Located in Brno, South Moravia

Head: prof. Ing. Blahoslav Maršálek, CSc.

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Research topics

• Cyanobacterial autecology, taxonomy and ecotoxicology
• Detection of cyanotoxins and estrogenic compounds
• Technology development in prevention and management of cyanobacterial water blooms and in water treatment – removal of toxic compounds
• Biocorrosion – mechanism of action and detection

Selected recent results

1/ Bioactive compounds from Schisandra chinensis – Risk for aquatic plants?

So called food supplements are used in our culture even more, than pharmaceuticals. Effects of food  supplements on the environment is less tested, the nit is in the case of a pharmaceuticals. World-round trend to use plants in wastewater treatment in the decentralised and nature-based ways arise the need to know how some food supplements affect the water treatment. Schisandrin already in the concentration 0,45mg/l inhibited the leaf numbers   total leaf area, and fresh weight of Lemna minor. The photosynthetic parameters (basal chlorophyll fluorescence, quantum yields) were inhibited by 0.9mg/L of the extract of S. chinensis. This work highlights  the fact, that no only pharmaceuticals, but also  food supplements shouls be tested on their effect on water ecosystems.

• Valíčková J., Zezulka Š., Maršálková E., Kotlík J., Maršálek B., Opatřilová R. 2023. Bioactive compounds from Schisandra chinensis – Risk for aquatic plants? Aquatic Toxicology, 254, 106365, doi: 10.1016/j.aquatox.2022.106365.

2/ Anxiety in Duckweed-Metabolism and Effect of Diazepam on Lemna minor

Diazepam is common psychopharmaceutical, of which tons are sold yearly. Commonly are as the urine part of waste water, are not removed by treatment plants and are measured in rivers, reservoirs, or even in drinking water. Effect of diazepam on the metabolism of aquatic organisms is not known and our recent experiment proved, that the molecular mode of action will be probably similar as in the case of human body – via GABA receptors, which were discovered in the plants only a few year ago. Therefore, our results can open an interesting scientific area, indicating that GABA receptors and interference with benzodiazepines are evolutionally much older than previously anticipated. This could help to answer more questions related to the reaction of aquatic organisms to micropollutants like psychopharmaceuticals.

• Lamaczová A., Malina T., Maršálková E., Odehnalová K., Opatřilová R., Přibilová P., Zezulka Š., & Maršálek B. 2022: Anxiety in Duckweed–Metabolism and Effect of Diazepam on Lemna minor. Water 14, 1 – 12. doi: 10.3390/w14091484

3/ Graphene oxide interaction with Lemna minor: Root barrier strong enough to prevent nanoblade-morphology-induced toxicity

Graphene and grapheneoxides are produced in tons and are used around the globe. We studied the toxicity of graphene oxides in past years, but the efects on aquatic plants was unknown. We found, that none of grapheneoxide caused lethal toxicity to Lemna minor. We proved, that although none of the three GOs caused lethal phytotoxicity to Lemna after 7 days, the mechanism of action was dependent on the GO’s surface oxidation.   Moreover, in this case in contrast to algae and crustaceans, the interaction did not lead to a mechanical damage. Therefore, our results showed that GO is not hazardous to Lemna minor even at very high concentrations (up to 25 mg/L), because the root barrier proved to be strong enough to prevent GO’s penetration and its consequent toxicity.

• Malina T., Lamaczová A., Maršálková E., Zbořil R. & Maršálek B. 2022: Graphene oxide interaction with Lemna minor: Root barrier strong enough to prevent nanoblade-morphology-induced toxicity. Chemosphere 291, 1 – 6. doi: 10.1016/j.chemosphere.2021.132739

4/ The environmental fate of graphene oxide in aquatic environment—Complete mitigation of its acute toxicity to planktonic and benthic crustaceans by algae
Graphene oxide (GO) as the most studied hydrophilic graphene derivative can be deployed in a broad spectrum of environmental technologies opening the issue of its ecotoxicity. Nevertheless, the information about its behaviour in the complex aquatic environment is still not sufficient. Here, we studied the interaction of three differently oxidized GO systems with planktonic and benthic crustaceans. By standard toxicity tests, we observed the importance of feeding strategy as well as the surface oxidation of GO with respect to GO’s ecotoxicity. However, to gain a clearer insight into GO’s environmental fate, we introduced a pre-treatment with algae as the most common source of food for crustaceans. Such an adjustment mimicking the conditions in real aquatic ecosystems resulted in complete mitigation of acute toxicity of GOs to all organisms and, more importantly, to the eradication of oxidative stress caused by GOs. We argue that the pre-exposition of food is a crucial factor in GO’s overall environmental fate, even though this fact has been completely neglected in recent studies. These experiments proved that GO is not a hazardous material in complex aquatic environments because its acute toxicity can be successfully mitigated through the interaction with algae even at very high concentrations (25 mg/L).

a) Representative optical microscopy images of Daphnia magna (left) and Heterocypris incongruens (right) after 24 (Daphnia) and 96 h (Heterocypris) with 25 mg/L of HO-GO. The scale bar is 200 μm. b) The Raman spectra of Daphnia magna (left) and Heterocypris incongruens (right) after 24 h incubation with 25 mg/L of HO- GO (blue), HU-GO (red), and TO-GO (green).

• Malina T., Marsalkova E., Hola K., Zboril R., Marsalek B. The environmental fate of graphene oxide in aquatic environment-Complete mitigation of its acute toxicity to planktonic and benthic crustaceans by algae. Journal of Hazardous Materials 2020, 399, doi:10.1016/j.jhazmat.2020.123027

5/ Synergistic effects of trace concentrations of hydrogen peroxide used in a novel hydrodynamic cavitation device allows for selective removal of cyanobacteria
Here, we present an improved and verified rotating hydrodynamic cavitation device (RHCD) inspired by so-called cavitation heaters. The cavitation efficiency of the device is adjustable by rotation speed and flow rate and can be modified for selective removal of cyanobacteria from water with only temporal effect on algal growth or metabolic activity. Previous hydrodynamic cavitation devices have required several cycles to achieve cyanobacterial elimination (12-200 cycles, 5-200 min of treatment), while the RHCD is capable to remove 99% of cyanobacteria after a single cycle lasting 6 s. The device efficiency at cyanobacterial removal was synergistically enhanced through the addition of trace concentrations of hydrogen peroxide (45-100 mu M H2O2), levels 10-1000 times lower than those used in previous studies. The RHCD is also capable to increase temperature, an additional advantage for potential technological applications. We discuss the potential use of this device over a broad spectrum of technological processes, and especially regarding the addition of hydrogen peroxide, ozone, or ferrates, which could open new areas in advanced oxidation technologies. It could also be used as an alternative or as a complement to sonochemical, microwave-assisted or electrochemical methods in chemical engineering processes requiring treatment of large volumes of liquids.

Microphotographic documentation of cavitation response. A) M. aeruginosa – control. B) M. aeruginosa – 96 h after cavitation at 5000 RPM and 4 µL L-1 H2O2 treatment – note intact cells but without gas vesicles. C) 96-hours after cavitation at 5000 RPM without H2O2 treatment – note disintegrated colonies but black dots inside cells indicating new gas vesicle synthesis. D) Desmodesmus quadricauda 96-hours after cavitation at 5000 RPM and 4 µL L-1 H2O2 treatment – note intact and actively growing cells.

• Marsalek, B.; Zezulka, S.; Marsalkova, E.; Pochyly, F.; Rudolf, P. Synergistic effects of trace concentrations of hydrogen peroxide used in a novel hydrodynamic cavitation device allows for selective removal of cyanobacteria. Chemical Engineering Journal 2020, 382, doi: 10.1016/j.cej.2019.122383