Integrative microbial contamination assessment for water quality monitoring in the Great Lakes

Abstract

<p>Recreational beaches are important local resources for attracting tourists. It is critical to keep tracking recreational water quality to prevent public health issues. Waterborne pathogens are one of the main elements that could cause recreational water related diseases. Fecal pollution is the primary source of waterborne pathogens. Therefore, it is important to quantify the amount of fecal pollution indicators that are present in the water, particular the human fecal indicator. The primary objective of this thesis is to develop an integrative microbial quality monitoring system to better understand water quality. The first part of this thesis examined the presence of a general fecal pollution indicator (<em>E. coli</em>) and a human fecal pollution indicator (human-specific <em>Bacteroidales</em>). The correlations between pollution sources and beach water quality were also studied to identify the impact of pollution sources. The results revealed the highly localized correlations at individual beaches depended on the impact from pollution sources. The weak correlations suggested some previous assumed pollution sources may only weakly impacted beach water quality.</p> <p>Because <em>E. coli</em> strains differ enormously in pathogenic potential, it is possible that environmental <em>E. coli</em> have different genetic compositions and differential gene expression in genes such as the global stress regulator <em>rpoD</em> and <em>rpoS</em>. Thus, the second part of this thesis examined genetic composition and gene expression in <em>E. coli</em> environmental strains to study how global gene expression is altered in the natural environment. The results revealed differential RpoSexpression levels in environmental <em>E. coli </em>strains, suggesting that genes regulated by <em>rpoD</em> and <em>rpoS</em> may have differential expression levels in environmental strains, compared to commonly studied laboratory strains.</p>