Mississippi River Water Quality Assessment

PROJECT OVERVIEW
Minnesota contains the headwaters of the Mississippi River, one of the largest and most important waterways in the world. A vital force in all life processes, microorganisms play a major role in the river's water quality through the biological and chemical processing they provide and as indicators of how human activity is impacting water quality. However, relatively little is actually known about as much as 99% of the microorganisms present in the river. Improved understanding of these microorganisms and the effects they have on water quality will greatly enhance efforts by federal, state, and local agencies to maintain and improve the Mississippi River's water quality. Scientists at the University of Minnesota are using this appropriation to use DNA sequencing and chemical analysis technologies to capture for the first time a more complete picture of the diversity and function of microorganisms in the river and how they influence water quality. As part of this effort, hands-on student and teacher participation and public engagement through educational exhibits will help improve public understanding of the importance of the river and water quality.

OVERALL PROJECT OUTCOME AND RESULTS
A metagenomics-based sequencing approach was utilized to characterize the bacterial community at sites along the Mississippi River in Minnesota to understand how these communities were influenced by or indicative of water quality. Results of this study revealed that the bacterial community throughout the river primarily consisted of a small number of highly abundant species that comprise a "core microbial community" that was stable both in terms of community membership and inferred functional traits. Variation in community membership and species abundances were primarily influenced by physicochemical parameters (e.g. pH and temperature) rather than spatial distance, and a reproducible community structure occurred annually toward the late summer. Furthermore, specific bacterial orders were related to chemical concentrations that co-varied with surrounding land use, suggesting that increases in abundance of these orders may be indicative of specific types of contamination throughout the river. Therefore, assessment of the total bacterial community provides more information about water quality and contamination sources than could be previously gleaned from traditional enumeration of indicator bacteria like Escherichia coli. In addition to these findings, construction of fosmid libraries to assess resistance of the bacterial community to antibiotics and heavy metals revealed that levels of resistance to both were low throughout the river. Municipal wastewater treatment was not associated with increased antibiotic resistance, but proximity to agricultural wastewater increased the frequency of resistance to the antibiotics kanamycin and ampicillin. Furthermore, the resistances to the heavy metals Cd and Cr were significantly elevated in primarily developed (urban) areas. These results indicate the influence of anthropogenic contaminants on the distribution of functional traits throughout the river. Results of this project as well as dissemination of these results are further discussed in an attached Final Report.

PROJECT RESULTS USE AND DISSEMINATION
Results of this study have been presented at national meetings of the American Society for Microbiology and submitted to peer-reviewed scientific journals for publication. In addition, exhibits have been prepared at the Bell Museum, the Science Museum of Minnesota, and Itasca State Park to inform the general community about the findings of this study. Summer workshops were also held in order to disseminate details of the methodology used in this study to high school teachers.