A new study led by researchers from Bigelow Laboratory for Ocean Sciences and Oregon State University has found that Gloeotrichia echinulata, a type of cyanobacterium that commonly blooms in clear lakes, may not produce the most dangerous toxins typically associated with cyanobacteria. Published in the journal Harmful Algae, the study is the first to assemble complete genomes of Gloeotrichia echinulata from lakes across the West Coast and the Northeast. The researchers found no genetic evidence of the pathways responsible for producing major cyanobacterial toxins. However, the samples did contain genes that produce geosmin, a compound that can affect the taste of water and may require additional treatment to remove. Despite the geographic diversity of the samples, the study found striking genetic similarities across all the Gloeotrichia echinulata strains analyzed. This consistency suggests that the species has predictable biological traits, which could be valuable for managing public health and drinking water safety. Robin Sleith, a research scientist and co-lead author of the study, noted that while Gloeotrichia may produce unknown toxins or molecules, it lacks the genetic blueprints for the most hazardous toxins currently known to science. Cyanobacteria blooms are becoming more frequent worldwide due to environmental changes, and they can disrupt ecosystems by depleting oxygen and producing harmful toxins. Gloeotrichia has been a growing concern in the Northeast, where it is widespread and often blooms in popular recreational lakes. A previous study suggested that Gloeotrichia might produce microcystin, a toxin known to cause serious liver damage. However, Sleith found no genetic evidence of microcystin production in samples from New Hampshire’s Lake Winnipesaukee, prompting a collaboration with Theo Dreher, an emeritus professor at Oregon State University, to further investigate the species' toxin production. To analyze the genomes of Gloeotrichia, the Bigelow Laboratory team used Oxford Nanopore sequencing, a cutting-edge technique that allowed them to examine the genetic makeup of the samples in detail. In addition to geosmin-producing genes, the researchers found genes that enable Gloeotrichia to grow on top of lake sediment, offering insight into how the species can thrive in low-nutrient environments. The study highlights the power of modern molecular techniques in understanding cyanobacterial biology and their ecological roles. While the findings suggest that Gloeotrichia may not be as dangerous as previously thought, the researchers caution that it can bloom alongside other cyanobacteria that do produce toxins. Some toxin-producing strains may have been missed in this study, underscoring the need for continued monitoring of lakes, especially those used for drinking water or recreation. Sleith emphasized that understanding the full range of species present in these blooms and their associated risks is essential, and that ongoing research using molecular tools can help address these questions more effectively.