25 Feb Did you know that some algae can be more deadly than cobra venom?
(blog post header photo source: www.nrdc.org/harmful-algal-blooms)
Petar Davidović & Mila Djisalov
Young researchers from University of Novi Sad, BioSense Institute
Algal blooms are a frequent phenomenon in nearly all kinds of fresh water. They appear as a consequence of a rapid and excessive increase of the algal population in the aquatic environment. Global warming and eutrophication by wastewater, air pollution and fertilizers seem to lead to an increased frequency of occurrence. In many cases, these blooms are caused by Cyanobacteria (blue-green algae), which are believed to be some of the oldest organisms on Earth with fossil records dating back 3.5 billion years. This long period of evolution has enabled cyanobacteria to produce a vast array of biologically active metabolites, some of which are hazardous and quite persistent toxins (cyanotoxins), able to contaminate the respective water bodies. Under special conditions, especially when nutrient-rich waters are exposed to light, cyanobacteria can show a significantly accelerated rate of reproduction, resulting in a sudden increase in total biomass known as WATER BLOOMING.
Toxigenic (i.e. toxin-producing) Cyanobacteria present a threat to public health. Cyanotoxins are biologically active substances with lethal, sublethal and chronic effects. The toxins could be in the water without affecting aquatic life, but human exposure to the water could be harmful. Consuming the organism full of toxins, whether it has been affected or not, could be dangerous as well. To help you to understand this problem, we will tell you that some cyanotoxins produced by these algae are known to be more toxic than the deadly cobra poison!
This phenomenon may limit the use of raw water for many purposes. The purification of the contaminated water might be quite costly, which makes a continuous and large-scale treatment economically unfeasible in many cases. The key aspect of risk assessment is understanding the effects caused of the low doses of toxin which is the most common case of human intoxication. Chronic effects in humans are especially concerning due to the possibility of accidental ingestion of minute concentrations of cyanotoxins in drinking water over a long period of time.
Is there any hope of fighting this sneaky enemy?
Since these problems are hard to detect before serious harm has been done and even harder to attribute to cyanotoxins with confidence in such cases, developing novel technologies which could provide a more comprehensive view of these changes, as well as being able to detect them early on, is essential for an appropriate risk management strategy. Currently available analytical methods and immunochemical assays allow for the detection of individual cyanotoxins based on their chemical and structural properties. However, this can be done only after cyanobacteria release toxins from their cells into the environment and the methodologies themselves are often costly and time-consuming. Gene structure and function, mechanisms behind the production of these harmful agents, as well as new technologies for monitoring genetic sequence were extensively investigated in recent years. However, there is still a critical need for an efficient and reliable integrated system which would be able to collect, sample, process and analyze a water sample where a bloom has occurred. Molecular approaches based on NATs (Nucleic Acid Tests) – targeting genes involved in the biosynthesis of cyanotoxins provide an exciting option for early detection of potentially toxigenic cyanobacteria and cyanotoxins in water bodies.
Figure 2. Filamentous cyanobacterium Nostoc T11 belonging to the culture collection of Novi Sad,
University of Novi Sad
Integrating these technologies, which are portable and highly sensitive, would allow us to monitor potentially hazardous environments in real-time and identify harmful cyanobacteria by highlighting the presence of the known and characterized cyanotoxins. Developing such a universal detection system would present a significant contribution to public health and the area of water quality monitoring.