The issues presented in this study concern the important problem of the occurrence of cyanobacterial blooms in surface water used for water supply purposes. The objective of this study was to analyze the occurrence of cyanotoxic risk in the catchment area of the Obrzyca River, which is a source of drinking water for the inhabitants of Zielona Góra. At the points of Uście and at its tributary at Wojnowo, the river was more exposed to the blooms of toxigenic algae, whose active microcystins synthesize more here than in other places (Sadowo, Chwalim, Ostrzyce, Lubiatów). Throughout the study, conducted in 2008-12, we observed several times that the amounts of cyanobacteria exceeded 500·10 3 individuals per litre (ind.·dm , was found at Wojnowo in September 2011. The analysis of the physico-chemical water quality indicators showed that the places along the Obrzyca River where periodic cyanobacterial blooms took place were characterized by eutrophic conditions, and the total nitrogen to total phosphorus ratio (N/P) fell within the range of 10 to 16, and the water temperature exceeded 20ºC. In order to assess the toxic hazard caused by periodic cyanobacterial blooms in the catchment area of the Obrzyca River for drinking water for Zielona Góra residents, regular monitoring of the cyanobacteria and their toxins is required -especially at the points in Uście and Wojnowo as well as at the water intake at the water treatment plant (WTP) in Zawada (in central-western Poland).

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 Uście point, exceeding the provisional guideline. Extracts from Uście 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.

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.

In biomasses from 22 moulds isolated in housing buildings a Chromatographie HPLC UV/VIS analysis was carried out to assess the production of sterigmatocystin by fungal isolates. The results are discussed with respect to mycotoxic risk for people exposed to the presence ofAspergillus versicolor. This fungus is often present on building materials, but does not always produce the carcinogenic mycotoxin sterigmatocystin (ST). In this study, 19 (86%) of the 22 strains synthesized ST at detectable levels (>0.03 mg kg-1 biomass). Three of the strains (14%) were found to synthesize ST at levels exceeding 100 mg kg-1 of the air-dry mould biomass with laboratory medium. One strain proved to be highly productive and synthesized more than 500 mg kg-1 ST. Thus, it presented the highest mycotoxic danger for the dwellers of the buildings whereA. versicolor infested the walls. However, most strains are low producers of ST, with 12 of 22 isolates synthesizing less than 10 mg kg-1 biomass. Mycotoxigenic and highly productive strains that produced significant amounts of ST (>500 mg kg-1 biomass) were less frequently found, with approximately 5% of all isolates from buildings studied for ST production.

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.

The issues presented in this study concern a very important problem of the occurrence of cyanobacterial blooms in surface water used for water supply purposes. The objective of this study was to analyze the occurrence of cyanotoxic risk in the catchment area of the Obrzyca River (including Sławskie lake which is the beginning of the river), which is a source of drinking water for the inhabitants of Zielona Góra. In order to evaluate toxicity of cyanobacterial bloom it was conducted toxicological testing using aquatic invertebrates (Daphnia magna, Dugesia tigrina) and heterotrophic bacteria (Escherichia coli, Enterococcus faecalis, Pseudomonas fluorescens). Test samples were collected from May to October, 2012. The most toxic was a sample collected from Lake Sławskie on 20 th October when cyanobacteria bloom with a predominance of Microcystis aeruginosa occurred and the amount of microcystins was the largest. The methanol extract of the sample was toxic only above a concentration of 6·10 3 mg·dm -3 . The lethal concentration (48-h LC 50) for Daphnia magna was 3.09·10 3 and for Dugesia tigrina (240-h LC 50) 1.51·10 3 mg·dm -3 of microcystins (MC-LR, MC-YR and MC-RR). The same extract stimulated growth of Escherichia coli and Enterococcus faecalis cells.

Infestation of interior walls of buildings with fungal mould is a reason for health concern which is exacerbated in energy-efficient buildings that limit air circulation. Both mycological and mycotoxicological studies are needed to determine the potential health hazards to residents. In this paper, a rare case of the occurrence of Stachybotrys chartarum in an apartment building in the Lubuskie Province in Poland has been described. Isolated as the major constituent of a mixed mycobiota, its specific health relevance still needs to be carefully analyzed as its biochemical aptitude for the synthesis of mycotoxins may be expressed at different levels. Therefore, ecotoxicological tests were performed using two bioindicators: Dugesia tigrina Girard and Daphnia magna Straus. D. tigrina was used for the first time to examine the toxicity of S. chartarum. The ecotoxicological tests showed that the analyzed strain belonged to the third and fourth toxicity classes according to Liebmann’s classification. The strain of S. chartarum was moderately toxic on Potato Dextrose Agar (PDA) as a culture medium (toxicity class III), and slightly toxic on Malt Extract Agar (MEA) (toxicity class IV). Toxicity was additionally tested by instrumental analytical methods (LC-MS/MS). This method allowed for the identification of 13 metabolites (five metabolites reported for Stachybotrys and eight for unspecific metabolites). Spirocyclic drimanes were detected in considerable quantities (ng/g); a higher concentration was observed for stachybotryamide (109,000 on PDA and 62,500 on MEA) and lower for stachybotrylactam (27,100 on PDA and 46,300 on MEA). Both may explain the result observed through the bioindicators. Highly toxic compounds such as satratoxins were not found in the sample. This confirms the applicability of the two bioindicators, which also show mutual compatibility, as suitable tools to assess the toxicity of moulds.

A b s t r a c tAspergilli constitute a serious risk to the health of the inhabitants of infested rooms. Mycological analysis conducted in buildings infected with moulds in the area of the Lubuskie province (Poland) demonstrated the presence of 9 species of Aspergillus moulds: A. carbonarius A. clavatus, A. flavus, A. fumigatus, A. niger, A. ochraceus, A. terreus, A ustus and A. versicolor. The highest frequency (4 -frequently) was observed in the case of A. versicolor, while frequency 3 (fairly frequently) was characteristic of such species as A. flavus and A. niger. A. ustus was encountered with frequency 2 (individually), while frequency 1 (sporadically) referred to four species: A. carbonarius, A. clavatus, A. fumigatus and A. terreus. Because Aspergillus versicolor occurs with the highest frequency in buildings, and as a consequence of this, synthesizes toxic and carcinogenic sterigmatocystin (ST), it constitutes the greatest risk to the inhabitants of the infested premises. All species of Aspergillus present on building partitions are able to synthesise mycotoxins, are pathogens and may cause allergies.