Harmful algal blooms (HABs) occurrences in inland surface waters are increasing worldwide, mainly due to climate change and nutrient overload. Especially in the state of Iowa, high nutrient runoff from Iowa farmlands has resulted in an increasing number of HAB-related beach closure reports over the past ten years. Cyanobacteria found in HABs can produce different toxins that have become a major concern for human and animal health risks. Microcystin-LR (MC-LR) is a commonly produced cyanotoxin during HABs and often used as the representative type of cyanotoxins. For the past several decades, bacterial degradation has been highlighted as a safe and effective way of removing MC-LR. However, there is limited understanding of the presence of these MC-LR-degrading bacterial strains in the US and particularly in the Midwest. In this study, water and sediment samples were taken from a recreational lake in Iowa (Green Valley Lake) that has historically been impacted by algal blooms. From these samples, MC-degrading strains were isolated and identified. One of the isolates (Sphingopyxis sp.) was capable of removing over 90% of MC-LR within 12 hours with no lag period in the biodegradation kinetics. Another isolate (Delftia sp.) was able to remove 90% of MC-LR in 7 days with a 3-day lag period. Both of the isolates have the mlrA gene, which is known as the gene that encodes the MlrA enzyme that linearizes MC-LR, the first step of MC-LR degradation. To understand the spatial/temporal distribution and abundance of the isolated MC-degrading bacteria as well as mlrA in Iowa lakes, DNA samples were taken from weekly water samples of 36 Iowa recreational lakes during the summer of 2018. Screening of the presence of these isolated degrader strains through 16S gene amplicon MiSeq analysis and the mlrA gene via quantitative PCR are currently underway.

Isolation and characterization of microcystin-degrading bacteria from Iowa recreational lakes

2019 Fall National Meeting

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