Environmental Microbiology and Microbial Ecology Commons^™

Pseudomonas Aeruginosa-Candida Albicans Interactions: Localization And Fungal Toxicity Of A Phenazine Derivative, Jane Gibson, Arpanah Sood, Deborah A. Hogan

Dartmouth Scholarship

Phenazines are redox-active small molecules that play significant roles in the interactions between pseudomonads and diverse eukaryotes, including fungi. When Pseudomonas aeruginosa and Candida albicans were cocultured on solid medium, a red pigmentation developed that was dependent on P. aeruginosa phenazine biosynthetic genes. Through a genetic screen in combination with biochemical experiments, it was found that a P. aeruginosa-produced precursor to pyocyanin, proposed to be 5-methyl-phenazinium-1-carboxylate (5MPCA), was necessary for the formation of the red pigmentation. The 5MPCA-derived pigment was found to accumulate exclusively within fungal cells, where it retained the ability to be reversibly oxidized and reduced, and its …

New And Interesting Laboulbeniales From Brazil, Walter Rossi, Ernesto Bergonzo

Aliso: A Journal of Systematic and Floristic Botany

Two new species of Laboulbeniales are described: Laboulbenia parasyphraeae, parasitic on Parasyphraea sp. (Coleoptera, Chrysomelidae, Alticinae), and L. skelleyi, parasitic on Pselaphacus rubricatus and P. signatus (Coleoptera, Erotylidae). Other recorded species are Chaetomyces pinophili, Chitonomyces aurantiacus, Corethromyces ophitis, Dimorphomyces platensis, Dioicomyces anthici, D. cf. notoxi, Hesperomyces coccinelloides, Hydrophilomyces rhynchophorus, Laboulbenia arnaudii, L. funeralis, L. pachystoma, and L. systenae. Six ‘‘morphospecies’’ of Chitonomyces (C. appendiculatus, C. hyalinus, C. prolongatus, C. simplex, C. uncinatus, and C. cf. zonatus) parasitic on …

Microbial Nitrogen Cycling In Nevada Geothermal Springs, Mitchell G. Chaires, Jeremy A. Dodsworth, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

Hot spring habitats above maximum photosynthetic temperature (73 ºC) are not well understood with respect to nitrogen (N) cycling. Few predictions have been made, and even fewer measurements of in situ activities have been reported. Thermodynamic calculations based on in situ chemical and temperature measurements will be used to predict the occurrence of the specific N-cycling reactions. In addition, these measurements in two springs will aid in an attempt to cultivate ammonia oxidizing species.

Denitrification In Great Basin Hot Springs, Austin Mcdonald, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

Hydrogen has been proposed to fuel primary production in the Aquificae dominated hot springs of Yellowstone National Park (Spear, et al. 2005), a finding the authors generalized to all hot springs. However, clone libraries derived from Great Basin springs contain few 16S ribosomal RNA (rRNA) gene sequences from Aquificae and many from unknown microorganisms. In the same springs, alternative electron donors rival the reducing power of hydrogen. This project will try to cultivate the uncharacterized microbes of two Great Basin springs and determine which electron donors they can use.

Nitrogen is key to life. In its reduced form, ammonia, it …

Microbial Ecology Of Keane Wonder Spring, Death Valley National Park, Alexander B. Michaud, Duane P. Moser

Undergraduate Research Opportunities Program (UROP)

This research is focused on developing a better understanding of he physiological and phylogenetic diversity as well as environmental abundance of bacteria of the genus: Shewanella in selected desert ecosystems. Prior research from this laboratory has revealed that these bacteria are very abundant in sulfurand organic-rich aquatics habitats. We have selected a number of habitats for detailed investigation (cultivation, molecular ecology and relevant environmental chemistry) including the Tropicana Wash, spring in Death Valley, the lower Virgin River and possibly Big Soda Lame, Nevada.

Spatial And Temporal Patterns In The Microbial Diversity Of A Meromictic Soda Lake In Washington State, Pedro A. Dimitriu, Holly C. Pinkart, Brent M. Peyton, Melanie R. Mormile

All Faculty Scholarship for the College of the Sciences

The microbial community diversity and composition of meromictic Soap Lake were studied using culture-dependent and culture-independent approaches. The water column and sediments were sampled monthly for a year. Denaturing gradient gel electrophoresis of bacterial and archaeal 16S rRNA genes showed an increase in diversity with depth for both groups. Late-summer samples harbored the highest prokaryotic diversity, and the bacteria exhibited less seasonal variability than the archaea. Most-probable-number assays targeting anaerobic microbial guilds were performed to compare summer and fall samples. In both seasons, the anoxic samples appeared to be dominated by lactate-oxidizing sulfate-reducing prokaryotes. High numbers of lactate- and acetate-oxidizing …

Candida Albicans Tup1 Is Involved In Farnesol-Mediated Inhibition Of Filamentous-Growth Induction, Bessie W. Kebaara, Melanie L. Langford, Dhammika H. M. L. P. Navarathna, Raluca Dumitru, Kenneth W. Nickerson, Audrey L. Atkin

Kenneth Nickerson Papers

Candida albicans is a dimorphic fungus that can interconvert between yeast and filamentous forms. Its ability to regulate morphogenesis is strongly correlated with virulence. Tup1, a transcriptional repressor, and the signaling molecule farnesol are both capable of negatively regulating the yeast to filamentous conversion. Based on this overlap in function, we tested the hypothesis that the cellular response to farnesol involves, in part, the activation of Tup1. Tup1 functions with the DNA binding proteins Nrg1 and Rfg1 as a transcription regulator to repress the expression of hypha-specific genes. The tup1/tup1 and nrg1/nrg1 mutants, but not the rfg1/rfg1 mutant, failed to …

Old Acetogens, New Light, Steven L. Daniel, Harold L. Drake, Anita S. Gößner

Steven L. Daniel

Acetogens utilize the acetyl-CoA Wood-Ljungdahl pathway as a terminal electron-accepting, energy-conserving, CO2-fixing process. The decades of research to resolve the enzymology of this pathway (1) preceded studies demonstrating that acetogens not only harbor a novel CO2-fixing pathway, but are also ecologically important, and (2) overshadowed the novel microbiological discoveries of acetogens and acetogenesis. The first acetogen to be isolated, Clostridium aceticum, was reported by Klaas Tammo Wieringa in 1936, but was subsequently lost. The second acetogen to be isolated, Clostridium thermoaceticum, was isolated by Francis Ephraim Fontaine and co-workers in 1942. C. thermoaceticum became the most extensively studied acetogen and …

The Role Of Sos Boxes In Enteric Bacteriocin Regulation, Jan A.C. Vriezen Dr., Osnat Gillor Dr., Margaret A. Riley Dr.

Jan A.C. Vriezen Dr.

Bacteriocins are a large and functionally diverse family of toxins found in all major lineages of Bacteria. Colicins, those bacteriocins produced by Escherichia coli, serve as a model system for investigations of bacteriocin structure–function relationships, genetic organization, and their ecological role and evolutionary history. Colicin expression is often dependent on host regulatory pathways (such as the SOS system), is usually confined to times of stress, and results in death of the producing cells. This study investigates the role of the SOS system in mediating this unique form of toxin expression. A comparison of all the sequenced enteric bacteriocin promoters reveals …

Old Acetogens, New Light, Steven L. Daniel, Harold L. Drake, Anita S. Gößner

Faculty Research & Creative Activity

Acetogens utilize the acetyl-CoA Wood-Ljungdahl pathway as a terminal electron-accepting, energy-conserving, CO2-fixing process. The decades of research to resolve the enzymology of this pathway (1) preceded studies demonstrating that acetogens not only harbor a novel CO2-fixing pathway, but are also ecologically important, and (2) overshadowed the novel microbiological discoveries of acetogens and acetogenesis. The first acetogen to be isolated, Clostridium aceticum, was reported by Klaas Tammo Wieringa in 1936, but was subsequently lost. The second acetogen to be isolated, Clostridium thermoaceticum, was isolated by Francis Ephraim Fontaine and co-workers in 1942. C. thermoaceticum became the most extensively studied acetogen and …

Old Acetogens, New Light, Steven Daniel, Harold Drake, Anita Gößner

Faculty Research & Creative Activity

Acetogens utilize the acetyl-CoA Wood-Ljungdahl pathway as a terminal electron-accepting, energy-conserving, CO2-fixing process. The decades of research to resolve the enzymology of this pathway (1) preceded studies demonstrating that acetogens not only harbor a novel CO2-fixing pathway, but are also ecologically important, and (2) overshadowed the novel microbiological discoveries of acetogens and acetogenesis. The first acetogen to be isolated, Clostridium aceticum, was reported by Klaas Tammo Wieringa in 1936, but was subsequently lost. The second acetogen to be isolated, Clostridium thermoaceticum, was isolated by Francis Ephraim Fontaine and co-workers in 1942. C. thermoaceticum became the most extensively studied acetogen and …

Ship Ballast Tanks: How Microbes Travel The World, Fred C. Dobbs

OES Faculty Publications

As the international shipping fleet travels the oceans, it carries with it hidden cargoes of microbes. Fred C. Dobbs explores the hazards posed and what can be done to counteract them.

Gene Expression Reveals Unique Skeletal Patterning In The Limb Of The Direct-Developing Frog, Eleutherodactylus Coqui, Ryan Kerney, James Hanken

Ryan Kerney

The growing field of skeletal developmental biology provides new molecular markers for the cellular pre- cursors of cartilage and bone. These markers enable resolution of early features of skeletal development that are otherwise undetectable through conventional staining tech- niques. This study investigates mRNA distributions of skeletal regulators runx2 and sox9 along with the cartilage-dominant collagen 2a1 (col2a1) in embryonic limbs of the direct- developing anuran, Eleutherodactylus coqui. To date, distri- butions of these genes in the limb have only been examined in studies of the two primary amniote models, mouse and chicken. In E. coqui, expression of transcription factors runx2 …

Identifying The Fundamental Units Of Bacterial Diversity: A Paradigm Shift To Incorporate Ecology Into Bacterial Systematics, A. F. Koeppel, E. B. Perry, J. Sikorski, A. Warner, D. M. Ward, A. P. Rooney, E. Brambilla, N. Connor, E. Nevo, R. M. Ratcliff, Frederick M. Cohan

Frederick M. Cohan

No abstract provided.