Researchers developed new methods for quick and accurate identification of cyanotoxins found during harmful algal blooms in a recent study funded by the Harmful Algal Bloom Research Initiative (HABRI).

An excess of nutrients, or eutrophication, in lakes and rivers has led to an increased appearance of cyanobacteria in harmful algal blooms throughout Ohio and around the world. Cyanobacteria — also known as blue-green algae — produce cyanotoxins that can impact human health and how an ecosystem functions.

Notably, the structure and toxicity of most cyanotoxin forms (also known as congeners) that are produced by cyanobacteria in Lake Erie and the Maumee River remain unknown. Such information would help reduce potential threats to Ohio residents who use waterbodies that are affected by harmful algal blooms (HABs) for recreation or as their source of drinking water.

These new methods, developed and led by Dr. Dragan Isailovic of The University of Toledo, enable quick and accurate identification of microcystins and other cyanotoxins found during HABs in northwest Ohio.

“When the Toledo water crisis happened in August of 2014, experts stated that the real toxicity of HAB-affected water depended on the concentration of individual microcystin congeners present as well as their individual toxicities,” Isailovic said.

Previous research indicated that using a combination of two analytical techniques — high-resolution mass spectrometry (HRMS) and liquid chromatography (LC) — were promising for identifying cyanotoxins. The team aimed to refine their methods to identify more toxins and enable efficient purification and toxicology studies of novel cyanotoxins.

Because cyanotoxins appear alongside other molecules, researchers collected HAB water samples, extracted the toxic molecules, separated them using liquid chromatography, and determined their structures with high-resolution mass spectrometry. Python-based software was also used to analyze the data collected. Additionally, researchers employed toxicological assays, or laboratory tests, to study the toxicities of some of the more abundant microcystin forms.

Using a modern LC-HRMS instrument and software developed for data analysis, the team identified novel varieties of microcystins as well as anabaenopeptins and cyanopeptolins — cyanopeptides that accompany microcystins during HABs in Lake Erie and the Maumee River. Currently, collaborative research is underway to isolate these cyanotoxin varieties and determine their toxicity.

“With the help of HABRI funding and through collaboration with scientists from Wayne State University, we have discovered novel varieties of these toxic cyanopeptides and developed software that has been used by our research team and others to identify them,” Isailovic said.

“After analyzing numerous aqueous samples collected by our students and collaborators at the UToledo Lake Erie Center, we have a more complete understanding of the structural diversity of cyanobacteria compounds and their degradation products (i.e., what toxins breakdown into) that can be present during a harmful algal bloom event in Lake Erie and Maumee River,” he continued.

The researchers aim to establish a database on cyanotoxin identities, distribution, and toxicity to guide decision-making related to water usage and treatment during harmful algal blooms in Ohio.

Ohio Sea Grant is supported by The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES) School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. Stone Laboratory is Ohio State’s island campus on Lake Erie and is the research, education, and outreach facility of Ohio Sea Grant and part of CFAES School of Environment and Natural Resources.