Effects of Harmful Cyanobacteria on Drinking Water Source Quality and Ecosystems.

A seasonal plethora of cyanobacteria in the plankton community can have severe implications, not only for water ecosystems but also for the availability of treated water. The catchment of the Obrzyca River (a source of drinking water) is seasonally exposed to harmful cyanobacterial bloom. Previous studies (2008-2012; 2019) revealed that the most polluted water of the Obrzyca River was Uscie, close to the outlet of Rudno Lake (at the sampling point). Therefore, the effect on this lake was specifically examined in this study. Sampling was performed from May to September at that site and from July to September 2020 at Rudno Lake. The conducted analysis revealed a massive growth of Aphanizomenon gracile, especially in Rudno Lake. The results showed not only the distinct impact of cyanobacterial bloom on phytoplankton biodiversity but also the presence of microcystins and other cyanopeptides in both sampling points. The maximal total concentration of microcystins (dmMC-RR, MC-RR, dmMC-LR, MC-LR, MC-LY, MC-YR) equaled 57.3 µg/L and the presence of cyanopeptides (aeruginosin, anabaenopeptin) was originally determined in Rudno Lake, August 2021. The presence of these toxins was highlighted in our results for the first time. The same samples from the lake were the most toxic in biotoxicological investigations using the planarian Dugesia tigrina. The performed bioassays proved that D. tigrina is a sensitive bioindicator for cyanotoxins. The physical and chemical indicators of water quality, i.e., color, temperature, total suspended solids, and total nitrogen and phosphorus, showed a significant correlation among each other and towards cyanobacterial abundance and microcystin concentrations.

The Occurrence of Potential Harmful Cyanobacteria and Cyanotoxins in the Obrzyca River (Poland), a Source of Drinking Water.

Harmful cyanobacteria and their cyanotoxins may contaminate drinking water resources and their effective control remains challenging. The present study reports on cyanobacterial blooms and associated cyanotoxins in the Obrzyca River, a source of drinking water in Poland. The river was examined from July to October 2019 and concentrations of microcystins, anatoxin-a, and cylindrospermopsin were monitored. The toxicity of water samples was also tested using an ecotoxicological assay. All studied cyanotoxins were detected with microcystins revealing the highest levels. Maximal microcystin concentrations (3.97 µg/L) were determined in September at Uscie point, exceeding the provisional guideline. Extracts from Uscie point, where the dominant species were Dolichospermum flos-aquae (August), Microcystis aeruginosa (September), and Planktothrix agardhii (October), were toxic for Dugesia tigrina Girard. Microcystin concentrations (MC-LR and MC-RR) were positively correlated with cyanobacteria biovolume. Analysis of the chemical indicators of water quality has shown relationships between them and microcystins as well as cyanobacteria abundance.

The Efficiency of Microstrainers Filtration in the Process of Removing Phytoplankton with Special Consideration of Cyanobacteria.

The research presented in this manuscript concerns the evaluation of the effectiveness of microstrainers, which are designed to reduce the amount of plankton in treated surface water. The efficiency of microstrainer filtration analysis is very important for the proper course of the water-treatment process not only in the Water-Treatment Plant (WTP) in Zielona Góra (central western Poland) but also in other WTPs around the world. The qualitative and quantitative monitoring of the abundance of plankton including cyanobacteria during the particle-filtration process allows not only for the assessment of the potential cyanotoxic risk in surface water providing a source of drinking water, but also allows the evaluation of the action and the prevention of adverse impacts of microstrainers. Over four years of research, it was observed that the largest amount of cyanobacteria before microstrainer filtration took place in May. The dominant species was Limnothrix redeckei. The microstrainer removal of plankton and cyanobacteria was statistically significant. The quantity of removed plankton increased with its increasing content in raw water. The particle-filtration process, by reducing the amount of cyanobacteria, contributes to a decrease in intracellular microcystins.

Occurrence of the Toxin-Producing Aspergillus versicolor Tiraboschi in Residential Buildings.

In an area representative of a moderate climate zone (Lubuskie Province in Poland), mycological tests in over 270 flats demonstrated the occurrence of 82 species of moulds. Aspergillus versicolor Tiraboschi was often encountered on building partitions (frequency 4: frequently). The ability to synthesize the carcinogenic sterigmatocystin (ST) means that it poses a risk to humans and animals. Biotoxicological tests of biomasses of A. versicolor were conducted in the Microbiological and Toxicological Laboratory, using the planarians Dugesia tigrina (Girard). The obtained results of the tests covered a broad range of toxicity levels of isolated strains: from weakly toxic (100-1000 mg·L(-3)) to potently toxic (1-10 mg·L(-3)). The high-performance liquid chromatography (HPLC) physicochemical method confirmed the ability of A. versicolor strains to synthesize sterigmatocystin. All of the samples of the air-dry biomasses of the fungi contained ST in the range between 0.03 and 534.38 mg·kg(-1). In the bio-safety level (BSL) classification A. versicolor belongs to category 1. Additionally, A. versicolor is an allergenic mould.