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Date of Graduation
Master of Science (MS)
Department of Biology
Harmful algal blooms are a growing problem globally in both freshwater and marine systems. Cyanobacterial harmful algal blooms (cHABs) can have numerous environmental and economic impacts. cHABs can reduce oxygen levels in the water column, ultimately leading to the death of larger organisms, and reduce light penetration, impacting aquatic vegetation. cHABs can also release toxins into the water and efforts to prevent toxins from entering drinking water can cost cities millions of dollars in added filtration. Microcystis is a freshwater cyanobacterium that is globally distributed. While many of the abiotic factors that can impact bloom formation are known, biotic factors, such as microbial interactions within Microcystis blooms, are not as widely studied. To assess the impact of certain heterotrophic bacteria on the growth of Microcystis, heterotrophic bacteria were isolated from a Microcystis bloom on Lake Erie. The culturable microbiome of the bloom was compared to the unculturable microbiome. Five bacterial isolates were chosen to be grown with Microcystis to determine the impact of co-culture. The whole genomes of these five isolates were also sequenced with PacBio to determine if they contained any genes that might suggest interactions with Microcystis. Co-culture with Acidovorax cells had a significant impact on the growth rate of Microcystis cells. The filtrate of Enterobacter, Exiguobacterium, and Paenibacillus appeared to have a protective impact on Microcystis cells in high salt concentrations. The whole genomes of the sequenced heterotrophic bacteria contained genes that could be used in potential interaction with Microcystis. These were genes related functions such as nitrogen metabolism, iron scavenging, carbohydrate metabolism, and vitamin production. The data obtained from this research can be used to further explore interactions between Microcystis and heterotrophic bacteria and the potential mechanisms for protection provided by bacteria in environments that are not ideal for Microcystis growth.
Hoke, Alexa, "The Microcystis microbiome: Interactions with heterotrophic bacteria in the Microcystis phycosphere" (2019). Masters Theses. 637.
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