This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Gloeotrichia echinulata is a type of cyanobacterium that draws scrutiny because it tends to bloom in clear lakes, forming thick mats of visible green or white puffballs in otherwise clean water. Because of the slew of toxic compounds cyanobacteria can produce, blooms (historically called "blue-green algae") are of growing global concern.
Yet, a new study by researchers at Bigelow Laboratory for Ocean Sciences and Oregon State University suggests this particular species might not deserve its maligned reputation. The team assembled the first complete genomes of Gloeotrichia echinulata, comparing DNA samples from lakes on the West Coast and in the Northeast. They found no evidence of the machinery required to produce the toxins commonly associated with cyanobacteria, according to the new study recently published in Harmful Algae.
Gloeotrichia can still pose a nuisance, though: The samples possessed genes for producing geosmin, a compound that can affect the taste of water and warrant additional treatment. Yet, the researchers found striking genetic similarities across all the samples, despite the vast distances between them. That suggests this species has predictable properties, which is useful for public health and drinking water management.
"It may be producing yet-to-be-characterized toxins or molecules we don't understand," said research scientist Robin Sleith, the study's co-lead author. "But for all the toxins that science has done the hard work of characterizing, and that have the most acute human health hazards, there were no obvious pathways." Cyanobacteria blooms are increasing worldwide in response to changing conditions and can pose significant risks by altering food webs, depleting lakes of oxygen and producing toxins that are harmful to people. Gloeotrichia has become a particular frustration in the Northeast, where it has a wide distribution and often blooms—very visibly—in popular recreational lakes.
At least one prior study has also suggested that the cyanobacterium is capable of producing microcystin, one of the most prevalent cyanotoxins known to cause serious liver damage. "There's always some suspicion about cyanobacteria just because so many of them produce toxins, and there's such a huge suite of compounds you have to worry about," said senior research scientist Peter Countway, one of the study's co-authors. "Prime swimming season here in New England is August, which also happens to be when they're most abundant." Yet, while working with a sample from New Hampshire's Lake Winnipesaukee, Sleith said he just could not find the genes for producing microcystin.
That led him to connect with Theo Dreher, an emeritus professor at Oregon State University and the study's other co-lead, who was working on a study about toxin production on the West Coast. They decided to collaborate, ultimately pulling together a detailed comparative analysis with several complete and partial genomes from lakes in Maine, New Hampshire, California, Oregon and Washington. To pull together the Northeast samples, the Bigelow Laboratory team relied on Oxford Nanopore sequencing, an emerging molecular tool that can sequence long strands or fragments of DNA without sacrificing accuracy.
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