark Matter” With Single-Cell Genetic Analysis Of Rare And Uncultivated Tm7 Microbes From The Human Mouth, Yann Marcy, Cleber C. Ouverney, Elisabeth M. Bik, Tina Lösekann, Natalia Ivanova, Hector Garcia Martin, Ernest Szeto, Darren Platt, Philip Hugenholtz, David A. Relman, Stephen R. Quake

Faculty Publications, Biological Sciences

We have developed a microfluidic device that allows the isolation and genome amplification of individual microbial cells, thereby enabling organism-level genomic analysis of complex microbial ecosystems without the need for culture. This device was used to perform a directed survey of the human subgingival crevice and to isolate bacteria having rod-like morphology. Several isolated microbes had a 16S rRNA sequence that placed them in candidate phylum TM7, which has no cultivated or sequenced members. Genome amplification from individual TM7 cells allowed us to sequence and assemble >1,000 genes, providing insight into the physiology of members of this phylum. This approach …

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Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven Daniel, G. Hartman, E. Wagner, M. Plewa Jul 2007

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven Daniel, G. Hartman, E. Wagner, M. Plewa

Faculty Research & Creative Activity

No abstract provided.

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Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa Jul 2007

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa

Faculty Research & Creative Activity

No abstract provided.

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Apres Le Deluge: Microbial Landscape Of New Orleans After The Hurricanes, Fred C. Dobbs May 2007

Apres Le Deluge: Microbial Landscape Of New Orleans After The Hurricanes, Fred C. Dobbs

OES Faculty Publications

No abstract provided.

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Parasites Alter Community Structure, Chelsea L. Wood, James E. Byers, Kathryn L. Cottingham, Irit Altman May 2007

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 …

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Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo May 2007

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo

Faculty Research & Creative Activity

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

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Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven Daniel, Bryan Culbertson, Norbert Furumo May 2007

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven Daniel, Bryan Culbertson, Norbert Furumo

Faculty Research & Creative Activity

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

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Soil Microbial Community Response To Hexavalent Chromium In Planted And Unplanted Soil, Ioannis Ipsilantis, Mark S. Coyne May 2007

Soil Microbial Community Response To Hexavalent Chromium In Planted And Unplanted Soil, Ioannis Ipsilantis, Mark S. Coyne

Plant and Soil Sciences Faculty Publications

Theories suggest that rapid microbial growth rates lead to quicker development of metal resistance. We tested these theories by adding hexavalent chromium [Cr(VI)] to soil, sowing Indian mustard (Brassica juncea), and comparing rhizosphere and bulk soil microbial community responses. Four weeks after the initial Cr(VI) application we measured Cr concentration, microbial biomass by fumigation extraction and soil extract ATP, tolerance to Cr and growth rates with tritiated thymidine incorporation, and performed community substrate use analysis with BIOLOG GN plates. Exchangeable Cr(VI) levels were very low, and therefore we assumed the Cr(VI) impact was transient. Microbial biomass was reduced …

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Green Autofluorescence In Dinoflagellates, Diatoms, And Other Microalgae And Its Implications For Vital Staining And Morphological Studies, Ying Zhong Tang, Fred C. Dobbs Apr 2007

Green Autofluorescence In Dinoflagellates, Diatoms, And Other Microalgae And Its Implications For Vital Staining And Morphological Studies, Ying Zhong Tang, Fred C. Dobbs

OES Faculty Publications

Green autofluorescence (GAF) has been described in the short flagellum of golden and brown algae, the stigma of Euglenophyceae, and cytoplasm of different life stages of dinoflagellates and is considered by some researchers a valuable taxonomic feature for dinoflagellates. In addition, green fluorescence staining has been widely proposed or adopted to measure cell viability (or physiological state) in areas such as apoptosis of phytoplankton, pollutant stresses on algae, metabolic activity of algae, and testing treatment technologies for ships' ballast water. This paper reports our epifluorescence microscopic observations and quantitative spectrometric measurements of GAIT in a broad phylogenetic range of microalgae. …

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Enzymes As Feed Additive To Aid In Responses Against Eimeria Species In Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets With Different Protein Levels, J. Parker, E. O. Oviedo Rondon, Beatrice A. Clack, S. Clemente-Hernandez, J. Osborne, J. C. Remus, H. Kettunen, H. Makivuokko, E. M. Pierson Jan 2007

Enzymes As Feed Additive To Aid In Responses Against Eimeria Species In Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets With Different Protein Levels, J. Parker, E. O. Oviedo Rondon, Beatrice A. Clack, S. Clemente-Hernandez, J. Osborne, J. C. Remus, H. Kettunen, H. Makivuokko, E. M. Pierson

Faculty Publications

This research aimed to evaluate the effects of adding a combination of exogenous enzymes to starter diets varying in protein content and fed to broilers vaccinated at day of hatch with live oocysts and then challenged with mixed Eimeria spp. Five hundred four 1-d-old male Cobb-500 chickens were distributed in 72 cages. The design consisted of 12 treatments. Three anticoccidial control programs [ionophore (IO), coccidian vaccine (COV), and coccidia-vaccine + enzymes (COV + EC)] were evaluated under 3 CP levels (19, 21, and 23%), and 3 unmedicated-uninfected (UU) negative controls were included for each one of the protein levels. All …

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Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake Jan 2007

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake

Faculty Research & Creative Activity

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

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Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven Daniel, Christine Pilsl, Harold Drake Jan 2007

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven Daniel, Christine Pilsl, Harold Drake

Faculty Research & Creative Activity

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

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Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson Jan 2007

Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson

Scholarship and Professional Work - LAS

We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with …

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Sulfur-Oxidizing Bacteria In Soap Lake (Washington State), A Meromictic, Haloalkaline Lake With An Unprecedented High Sulfide Content, Dimitry Y. Sorokin, Mirjam Foti, Holly C. Pinkart, Gerard Muyzer Jan 2007

Sulfur-Oxidizing Bacteria In Soap Lake (Washington State), A Meromictic, Haloalkaline Lake With An Unprecedented High Sulfide Content, Dimitry Y. Sorokin, Mirjam Foti, Holly C. Pinkart, Gerard Muyzer

All Faculty Scholarship for the College of the Sciences

Culture-dependent and -independent techniques were used to study the diversity of chemolithoautotrophic sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake containing an unprecedentedly high sulfide concentration in the anoxic monimolimnion. Both approaches revealed the dominance of bacteria belonging to the genus Thioalkalimicrobium, which are common inhabitants of soda lakes. A dense population of Thioalkalimicrobium (up to 107 cells/ml) was found at the chemocline, which is characterized by a steep oxygen-sulfide gradient. Twelve Thioalkalimicrobium strains exhibiting three different phenotypes were isolated in pure culture from various locations in Soap Lake. The isolates fell into two groups …

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Comparison Study Of The Averaged Sediment Microbial Enzyme Activities In Four Fecally-Contaminated Streams In The Same Watershed In Northeast Tennessee To Biochemical Oxygen Demand, Nitrate Concentration, And Phosphate Concentration, Brian G. Evanshen, Kurt J. Maier, Phillip R. Scheuerman Jan 2007

Comparison Study Of The Averaged Sediment Microbial Enzyme Activities In Four Fecally-Contaminated Streams In The Same Watershed In Northeast Tennessee To Biochemical Oxygen Demand, Nitrate Concentration, And Phosphate Concentration, Brian G. Evanshen, Kurt J. Maier, Phillip R. Scheuerman

ETSU Faculty Works

Microbial enzyme activities (MEA’s) are measurements of microbial metabolism. These activities are dependent on the need for nutrients and respiration. This extended study evaluated four streams in the same watershed that had an approved fecal coliform Total Maximum Daily Load. Sediment and water samples were collected monthly for the first year of each specific stream study, and then quarterly to the end of 2006. Dehydrogenase, a measure of microbial respiration, along with acid phosphatase, alkaline phosphatase, galactosidase and glucosidase activities were measured using colorimetric assays. Biochemical oxygen demand (BOD) was determined using the standard 5-day test (BOD5). Nitrate …

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Microbiological Enhancement Of Phosphorus Sequestration In Iron-Enriched Sediments, Lindsay Marie Sandersfeld Jan 2007

Microbiological Enhancement Of Phosphorus Sequestration In Iron-Enriched Sediments, Lindsay Marie Sandersfeld

Honors Program Theses

An overabundance of phosphorus, primarily due to agricultural run off, is the source of increases in unwanted algae in Iowa's surface waters. Oxidized iron found in mine tailings will sequester phosphorus in sediments and prevent it from entering surface waters. Therefore, adding mine tailings to wetlands is a cheap and easy way to eliminate phosphorus pollution. This phosphorus removal process is enhanced by a microbial component that biochemically solubilizes iron tailings which allows them to efficiently react with free phosphorus in the water. The purpose of this project was to characterize the microbial component in this process. Ferric citrate medium …

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Vulnerability Of Pathogenic Biofilms To Micavibrio Aeruginosavorus, Daniel Kadouri, Nel C. Venzon, George A. O'Toole Nov 2006

Vulnerability Of Pathogenic Biofilms To Micavibrio Aeruginosavorus, Daniel Kadouri, Nel C. Venzon, George A. O'Toole

Dartmouth Scholarship

The host specificity of the gram-negative exoparasitic predatory bacterium Micavibrio aeruginosavorus was examined. M. aeruginosavorus preyed on Pseudomonas aeruginosa, as previously reported, as well as Burkholderia cepacia, Klebsiella pneumoniae, and numerous clinical isolates of these species. In a static assay, a reduction in biofilm biomass was observed as early as 3 hours after exposure to M. aeruginosavorus, and an ∼100-fold reduction in biofilm cell viability was detected following a a 24-h exposure to the predator. We observed that an initial titer of Micavibrio as low as 10 PFU/well or a time of exposure to the predator as short as 30 …

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Saccharomyces Cerevisiae-Based Molecular Tool Kit For Manipulation Of Genes From Gram-Negative Bacteria, Robert M. Q. Shanks, Nicky C. Caiazza, Shannon M. Hinsa, Christine M. Toutain, George A. O'Toole Jul 2006

Saccharomyces Cerevisiae-Based Molecular Tool Kit For Manipulation Of Genes From Gram-Negative Bacteria, Robert M. Q. Shanks, Nicky C. Caiazza, Shannon M. Hinsa, Christine M. Toutain, George A. O'Toole

Dartmouth Scholarship

A tool kit of vectors was designed to manipulate and express genes from a wide range of gram-negative species by using in vivo recombination. Saccharomyces cerevisiae can use its native recombination proteins to combine several amplicons in a single transformation step with high efficiency. We show that this technology is particularly useful for vector design. Shuttle, suicide, and expression vectors useful in a diverse group of bacteria are described and utilized. This report describes the use of these vectors to mutate clpX and clpP of the opportunistic pathogen Pseudomonas aeruginosa and to explore their roles in biofilm formation and surface …

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Microbial Ecology Of An Animal Waste-Fueled Induced Blanket Reactor, Steven C. Curtis May 2006

Microbial Ecology Of An Animal Waste-Fueled Induced Blanket Reactor, Steven C. Curtis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Use of an induced blanket reactor (IBR) to break down organic matter into methane is a financially attractive method to reduce the environmental impact of animal or industrial waste. In order to better understand the biological processes involved with the conversion of waste to biogas by an IBR, it is necessary to gain a better understanding of the microorganisms and their roles in the reactor. Molecular techniques based on the isolation of 16S rDNA were used in order to avoid the limitations posed by conventional culture-based techniques. Total DNA was extracted and amplified using universal primers specific to eubacteria and …

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Farnesol Restores Wild-Type Colony Morphology To 96% Of Candida Albicans Colony Morphology Variants Recovered Following Treatment With Mutagens, Ellen C. Jensen, Jacob M. Hornby, Nicole E. Pagliaccetti, Chuleeon M. Wolter, Kenneth Nickerson, Audrey L. Atkin Apr 2006

Farnesol Restores Wild-Type Colony Morphology To 96% Of Candida Albicans Colony Morphology Variants Recovered Following Treatment With Mutagens, Ellen C. Jensen, Jacob M. Hornby, Nicole E. Pagliaccetti, Chuleeon M. Wolter, Kenneth Nickerson, Audrey L. Atkin

Kenneth Nickerson Papers

Candida albicans is a diploid fungus that undergoes a morphological transition between budding yeast, hyphal, and pseudohyphal forms. The morphological transition is strongly correlated with virulence and is regulated in part by quorum sensing. Candida albicans produces and secretes farnesol that regulates the yeast to mycelia morphological transition. Mutants that fail to synthesize or respond to farnesol could be locked in the filamentous mode. To test this hypothesis, a collection of C. albicans mutants were isolated that have altered colony morphologies indicative of the presence of hyphal cells under environmental conditions where C. albicans normally grows only as yeasts. All …

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Analysis Of Bacterial Population And Distribution In The Developing Strata Of A Constructed Wetland Used For Chlorinated Ethene Bioremediation, Milton J. Clausen Jr. Mar 2006

Analysis Of Bacterial Population And Distribution In The Developing Strata Of A Constructed Wetland Used For Chlorinated Ethene Bioremediation, Milton J. Clausen Jr.

Theses and Dissertations

Chlorinated hydrocarbons and their degradation products are among of the most common organic groundwater contaminates in the United States. These compounds attack the central nervous system in animals and can affect the photosynthesis of plants. These compounds are also resistant to degradation in the environment and, because of this, pose a risk to any ecosystem in which they are present. This study identified the dominant microbial species in a constructed treatment wetland at Wright-Patterson AFB, Dayton, Ohio using 16S rRNA gene sequence analysis. Samples were taken from three different depths and during each of the four seasons. These samples were …

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Conservation Of The Pho Regulon In Pseudomonas Fluorescens Pf0-1, Russell D. Monds, Peter D. Newell, Julia A. Schwartzman, George A. O'Toole Mar 2006

Conservation Of The Pho Regulon In Pseudomonas Fluorescens Pf0-1, Russell D. Monds, Peter D. Newell, Julia A. Schwartzman, George A. O'Toole

Dartmouth Scholarship

The Pho regulon integrates the sensing of environmental inorganic phosphate (Pi) availability with coregulation of gene expression, mediating an adaptive response to Pi limitation. Many aspects of the Pho regulon have been addressed in studies of Escherichia coli; however, it is unclear how transferable this knowledge is to other bacterial systems. Here, we report work to discern the conservation of the Pho regulon in Pseudomonas fluorescens Pf0-1. We demonstrate by mutational studies that PhoB/PhoR and the Pst system have conserved functions in the regulation of Pi-induced phosphatase activities, as well as expression of other Pi-regulated genes. A genetic screen was …

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Bacteriophage Migration Via Nematode Vectors: Host-Parasite-Consumer Interactions In Laboratory Microcosms, John J. Dennehy, Nicholas A. Friedenberg, Yul W. Yang, Paul E. Turner Mar 2006

Bacteriophage Migration Via Nematode Vectors: Host-Parasite-Consumer Interactions In Laboratory Microcosms, John J. Dennehy, Nicholas A. Friedenberg, Yul W. Yang, Paul E. Turner

Dartmouth Scholarship

Pathogens vectored by nematodes pose serious agricultural, economic, and health threats; however, little is known of the ecological and evolutionary aspects of pathogen transmission by nematodes. Here we describe a novel model system with two trophic levels, bacteriophages and nematodes, each of which competes for bacteria. We demonstrate for the first time that nematodes are capable of transmitting phages between spatially distinct patches of bacteria. This model system has considerable advantages, including the ease of maintenance and manipulation at the laboratory bench, the ability to observe many generations in short periods, and the capacity to freeze evolved strains for later …

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