Microbiology Commons^™

Oral Microbial Burden Of Periodontal Pathogens Among Orthodontic Patients, David Jolley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Objectives

Many research studies involving orthodontic patients have a natural inclination to focus on changes in levels of cariogenic pathogens after bracket placement, and very few studies examine the role of changes of periodontal pathogens – particularly among adult patients. Interestingly, recent evidence suggests that increased levels of a specific periodontal pathogen, Fusobacterium nucleatum, may elevate risk for development of colon cancer in adults through direct pathways. Based upon this new evidence, the objective of the current study was to screen saliva samples taken from orthodontic patients to determine the prevalence of periodontal pathogens, including F. Nucleatum, T. denticola, and …

Development Of The K-State (Competence) And Mutagenesis In Stressed Bacillus Subtillis Cells, Amanda Kidman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Mutagenesis is central to the evolutionary process. We currently view evolution as a gradual process affecting all cells within a population. However, my project studied an underestimated part of the evolutionary process: mutations generated during stationary phase (caused by nutritional stress or growth arrest) within a subpopulation of cells. I used Bacillus subtilis, a bacterial model for cell growth and differentiation. Stationary-phase cultures of B. subtilis differentiate subpopulations that exhibit different survival strategies including competence, secondary metabolite production, biofilm formation, cannibalism, and endospore formation. The development of competence permits cells to uptake exogenous DNA and incorporate it into their genome. …

Comparative Genomics Of 9 Novel Paenibacillus Larvae Bacteriophages, Casey Stamereilers, Lucy Leblanc, Diane Yost, Penny S. Amy, Philippos K. Tsourkas

Life Sciences Faculty Research

American Foulbrood Disease, caused by the bacterium Paenibacillus larvae, is one of the most destructive diseases of the honeybee, Apis mellifera. Our group recently published the sequences of 9 new phages with the ability to infect and lyse P. larvae. Here, we characterize the genomes of these P. larvae phages, compare them to each other and to other sequenced P. larvae phages, and putatively identify protein function. The phage genomes are 38–45 kb in size and contain 68–86 genes, most of which appear to be unique to P. larvae phages. We classify P. larvae phages into 2 main clusters and …

Biogeochemistry Of A Saline, Alkaline, Terminal Lake Ecosystem In Transition; Walker Lake, Nevada, Katherine Lynn Willever

UNLV Theses, Dissertations, Professional Papers, and Capstones

Walker Lake is a saline, alkaline, terminal lake ecosystem located in west-central Nevada. For over one hundred years, anthropogenic streamflow diversions within the Walker River Basin have ultimately led to little or no water reaching Walker Lake, the basin’s terminus for water flow. These diversions have resulted in a >46 meter decrease in the lake surface altitude and increases in salinity and dissolved salt constituents that have caused the elimination of native fish species. This study examines how the lack of freshwater inflow has altered the physical, chemical, and microbiological structure of Walker Lake during the lake’s ongoing desiccation.

Between …

The Role Of Mfd In Stationary-Phase Oxidative Damage Repair In Bacillus Subtilis, Katelyn E. Porter

UNLV Theses, Dissertations, Professional Papers, and Capstones

Since the 1950’s it has been shown that bacterial cells accumulate mutations even in non- dividing conditions, but how this type of mutation occurs is still highly debated. In Bacillus subtilis, Mfd, a precursor of the nucleotide excision repair (NER) system, mediates the formation of mutations in stationary-phase or non-replicating cells. In growing cells, Mfd recruits repair when RNA polymerase is stalled during transcription; it then recruits proteins from NER to repair damage. Here, we examine the hypothesis that Mfd mediates the formation of mutations by interacting with cellular components that repair reactive oxygen species (ROS), a natural byproduct of …

Incomplete Denitrification In Thermus Species, Chrisabelle Mefferd

UNLV Theses, Dissertations, Professional Papers, and Capstones

Members the bacterial genus Thermus have been shown to be incomplete denitrifiers, terminating with nitrite or nitrous oxide (N2O). However, the ability to carry out denitrification and the evolution of nitrogen oxide reductase genes in Thermus remains poorly understood. This study tests the hypothesis that incomplete denitrification is common in Thermus and seeks to uncover patterns in the evolution of denitrification pathways in Thermus. Denitrification capacity was determined in a collection of 25 strains representing ten species of Thermus and phylogenetic analysis was performed to determine whether denitrification genes evolved horizontally in Thermus. No strains in this study reduced nitrate …

Microbial Contamination Of Ice At Food Establishments In Las Vegas, Nevada, Jerry Wills

UNLV Theses, Dissertations, Professional Papers, and Capstones

When food establishments make ice for consumption, it is important to use water free of pathogens and to employ hygienic practices. Freezing can reduce the number of culturable microorganisms present in water but does not eliminate them completely. Coliform bacteria are used as an indicator of water quality and are used to test for fecal contamination. The U.S. Environmental Protection Agency (EPA) establishes standards for drinking water, and has set a goal for zero total coliforms. Another commonly used tool to measure water quality is the heterotrophic plate count (HPC). The EPA limit for HPC is 500 colony forming units …

Effectiveness Of Commercially-Available Cosmetic Cleaners On Cosmetics And Cosmetic Brushes, Vanessa Ortiz

UNLV Theses, Dissertations, Professional Papers, and Capstones

The complex nature of skin contributes to the microbial population present on its surface. While normal skin flora is either beneficial or has no effect on the body, there are instances where pathogenic microorganisms are present and can cause infections. Damaged skin is more susceptible to infections from these microbes. Behavioral characteristics, such as the use of cosmetics, can affect the microbial population present on the skin. Staphylococcus aureus is the organism most commonly isolated from cosmetics, and it can be responsible for conjunctivitis, impetigo, boils, and folliculitis.

There are many ways microbial contamination of cosmetics can occur, such as …