Improving the Cultivation of Oligotroph Microorganisms from Lake Michigan
Mentor 1
Ryan Newton
Location
Union Wisconsin Room
Start Date
5-4-2019 1:30 PM
End Date
5-4-2019 3:30 PM
Description
A diverse collection of microorganisms inhabit freshwater ecosystems. These microbial communities are the primary nutrient recyclers and a major source of system productivity, which together influence water quality and ecosystem processes. However, many of the most abundant microorganisms have not been brought into culture, which limits our understanding of these microbes. This is especially true of oligotrophic (low nutrient) systems, like Lake Michigan. We hypothesize that developing a defined medium that more closely mimics the conditions of oligotrophic lakes will improve our ability to culture their inhabitants. To approach this issue, we altered the nutrient and ion concentrations of an existing defined medium, JW5, designed to culture oligotroph microbes from the ocean, to mimic Lake Michigan. We then collected and plated samples from the Milwaukee River and Lake Michigan on five occasions. On average, we recovered 407 colony forming units (CFUs) plated onto MI5 media. This result was lower, but not significantly different, from the number of CFUs obtained from the same samples plated onto 1/10 strength R2A, a commonly used but undefined medium, which was found recover 481 CFUs on average. Additionally, we scraped each plate from both media types to collect all colonies, resuspended the cells, extracted DNA, and then sequenced the V4 region of the 16S rRNA gene from the mixed colony suspensions. The sequence data suggested that at least 140 different genera formed colonies on the MI5 medium. We found the two media cultured a similar subset of bacteria; however, media type was correlated significantly to the cultured community present on each plate. Overall, our defined MI5 medium resulted in a similar CFU quantity and bacterial representation from Lake Michigan as a common undefined medium. In the future, we will work to understand how our media formulations impact the culturing of microbes relevant to oligotrophic lakes.
Improving the Cultivation of Oligotroph Microorganisms from Lake Michigan
Union Wisconsin Room
A diverse collection of microorganisms inhabit freshwater ecosystems. These microbial communities are the primary nutrient recyclers and a major source of system productivity, which together influence water quality and ecosystem processes. However, many of the most abundant microorganisms have not been brought into culture, which limits our understanding of these microbes. This is especially true of oligotrophic (low nutrient) systems, like Lake Michigan. We hypothesize that developing a defined medium that more closely mimics the conditions of oligotrophic lakes will improve our ability to culture their inhabitants. To approach this issue, we altered the nutrient and ion concentrations of an existing defined medium, JW5, designed to culture oligotroph microbes from the ocean, to mimic Lake Michigan. We then collected and plated samples from the Milwaukee River and Lake Michigan on five occasions. On average, we recovered 407 colony forming units (CFUs) plated onto MI5 media. This result was lower, but not significantly different, from the number of CFUs obtained from the same samples plated onto 1/10 strength R2A, a commonly used but undefined medium, which was found recover 481 CFUs on average. Additionally, we scraped each plate from both media types to collect all colonies, resuspended the cells, extracted DNA, and then sequenced the V4 region of the 16S rRNA gene from the mixed colony suspensions. The sequence data suggested that at least 140 different genera formed colonies on the MI5 medium. We found the two media cultured a similar subset of bacteria; however, media type was correlated significantly to the cultured community present on each plate. Overall, our defined MI5 medium resulted in a similar CFU quantity and bacterial representation from Lake Michigan as a common undefined medium. In the future, we will work to understand how our media formulations impact the culturing of microbes relevant to oligotrophic lakes.
