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The aim of the study was to determine mycoplankton species diversity in relation to the physico-chemical parameters of lake waters. The research was carried out in the summer months in 15 mesotrophic lakes and showed a high ecological significance index for Rhodotorula glutinis, Epicoccum nigrum, Fusarium sporotrichioides, and Trichophyton violaceum. Mycoplankton abundance and species diversity decreased with the depth of water, which coincided with a decrease in oxygen content and organic matter concentration. A high concentration of nitrogen compounds (total nitrogen—TN and dissolved nitrogen—DN) limited the development of mycobiota in the hypolimnion. In the metalimnion, the intensive development of organisms, especially bacteria, limited mycoplankton abundance despite perfect physical and chemical conditions for its development. Finally, mycoplankton functioned the best in slightly alkaline waters.

The aim of this study was to determine the effect of humic acid on the growth and metabolism of

Leachate from landfills is a product of complex biological and physicochemical processes occurring during waste storage. In the present study, the toxicity of landfill leachate (LL) to human and bacterial cells was investigated for better understanding of LL environmental toxicity. Studies regarding LL physicochemical properties and cytotoxicity analysis were conducted. In Escherichia coli, Pseudomonas fluorescens, Bacillus subtilis, fibroblasts and melanoma A-375 cells, cell viability assays were applied. For the determination of LL antibacterial activity, twofold dilution series of LL were prepared in the range from 50% to 0.1% (50%, 25%, 12.5%, 6.25%, 3.13%, 1.56%, 0.78%, 0.39%, 0.2%, 0.1%). Human cells viability was examined at LL concentrations of 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 5%, 10%, 15%, 20% and 30%. ROS (reactive oxygen species) content and apoptosis level were also measured in bacterial and human cells under the influence of LL. Unexpectedly obtained results indicate stimulation of bacterial viability by LL. Fibroblasts under the influence of LL showed decrease in their viability and increase in apoptosis level and A-375 melanoma cells showed an increase in relative viability and decrease in apoptosis. ROS level in bacterial cells was elevated in higher LL concentrations and decreased in lower LL concentrations. In human cells, ROS content was rather high in both tested cell lines. Presented results indicate cytotoxic potential of analyzed LL and the necessity of LL monitoring because it may pose a health hazard for exposed human populations and the whole human environment.

Seven derivatives of plant-derived hydroxybenzoic acid (HBA)—including 2,3-dihydroxybenzoic (2,3-DHB, pyrocatechuic), 2,4-dihydroxybenzoic (2,4-DHB, β-resorcylic), 2,5-dihydroxybenzoic (2,5-DHB, gentisic), 2,6-dihydroxybenzoic (2,6-DHB, γ-resorcylic acid), 3,4-dihydroxybenzoic (3,4-DHB, protocatechuic), 3,5-dihydroxybenzoic (3,5-DHB, α-resorcylic), and 3,4,5-trihydroxybenzoic (3,4,5-THB, gallic) acids—were studied for their structural and biological properties. Anti-/pro-oxidant properties were evaluated by using DPPH• (2,2-diphenyl-1-picrylhydrazyl), ABTS•+ (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric-reducing antioxidant power), CUPRAC (cupric-reducing antioxidant power), and Trolox oxidation assays. Lipophilicity was estimated by means of experimental (HPLC) and theoretical methods. The antimicrobial activity against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Salmonella enteritidis (S. enteritidis), and Candida albicans&nbsp, (C. albicans) was studied. The cytotoxicity of HBAs in MCF-7 and MDA-MB-231 cell lines was estimated. Moreover, the structure of HBAs was studied by means of experimental (FTIR, 1H, and 13C NMR) and quantum chemical DFT methods (the NBO and CHelpG charges, electrostatic potential maps, and electronic parameters based on the energy of HOMO and LUMO orbitals). The aromaticity of HBA was studied based on the calculated geometric and magnetic aromaticity indices (HOMA, Aj, BAC, I6, NICS). The biological activity of hydroxybenzoic acids was discussed in relation to their geometry, the electronic charge distribution in their molecules, their lipophilicity, and their acidity. Principal component analysis (PCA) was used in the statistical analysis of the obtained data and the discussion of the dependency between the structure and activity (SAR: structure–activity relationship) of HBAs. This work provides valuable information on the potential application of hydroxybenzoic acids as bioactive components in dietary supplements, functional foods, or even drugs.

The aim of this study was to determine the effect of humic acid on the growth and metabolism of Candida albicans, a common waterborne pathogenic yeast. At 10–20 mg/L, humic acid caused the greatest increase in biomass and compactness of proteins and monosaccharides, both in cells and in extracellular secretion of the yeast. At higher humic acid concentrations (40–80 mg/L), C. albicans cells still had higher protein levels compared to control, but showed reduced levels of metabolites and inhibited growth, and a significant increase in the activity of antioxidant enzymes, indicating a toxic effect of the humic acid. The increase in protein content in the cells of C. albicans combined with an increase in the activity of antioxidant enzymes may indicate that the studied yeast excels in conditions of high water enrichment with low availability of organic matter. This indicates that Candida albicans is capable of breaking down organic matter that other microorganisms cannot cope with, and for this reason, this yeast uses carbon sources that are not available to other microorganisms. This indicates that this fungus plays an important role in the organic carbon sphere to higher trophic levels, and is common in water polluted with organic matter.

The structure of the Zn(II) complex of 5-caffeoylquinic acid (chlorogenic acid, 5-CQA) and the type of interaction between the Zn(II) cation and the ligand were studied by means of various experimental and theoretical methods, i.e., electronic absorption spectroscopy UV/Vis, infrared spectroscopy FT-IR, elemental, thermogravimetric and density functional theory (DFT) calculations at B3LYP/6-31G(d) level. DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2&prime, azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric reducing antioxidant power), CUPRAC (cupric reducing antioxidant power) and trolox oxidation assays were applied in study of the anti-/pro-oxidant properties of Zn(II) 5-CQA and 5-CQA. The antimicrobial activity of these compounds against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Salmonella enteritidis and Candida albicans was tested. An effect of Zn(II) chelation by chlorogenic acid on the anti-/pro-oxidant and antimicrobial activities of the ligand was discussed. Moreover, the mechanism of the antioxidant properties of Zn(II) 5-CQA and 5-CQA were studied on the basis of the theoretical energy descriptors and thermochemical parameters. Zn(II) chlorogenate showed better antioxidant activity than chlorogenic acid and commonly applied natural (L-ascorbic acid) and synthetic antioxidants (butylated hydroxyanisol (BHA) and butylated hydroxytoluene (BHT)). The pro-oxidant activity of Zn(II) 5-CQA was higher than the ligand and increased with the rise of the compound concentration The type of Zn(II) coordination by the chlorogenate ligand strongly affected the antioxidant activity of the complex.

The main objective of this work was to determine the abundance and species diversity of fungi in the waters of selected rivers of Central Europe, NE Poland (Augustów Lakeland), differing in size, physical and chemical properties, and streamflow rate. The minimum abundance of fungi in the analysed rivers was recorded for a river with low concentration of organic matter (8200 CFU/mL, Czarna Hańcza River), and maximum for a strongly anthropogenically polluted river (24,800 CFU/mL, Kamienny Bród River). A total of 49 fungal species were identified based on PCR ITS-RFLP and DNA sequencing methods. However, RFLP-PCR method has proved to be sufficient to determine the species of 34 fungi. The highest taxonomic diversity was determined for the waters abundant in organic matter (Piecówka and Rospuda Rivers), and the lowest for rivers poor in organic matter (Netta and Czarna Hańcza Rivers). From the 49 identified species, 47% were aquatic hyphomycetes, and 18% were potentially pathogenic fungi mainly occurring in the waters of polluted rivers with increased organic matter concentrations. Moreover, a higher number of fungal taxa were recorded in fluvial waters distinguished by higher streamflow rate, and therefore, stronger water turbulence. The study results suggest that the most important factors influencing the structure of mycoplankton in rivers include pH of water, content of organic matter, degree of anthropogenic pollution, and streamflow rate.

This study describes summer phytoplankton communities in 27 lakes in the Suwałki Landscape Park (SLP) using in situ fluorescence methods. Low chlorophyll-aconcentrations were noted in most of the studied lakes, particularly in the deepest lakes with highest surface area. Green algae, diatoms and cryptophyta were dominant components of lake phytoplankton. Higher chlorophyll-aconcentrations in the shallow or more eutrophicated lakes were connected with an increase of cyanobacteria and cryptophyta concentrations as well as with a decrease in the share of diatoms inphytoplankton structure. Vertical distribution of phytoplankton in stratified lakes revealed the presence of deep chlorophyll layers just below the thermocline where the maximum concentrations of phytoplankton were up to 15 times higher than in the epilimnion zone. The deepest maximum concentration of phytoplankton was noted at a depth of 16.5 metres in Lake Jeglówek. In some lakes two or three significant increases of phytoplankton concentration in the vertical profile were observed, caused by intensive development of different algae groups.

The aim of the study was to examine the species diversity of mycoplankton in the profiles of eutrophic lakes with different abundance of indicator microorganisms and aerobic conditions, and to check whether there are species of mycoplankton characteristic for particular layers of the studied limnic ecosystems. It has been shown that the epilimnion and metalimnion of the studied lakes are characterized by the highest abundance of mycoplankton, while the highest species diversity of these microorganisms, expressed with the Shannon-Wiener index, occurred in the epilimnion and hypolimnion. The most important factors determining the species composition and abundance of mycoplankton in eutrophic lakes are: concentration of organic matter and oxygen dissolved in the water as well as electrolytic conductivity of the water. Candida argentea had the highest stability index in lakes where the metalimnion was characterized by well oxygenated water, whereas in lakes which were characterized by a lack of oxygen in the metalimnion, the predominant species was Candida albicans. This species seems to be a very good microbiological indicator of water quality, due to its interactions with indicator bacteria, in particular Pseudomonas aeruginosa and Escherichia coli.

Pyrazine-2-carboxylic acid (2-PC) and 3d transition metal pyrazine-2-carboxylates (2-PCA) were characterized by means of X-ray, spectroscopic (Raman, FTIR) and thermogravimetric analysis. X-ray diffraction data were collected at 100 K and the crystal structures were solved and refined. The general formula of the copper(II), manganese(II), nickel(II), zinc(II) and cobalt(II) pyrazine-2-carboxylates was [M(2-PCA)2(H2O)2] (where M is a metal). The cobalt(II), nickel(II), copper(II) and zinc(II) complexes crystallize in the space group P21/c, in the monoclinic crystal system The manganese(II) complex crystallizes in the space group F2dd in the orthorhombic crystal system. The coordination sphere around the metal cations can be described as octahedral, however in the case of the Cu(II) complex, the octahedral geometry is distorted in the axial direction, which is caused by the Jahn–Teller effect. The products of dehydration and decomposition processes of the studied compounds were determined from the TG (thermogravimetric) and DSC (differential scanning calorimetry) curves. The theoretical structures and the IR spectra of pyrazine-2-carboxylic acid and the manganese(II) complex were calculated at the B3LYP/6-311++G(d,p) level of theory. The aromaticity indices (HOMA, I6) were calculated for 2-PC and [M(2-PCA)2(H2O)2]2 on the basis of the theoretical bond lengths in the aromatic ring. The influence of the 3d-metals on the aromatic system of pyrazine-2-carboxylic acid is discussed. 2-PC acid complexes with transition 3d-metals show a very weak antimicrobial effect, as no inhibition of bacterial and fungal growth was noted up to 10 mg/mL.

The objective of this study was to determine the effects of physical and chemical water quality parameters in the Augustow Canal on the abundance and taxonomic diversity of aquatic fungi. The studies were conducted in the hydrological year 2012 along the environmentally valuable area of the Augustow Canal. The mean abundance of fungi was 2 160 ± 1840 CFU ml−1. The lowest abundances were observed in the uppermost part of the canal, and the highest abundances in the southern part. A total of 38 species were identified, including 13 potentially pathogenic fungi, which predominated in the central region of the canal, called the natural lake part. Redundancy analysis (RDA) indicated that variation in water chemistry caused significant changes to fungal species diversity. The results showed that fungal species diversity and abundance in the canal were particularly dependent on the extent of water pollution, as indicated by chloride and sulphate(VI) ions and electrolytic conductivity. Other water quality parameters that influenced the development of aquatic fungi were organic matter and algal biomass, responsible for water eutrophication. We propose that mycoplankton be considered a sensitive biological indicator of water quality.

Dissolved reactive manganese seems to be one of the parameters which determines the trophic status of limnic waters, as suggested by its strong correlations with total phosphorus, chlorophyll a , and water pH. The determination of the trophic status involved the application of reactive manganese due to its bioavailability, providing information on the actual, not just the potential (as in the case of total phosphorus or total organic carbon), threat of water eutrophication. The calculation of trophic states index (TSI) based on the reactive manganese concentration, as determined by TSI DRMn = 20.61 ln (DRMn) − 35.03, permits the rational assessment of the trophic status of lakes. Oligotrophic lakes are distinguished by concentrations of DRMn 150 μg/L. The trophic status of 25 lakes located in central Europe in north-eastern Poland was determined based on the proposed “manganese index” and verified by commonly applied indices proposed by Carlson, Kratzer and Brezonik, and Dunalska.

The objective of this study was to determine the species diversity and abundance of fungi in relation to the hydrochemical conditions, with special emphasis on the trophic status and degree of pollution of lakes. The study was conducted in 14 lakes of the Augustów Lakeland (central Europe, NE Poland) with different hydrological conditions, type of stratification and trophic status. The analyses were performed in the hydrological year 2013. In the waters of the studied lakes, the mean abundance of fungi was 5600±3600 CFU/mL. The minimum value (800 CFU/mL) was recorded for the mesotrophic Płaskie Lake, and the maximum value (14,000 CFU/mL) was recorded for the eutrophic Pobojno Lake. A total of 38 species of fungi were identified, including 11 belonging to the aquatic hyphomycetes; up to 14 species were potentially pathogenic fungi. The potentially pathogenic fungi, particularly Candida albicans and Scopulariopsis fusca, were found in lakes with increased concentrations of chloride and sulphate(VI) ions and may thus serve as indicators of the degree of water pollution. This paper illustrates that the species diversity and abundance of fungi in limnic waters depend on the concentration of organic matter, chlorophyll a concentration, and the degree of water pollution. The results suggest that aquatic fungi can be a valuable indicator of the degree of pollution and the sanitary quality of the water.

Physicochemical studies in four dystrophic lakes (Suchar Wielki, Suchar II, Suchar IV, and Wądołek) were carried out in Wigry National Park, NE Poland. Total manganese concentrations oscillated within the range of 386.6-647.5 μg Mn dm-3, while those of soluble reactive manganese, 112.5-328.2 μg Mn dm-3. Fairly high boron contents were recorded in the studied lakes, which amounted to 0.09-2.20 mg B dm-3. The increase in dissolved reactive manganese (DRMn) and decrease in dissolved boron concentration with the lake depth were observed. Almost half (47%) of the total manganese pool was composed of dissolved reactive soluble fraction (DRMn), then dissolved organic form (DOMn, 41%), whereas the particulate fraction (PMn) made up the smallest share (12%). Microbial decomposition of lake organic matter disappears and requirements of authotrophic plankton for Mn2+ decreases when the water temperature drops, thus the fraction prevails. The following regularity was recorded in all analysed dystrophic lakes: iron concentration decreases along with the depth, hence boron content can also be observed due to precipitated borates to bottom sediments, where they are accumulated.

Research carried out from 2007 to 2011 showed that a tested semi-natural water system with a diverse catchment (peat, peat-mineral and mineral) has a very varied quality of water, as evidenced by a the large range of conductivity (174–828 μS/cm) and pH (6.34–9.92). Natural lake parts of the semi-natural water system were similar to the artificial parts in terms of physico-chemical parameters, as evidenced by the lack of statistically significant differences between the water quality in both of these ecosystems. Taking into account the quality of various types of water in this semi-natural system, it can be seen that the river waters differed significantly (p 10.0 mg/L) contributed to a decline in values of those parameters. Moreover, lake waters within the tested semi-natural water system showed a “cleansing” function, because they caused a decrease in conductivity, pH or the concentration of carbon, total nitrogen, sulphate(VI) and chloride in waters of the canal.

Hydrochemical investigations focusing on different iron fractions were conducted in 2007 from January to December on two parts (regulated and restored) of the small lowland Rudnia River in north-eastern Poland. Concentrations of the total iron (TFe) in the water of the Rudnia River ranged from 582 μg dm-3 up to 3646 μg dm-3, and their elevated values are clearly the result of their complex binding with organic matter originating from the peat-mineral catchment of the river. Regardless of the season, in the upper part of the river (regulated channel) higher concentrations of all iron fractions than in the restored river section were observed. All tests on iron fractions showed a clear seasonal variability on both river channel parts. Higher TFe concentrations were typical for the regulated part of the river in autumn or winter, and lower in spring for the restored river channel section. For the whole of the investigated period and regardless of the season, particulate iron fraction (PFe) represented a higher proportion of TFe in the regulated channel than in the restored one. PFe constituted up to 60% TFe, on average, while the other two fractions about 20% of TFe each. However, dissolved reactive iron fraction (DRFe) made up a larger percentage of TFe than organic soluble fraction (DOFe) of iron within the year. The maximum percentage of DOFe fraction outside the growing season was caused by iron release from organic complexes and elevated concentrations of dissolved organic carbon (DOC) derived from wetlands.