Undergraduate Honors Theses

Thesis Defended

Spring 2011

Document Type



Molecular, Cellular, & Developmental Biology

First Advisor

Norm Pace


Americans drink over 23 million gallons of bottled water every day, generating approximately 36 billion bottles annually. The false perception of the purity and cleanliness of expensive bottled water compared to cheap tap sources does not concur with scientific evidence. Many studies have demonstrated the presence of coliforms and heterotrophic bacteria in bottled water, and detected these organisms in counts greatly exceeding the contamination standards set for human consumption. While bacteria have been isolated from bottled water by classic microbiological culture-based methods, these techniques are capable of detecting only a subset of the true microbial onstituents. This study analyzes the microbial assemblages and bacterial load of bottled water from two different sources (municipal and spring) using culture-independent molecular techniques. Data collected from 16S ribosomal RNA gene sequencing and DAPI-stained cell counts demonstrate a correlation between different water sources and the unique and reproducible bacterial quality and load among individual brands. The sequences generated from bottled water samples bear identity to bacteria found in freshwater aqueous environments and humans; some sequences correlate with known pathogens.