Microbial Diversity of the Calumet Wetlands

swingleyWesley Swingley
Assistant Professor
Department of Biological Sciences




Project Description: The Calumet wetlands are an 80-square kilometer region southeast of Chicago, IL, encompassing Lake Calumet, the Calumet Canal, and portions of the Grand Calumet and Little Calumet Rivers, which drain into Lake Michigan. The first industry, whose remnants and waste dumpsites are most evident in the Calumet wetlands, was iron and steel manufacturing. Across 100 years of industry operation, the wetlands were infilled with steel slags that contain as much as 50% metallic iron, manganese, and other steel additives: chromium, copper, titanium, molybdenum, vanadium, lead, and zinc--varying in composition within meters of each other. Subsequent long-term weathering of calcium silicates has formed a calcium hydroxide buffered groundwater pH reaching values up to 13.3, six orders of magnitude more alkaline than neutral. Alkalitolerant and alkaliphilic microorganisms have been described from a variety of alkaline environments; however the environmental adaptation and metabolism of alkaline organisms are not as well described as those in very low pH environments (typically acid-mine drainages and the like). Thus far only a single bacterial analysis of Calumet waters has been reported, showing a relatively low-diversity alkaliphilic community (Roadcap et al., 2006). Summer REU participants would be involved in my lab’s multidirectional efforts to describe the alkaliphilic and heavy-metal tolerant communities at Calumet through culturing, DNA isolation and sequencing, and subsequent taxonomic, metabolic, and evolutionary reconstruction using bioinformatics techniques.

Through coordinated analysis with Melissa Lenczewski in Geology, REU participants will have the opportunity to develop their project, literally from the ground up, by visiting the Calumet wetlands for sample collection. Simultaneous geochemical analysis from Dr. Lenczewski’s group will provide an environmental context (pH, temperature, salinity, etc.) for all samples taken. Back in the lab, REU students will assist in developing culturing medium and conditions to promote the growth of bacteria and archaea in their samples. Culturing will be aided by concurrent DNA isolation and sequence analysis, which will provide clues as to the expected microbial community members and their preferred growth conditions. Summer REU participants will also have the opportunity to cooperate with other members of my lab in analyzing whole-community environmental genome and transcript (messenger RNA) sequence sets (metagenomes and metatranscriptomes, respectively). These datasets represent the forefront in sequencing and bioinformatics of microbial communities that provide a wealth of information beyond the traditional limitation in merely identifying community members. The students will learn novel, contemporary techniques for the identification and quantification of individual community members, reconstruction of metabolic profiles, and comparison of metabolic activity between sites or in response to changing environmental conditions.

It is my hope that REU participants joining my group will gain a greater appreciation for the impact of industry on natural ecosystems and the role microorganisms play in filling niches within such toxic wastelands. Analysis of microbial metabolism and growth characteristics will inform not only the students, but the scientific community as a whole about the role of alkaliphilic organisms in adapting to or changing their extreme environment.