Award Date

12-2011

Degree Type

Thesis

Degree Name

Master of Science in Biological Sciences

Department

Life Sciences

First Committee Member

Brian Hedlund, Chair

Second Committee Member

Duane Moser

Third Committee Member

Kumud Acharya

Graduate Faculty Representative

Jacimaria Batista

Number of Pages

87

Abstract

International concern over endocrine disrupting chemicals (EDCs) has become heightened in recent years as more studies reveal their persistence in the environment and their detrimental effects on wildlife. However, little is known about the role of microorganisms in the fate and transport of these compounds in surface waters. Las Vegas Wash, a stream flowing into Lake Mead and fed primarily by treated wastewater effluent, provided a unique experimental system in which to study the role microorganisms play in the dispersal of these compounds in aquatic systems. Samples were collected from the Las Vegas Wash downstream of the Las Vegas Valley's three wastewater treatment plants, in Las Vegas Bay near the confluence of the Las Vegas Wash and Lake Mead, at the Drinking Water Intake site, and at the Colorado River where it enters Lake Mead. The biodegradation potential of 27 pharmaceuticals and EDCs was examined utilizing native microorganisms in microcosms from the four water samples over a 120 day period. Chemical analysis at the end of the incubation revealed that the Las Vegas Wash site experienced the greatest removal, with 72% total mass reduction of the parent compounds. With the exception of the bacteriostatic control, the Colorado River site experienced the lowest degradation, with only 37% removal. Similarly, Biolog Ecoplate assays demonstrated that the Las Vegas Wash was able to use a considerably greater number of carbon substrates than any other site. Finally, microbial community composition analysis based on 16S rRNA gene censuses using Unifrac and LIBSHUFF statistical methods revealed the Las Vegas Wash community to be significantly distinct from other sampled locations, although all sites were similar with regard to overall diversity and richness. The results indicated that the Las Vegas Wash microbial community contained a broader metabolic potential for EDC biodegradation. This was further supported by phylogenetic analysis identifying a high number of phylotypes related to known isolates able to catabolize similar compounds.

Keywords

Endocrine disrupting chemicals – Biodegradation; Endocrine disrupting chemicals in water; Microorganisms; Nevada – Las Vegas Wash; United States – Lake Mead

Disciplines

Biodiversity | Desert Ecology | Environmental Health and Protection | Environmental Monitoring | Microbiology | Terrestrial and Aquatic Ecology

Language

English