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Microbial Physiology

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Articles 211 - 236 of 236

Full-Text Articles in Microbiology

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 …


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 …


Susceptibility Of Biofilms To Bdellovibrio Bacteriovorus Attack, Daniel Kadouri, George A. O'Toole Jul 2005

Susceptibility Of Biofilms To Bdellovibrio Bacteriovorus Attack, Daniel Kadouri, George A. O'Toole

Dartmouth Scholarship

Biofilms are communities of microorganisms attached to a surface, and the growth of these surface attached communities is thought to provide microorganisms with protection against a range of biotic and abiotic agents. The capability of the gram-negative predatory bacterium Bdellovibrio bacteriovorus to control and reduce an existing Escherichia coli biofilm was evaluated in a static assay. A reduction in biofilm biomass was observed as early as 3 h after exposure to the predator, and an 87% reduction in crystal violet staining corresponding to a 4-log reduction in biofilm cell viability was seen after a 24-h exposure period. We observed that …


Development And Characterization Of Eukaryotic Biomimetic Liposomes, Bradley Jay Taylor May 2004

Development And Characterization Of Eukaryotic Biomimetic Liposomes, Bradley Jay Taylor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study developed and characterized phospholipid vesicles, or liposomes, that mimic cell surfaces. Microemulsified liposomes contained biotinylated phosphatidylethanolamine, allowing them to be immobilized to avidin-coated glass. Laminin (LN), glycosphingolipids (GMl and GM3), and Escherichia coli's mechanosensitive channel of large conductance (EcoMscL) were embedded into liposome membranes. It was determined whether these embedded molecules exhibited their physiological roles of adhesion, cell recognition, and mechanosensation, respectively. Confocal laser scanning microscopy (CLSM) was employed to examine the interaction of fluorescently probed proteins, toxins, and bacteria with the immobilized microemulsified liposomes. Capture of individual and simultaneous multiple species of bacteria by GMl, GM3, …


Physiology Of The Thermophilic Acetogen Moorella Thermoacetica, Harold L. Drake, Steven L. Daniel Apr 2004

Physiology Of The Thermophilic Acetogen Moorella Thermoacetica, Harold L. Drake, Steven L. Daniel

Steven L. Daniel

Moorella thermoacetica (originally isolated as Clostridium thermoaceticum) has served as the primary acetogenic bacterium for the resolution of the acetyl coenzyme A (acetyl-CoA) orWood–Ljungdahl pathway, a metabolic pathway that (i) autotrophically assimilates CO2 and (ii) is centrally important to the turnover of carbon in many habitats. The purpose of this article is to highlight the diverse physiological features of this model acetogen and to examine some of the consequences of its metabolic capabilities.


Physiology Of The Thermophilic Acetogen Moorella Thermoacetica, Harold L. Drake, Steven L. Daniel Apr 2004

Physiology Of The Thermophilic Acetogen Moorella Thermoacetica, Harold L. Drake, Steven L. Daniel

Faculty Research & Creative Activity

Moorella thermoacetica (originally isolated as Clostridium thermoaceticum) has served as the primary acetogenic bacterium for the resolution of the acetyl coenzyme A (acetyl-CoA) orWood–Ljungdahl pathway, a metabolic pathway that (i) autotrophically assimilates CO2 and (ii) is centrally important to the turnover of carbon in many habitats. The purpose of this article is to highlight the diverse physiological features of this model acetogen and to examine some of the consequences of its metabolic capabilities.


Physiology Of The Thermophilic Acetogen Moorella Thermoacetica, Harold Drake, Steven Daniel Apr 2004

Physiology Of The Thermophilic Acetogen Moorella Thermoacetica, Harold Drake, Steven Daniel

Faculty Research & Creative Activity

Moorella thermoacetica (originally isolated as Clostridium thermoaceticum) has served as the primary acetogenic bacterium for the resolution of the acetyl coenzyme A (acetyl-CoA) orWood–Ljungdahl pathway, a metabolic pathway that (i) autotrophically assimilates CO2 and (ii) is centrally important to the turnover of carbon in many habitats. The purpose of this article is to highlight the diverse physiological features of this model acetogen and to examine some of the consequences of its metabolic capabilities.


Oxalate Metabolism By The Acetogenic Bacterium Moorella Thermoacetica, Steven L. Daniel, Christine Pilsl, Harold L. Drake Feb 2004

Oxalate Metabolism By The Acetogenic Bacterium Moorella Thermoacetica, Steven L. Daniel, Christine Pilsl, Harold L. Drake

Steven L. Daniel

Whole-cell and cell-extract experiments were performed to study the mechanism of oxalate metabolism in the acetogenic bacterium Moorella thermoacetica. In short-term, whole-cell assays, oxalate consumption was low unless cell suspensions were supplemented with CO2, KNO3, or Na2S2O3. Cell extracts catalyzed the oxalate-dependent reduction of benzyl viologen. Oxalate consumption occurred concomitant to benzyl viologen reduction; when benzyl viologen was omitted, oxalate was not appreciably consumed. Based on benzyl viologen reduction, specific activities of extracts averaged 0.6 μmol oxalate oxidized min−1 mg protein−1. Extracts also catalyzed the formate-dependent reduction of NADP+; however, oxalate-dependent reduction of NADP+ was negligible. Oxalate- or formate-dependent reduction …


Oxalate Metabolism By The Acetogenic Bacterium Moorella Thermoacetica, Steven Daniel, Christine Pilsl, Harold Drake Feb 2004

Oxalate Metabolism By The Acetogenic Bacterium Moorella Thermoacetica, Steven Daniel, Christine Pilsl, Harold Drake

Faculty Research & Creative Activity

Whole-cell and cell-extract experiments were performed to study the mechanism of oxalate metabolism in the acetogenic bacterium Moorella thermoacetica. In short-term, whole-cell assays, oxalate consumption was low unless cell suspensions were supplemented with CO2, KNO3, or Na2S2O3. Cell extracts catalyzed the oxalate-dependent reduction of benzyl viologen. Oxalate consumption occurred concomitant to benzyl viologen reduction; when benzyl viologen was omitted, oxalate was not appreciably consumed. Based on benzyl viologen reduction, specific activities of extracts averaged 0.6 μmol oxalate oxidized min−1 mg protein−1. Extracts also catalyzed the formate-dependent reduction of NADP+; however, oxalate-dependent reduction of NADP+ was negligible. Oxalate- or formate-dependent reduction …


Oxalate Metabolism By The Acetogenic Bacterium Moorella Thermoacetica, Steven L. Daniel, Christine Pilsl, Harold L. Drake Feb 2004

Oxalate Metabolism By The Acetogenic Bacterium Moorella Thermoacetica, Steven L. Daniel, Christine Pilsl, Harold L. Drake

Faculty Research & Creative Activity

Whole-cell and cell-extract experiments were performed to study the mechanism of oxalate metabolism in the acetogenic bacterium Moorella thermoacetica. In short-term, whole-cell assays, oxalate consumption was low unless cell suspensions were supplemented with CO2, KNO3, or Na2S2O3. Cell extracts catalyzed the oxalate-dependent reduction of benzyl viologen. Oxalate consumption occurred concomitant to benzyl viologen reduction; when benzyl viologen was omitted, oxalate was not appreciably consumed. Based on benzyl viologen reduction, specific activities of extracts averaged 0.6 μmol oxalate oxidized min−1 mg protein−1. Extracts also catalyzed the formate-dependent reduction of NADP+; however, oxalate-dependent reduction of NADP+ was negligible. Oxalate- or formate-dependent reduction …


The Deadly Trypanosome: Understanding The Parasite That Causes Sleeping Sickness, Patricia E. Mancini Jun 2002

The Deadly Trypanosome: Understanding The Parasite That Causes Sleeping Sickness, Patricia E. Mancini

Bridgewater Review

No abstract provided.


Kinetic Characterization Of Tetracycline Binding And Release By Demineralized Bone - Dfdba, Orner Kabil Apr 2000

Kinetic Characterization Of Tetracycline Binding And Release By Demineralized Bone - Dfdba, Orner Kabil

Biological Sciences Theses & Dissertations

The microbial etiology of periodontal diseases has led to widespread research in the development of methods and local delivery systems to increase the efficacy of antibiotic therapy. Several drug delivery systems employing biodegradable and nonbiodegradable carriers have been shown to release antibiotics directly into periodontal pockets. The purpose of this study was to determine the binding and release kinetics of tetracycline by demineralized bone. Further aspects of the study include in vitro evaluation of DFDBA (demineralized freeze-dried bone allografts) as a tetracycline carrier system for periodontal therapy. Experiments were performed which employed different tetracycline concentrations with constant amounts of bone …


A New Genetic Locus In Sinorhizobium Meliloti Is Involved In Stachydrine Utilization, Donald A. Phillips Dr., Eve S. Sandee Dr., Jan A.C. Vriezen Dr., Frans J. Debruijn Dr., Daniel Lerudulier Dr., Cecillia M. Joseph Dr. Jan 1998

A New Genetic Locus In Sinorhizobium Meliloti Is Involved In Stachydrine Utilization, Donald A. Phillips Dr., Eve S. Sandee Dr., Jan A.C. Vriezen Dr., Frans J. Debruijn Dr., Daniel Lerudulier Dr., Cecillia M. Joseph Dr.

Jan A.C. Vriezen Dr.

Stachydrine, a betaine released by germinating alfalfa seeds, functions as an inducer of nodulation genes, a catabolite, and an osmoprotectant in Sinorhizobium meliloti. Two stachydrine-inducible genes were found in S. meliloti 1021 by mutation with a Tn5-luxAB promoter probe. Both mutant strains (S10 and S11) formed effec- tive alfalfa root nodules, but neither grew on stachydrine as the sole carbon and nitrogen source. When grown in the absence or presence of salt stress, S10 and S11 took up [14C]stachydrine as well as wild-type cells did, but neither used stachydrine effectively as an osmoprotectant. In the absence of salt stress, both …


Biotransformation Of Bile Acids, Cholesterol And Steroids. Chapter 13 In: The Ecology And Physiology Of Gastrointestinal Microbes. Vol. 1, New York, Chapman And Hall., Stephen Baron, Phillip B. Hylemon Jan 1995

Biotransformation Of Bile Acids, Cholesterol And Steroids. Chapter 13 In: The Ecology And Physiology Of Gastrointestinal Microbes. Vol. 1, New York, Chapman And Hall., Stephen Baron, Phillip B. Hylemon

Biology Faculty Scholarship

No abstract provided.


Hypercholesterolemia And Platelet Sensitivity To Thromb In-Induced Aggregation In Whole Blood, Charles E. Hammond Ii Aug 1989

Hypercholesterolemia And Platelet Sensitivity To Thromb In-Induced Aggregation In Whole Blood, Charles E. Hammond Ii

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Arts and Sciences at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Sciences in Biology by Charles E. Hammond, II on August 1, 1989.


Protoporphyrinogen Oxidation, A Step In Heme Synthesis In Soybean Root Nodules And Free-Living Rhizobia., Nicholas J. Jacobs, Susan E. Borotz, Mary Lou Guerinot Jan 1989

Protoporphyrinogen Oxidation, A Step In Heme Synthesis In Soybean Root Nodules And Free-Living Rhizobia., Nicholas J. Jacobs, Susan E. Borotz, Mary Lou Guerinot

Dartmouth Scholarship

Extracts of the crude bacteroid fraction of symbiotically grown Bradyrhizobium japonicum were much more active in oxidizing protoporphyrinogen to protoporphyrin than were extracts of cells grown under free-living conditions, especially when assayed in atmospheres containing only traces of oxygen. This correlates with the higher heme content of the microaerophilic nodules. Furthermore, the high level of oxidative activity in the crude bacteroid fraction was associated with an uncharacterized membrane fraction, probably of plant origin, that was separable from the bacteroids by Percoll gradient centrifugation.


Microbial Degradation Of Oxalate In The Gastrointestinal Tracts Of Rats, Steven L. Daniel Aug 1987

Microbial Degradation Of Oxalate In The Gastrointestinal Tracts Of Rats, Steven L. Daniel

Steven L. Daniel

Rates of oxalate degradation by mixed bacterial populations in cecal contents from wlld rats ranged from 2.5 to 20.6 µmol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 µmollg (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. Wben Sprague-Pawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 µmollg (dry weight) per …


Carbon Monoxide-Dependent Chemolithotrophic Growth Of Clostridium Thermoautotrophicum, M. Dean Savage, Zhongren Wu, Steven L. Daniel, Leon L. Lundie Jr, Harold L. Drake Aug 1987

Carbon Monoxide-Dependent Chemolithotrophic Growth Of Clostridium Thermoautotrophicum, M. Dean Savage, Zhongren Wu, Steven L. Daniel, Leon L. Lundie Jr, Harold L. Drake

Steven L. Daniel

The acetogen Clostridium thermoautotrophicum was cultivated under CO-dependent chemolithotrophic conditions. CO-dependent growth profiles and energetics indicated that supplemental CO2 was fundamental to efficient growth at the expense of CO. Overall product stoichiometry approximated 6.5CO --> CH3CO2H + 3.5CO2 + 0.6 cell C + 0.5 unrecovered C. Initial CO/CO2 ratios of 2 to 4 yielded optimal doubling times and cell yields. Maximal YCO values approximated 2.5 g of cell dry weight per mol of CO consumed; Y H2 , was considerably lower than Y CO Cross-transfer growth experiments and protein profiles indicated differential expression of genes between CO and methanol cultures.


Carbon Monoxide-Dependent Chemolithotrophic Growth Of Clostridium Thermoautotrophicum, M. Dean Savage, Zhongren Wu, Steven L. Daniel, Leon L. Lundie Jr, Harold L. Drake Aug 1987

Carbon Monoxide-Dependent Chemolithotrophic Growth Of Clostridium Thermoautotrophicum, M. Dean Savage, Zhongren Wu, Steven L. Daniel, Leon L. Lundie Jr, Harold L. Drake

Faculty Research & Creative Activity

The acetogen Clostridium thermoautotrophicum was cultivated under CO-dependent chemolithotrophic conditions. CO-dependent growth profiles and energetics indicated that supplemental CO2 was fundamental to efficient growth at the expense of CO. Overall product stoichiometry approximated 6.5CO --> CH3CO2H + 3.5CO2 + 0.6 cell C + 0.5 unrecovered C. Initial CO/CO2 ratios of 2 to 4 yielded optimal doubling times and cell yields. Maximal YCO values approximated 2.5 g of cell dry weight per mol of CO consumed; Y H2 , was considerably lower than Y CO Cross-transfer growth experiments and protein profiles indicated differential expression of genes between CO and methanol cultures.


Microbial Degradation Of Oxalate In The Gastrointestinal Tracts Of Rats, Steven L. Daniel Aug 1987

Microbial Degradation Of Oxalate In The Gastrointestinal Tracts Of Rats, Steven L. Daniel

Faculty Research & Creative Activity

Rates of oxalate degradation by mixed bacterial populations in cecal contents from wlld rats ranged from 2.5 to 20.6 µmol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 µmollg (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. Wben Sprague-Pawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 µmollg (dry weight) per …


Microbial Degradation Of Oxalate In The Gastrointestinal Tracts Of Rats, Steven Daniel Aug 1987

Microbial Degradation Of Oxalate In The Gastrointestinal Tracts Of Rats, Steven Daniel

Faculty Research & Creative Activity

Rates of oxalate degradation by mixed bacterial populations in cecal contents from wlld rats ranged from 2.5 to 20.6 µmol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 µmollg (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. Wben Sprague-Pawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 µmollg (dry weight) per …


Carbon Monoxide-Dependent Chemolithotrophic Growth Of Clostridium Thermoautotrophicum, M. Savage, Zhongren Wu, Steven Daniel, Leon Lundie, Harold Drake Aug 1987

Carbon Monoxide-Dependent Chemolithotrophic Growth Of Clostridium Thermoautotrophicum, M. Savage, Zhongren Wu, Steven Daniel, Leon Lundie, Harold Drake

Faculty Research & Creative Activity

The acetogen Clostridium thermoautotrophicum was cultivated under CO-dependent chemolithotrophic conditions. CO-dependent growth profiles and energetics indicated that supplemental CO2 was fundamental to efficient growth at the expense of CO. Overall product stoichiometry approximated 6.5CO --> CH3CO2H + 3.5CO2 + 0.6 cell C + 0.5 unrecovered C. Initial CO/CO2 ratios of 2 to 4 yielded optimal doubling times and cell yields. Maximal YCO values approximated 2.5 g of cell dry weight per mol of CO consumed; Y H2 , was considerably lower than Y CO Cross-transfer growth experiments and protein profiles indicated differential expression of genes between CO and methanol cultures.


Comparison Of Surface Polysaccharides Of R. Leguminosarum Anu57 (Exo-1), R. Leg. Anu57(Pbr1an) (Nod+, Nif-), And R. Leg. Anu57(Pjb5j1) (Nod+, Nif-), Frank G. Hustmyer Jan 1984

Comparison Of Surface Polysaccharides Of R. Leguminosarum Anu57 (Exo-1), R. Leg. Anu57(Pbr1an) (Nod+, Nif-), And R. Leg. Anu57(Pjb5j1) (Nod+, Nif-), Frank G. Hustmyer

Masters Theses

Extracellular polysaccharides (EPS) and lipopolysaccharides (LPS) are suspected to be involved in the legume/Rhizobium symbiotic process. Polysaccharide compositions from the EPS, LPS, capsular polysaccharide (CPS), and small polysaccharide (SmPS) were compared between Rhizobium leguminosarum ANU57 (parent, Exo-1) and two mutants R. leg. ANU57(pBR1AN) (nod+, nif-) and R. leg. ANU57(pJB5J1) (nod+, nif-) both containing a Sym (symbiotic) plasmid insertion. R. leg. ANU57(pBR1AN) and R. leg. ANU57(pJB5J1) are nod+ on clover and peas, respectively. The nod+ mutants produce larger amounts of EPS and decreased amounts of LPS compared to …


A Genetic And Physiological Study Of An Arsenite Resistant, Uncoupled Mutant Of Escherichia Coli, Daniel Gordon Smiley Jan 1981

A Genetic And Physiological Study Of An Arsenite Resistant, Uncoupled Mutant Of Escherichia Coli, Daniel Gordon Smiley

Dissertations and Theses

Chromosomally determined arsenate resistance in Escherichia coli is well characterized. Little, however, is known about chromosomally determined arsenite resistance in E. coli. Accordingly, spontaneous arsenite resistant mutants were selected in a plasmid free strain of E. coli. One mutant strain was analyzed in detail, genetically and physiologically. The mutation confering arsenite resistance was shown to be a single gene mutation. Genetic mapping studies using conjugation and transduction showed that the mutation was closely linked to the ilv region of the E. coli map.


A Taxonomic Study Of Members Of The Family Entrobacteriaceae With Gas Chromatography, Madeline Ducate Apr 1974

A Taxonomic Study Of Members Of The Family Entrobacteriaceae With Gas Chromatography, Madeline Ducate

Biological Sciences Theses & Dissertations

Abstract unavailable.


Repression Of Β-Galactosidase Synthesis In Escherichia Coli By Salicylates, Joan Carlyn Olson Jan 1972

Repression Of Β-Galactosidase Synthesis In Escherichia Coli By Salicylates, Joan Carlyn Olson

Dissertations and Theses

Salicylic acid, and to a lesser extent aspirin, have been shown to repress β-galactosidase synthesis in Escherichia coli. The repression is not due to decreased inducer uptake, nor does it result from competition with inducer for repressor. Dinitrophenol does not exert similar effects on β-galactosidase synthesis. Cyclic adenosine 31, 51-monophosphate partially relieves the repression. The extent or the relief by cyclic adenosine monophosphate seems to depend on the concentration of salicylic acid. This indicates there may be direct interaction between the actions of cyclic adenosine monophosphate and salicylic acid in E. coli cells.