Laura Žorža

Landfill leachate is regarded as a significant point source of pollutants that may pose a hazard to the environment, particularly to surface and ground waters. Leachates are highly variable and heterogeneous. Our study was focused on the characterization of landfill leachates derived from young (YDS) and matured (MDS) dumpsites in terms of the abundance of micropollutants, antimicrobial resistance genes (ARG), and microbial community structure. The concentrations of poly- and perfluoroalkyl substances (PFASs) were found to be higher in MDS compared to YDS, i.e., 13.19 and 7.16 μg/L, respectively. Among pharmaceutical compounds, ibuprofen was detected at the highest concentrations, i.e., 12.54, 12.81, and 13.13 μg/L, in the leachates derived from MDS, YDS, and ponds. The distribution of bacteria, archaea, eukaryotes, and viruses in the three leachate samples was as follows: 85.15 ÷ 88.04%, 9.13 ÷ 12.29%, 2.20 ÷ 2.68%, and 0.12 ÷ 0.15%, respectively. In total, 31 distinct families of ARGs were identified, comprising a total of 80 ARGs. Incubation of P. putida MSCL650 in sterile leachate from the pond resulted in decreasing the minimum inhibitory concentrations for six antibiotics as compared to cells incubated in nutrient broth. Hydrological processes, i.e., runoff and infiltration, can increase the dissemination of ARGs.

Air pollution with formaldehyde (FA) has been an emerging concern over recent years. This study was aimed at evaluating the contribution of green wall system-derived expanded clay pellets (ECP) and biofilms to FA removal in liquid phase. The effects of four plant species on this process were compared. An inhibition of the fluorescein diacetate hydrolysis activity of biofilm-derived microorganisms was detected during the exposure to FA in both air and liquid phases, and this effect was plant-species-specific. Liquid chromatography with a UV detector was applied for the quantification of FA. The FA removal activity of ECP in the liquid phase was 76.5 mg ECP⁻¹ after a 24 h incubation in the presence of 100 mg/L FA, while the removal activity of the biofilm differed depending on the plant species used, with the highest values detected in the set with Mentha aquatica, i.e., 59.2 mg ECP⁻¹. The overall FA removal from the liquid phase during 24 h varied in the range from 63% to 82% with the initial FA concentration of 100 mg/L. Differences in biofilm formation upon ECP enrichment were detected by using confocal laser scanning microscopy. These results contribute to the understanding of air biofiltration mechanisms in hydroponic systems.

Benzalkonium chloride (BAC) is one of the most commonly used quaternary ammonium compounds in the pharmaceutical, cosmetic, and food industries. The aim of our study was to compare the physiological responses of Escherichia coli MSCL 332, Pseudomonas putida MCCL 650, and Staphylococcus epidermidis MSCL 333 on 50 mg/L BAC in rich and poor medium (100% and 5% tryptone soya broth (TSB)) in the temperature range from 8 °C to 37 °C, under static and shaking conditions. A high-throughput, 96-well microplate method was used to compare a broad range of cultivation conditions. The effect of BAC on growth, biofilm formation activity, and dehydrogenase and fluorescein diacetate hydrolysis activity was evaluated. Addition of BAC to 100% TSB inhibited biofilm formation at 37 °C by 2.4, 1.8, and 1.6 times for E. coli, P. putida, and S. epidermidis, respectively. In turn, BAC stimulated biofilm formation in E. coli in 5% TSB at 37 °C and 100% TSB at 8 °C, i.e., 1.4 and 1.3 times, respectively. Statistical optimization of broth composition with emphasis on biofilm formation and further testing under experimental conditions was performed with P. putida.

The potential of aquatic plants to accumulate Cs may be of notable importance in the environmental monitoring of radioactive wastes. This study aimed to evaluate the accumulation of Cs-133 by freshwater macrophytes Bacopa amplexicaulis, Elodea densa, Ceratophyllum submersum, and Limnobium laevigantum after a 10-day incubation period with CsCl (1–1000 μM). The partitioning of Cs and other elements, including 21 metals, such as P, B, and As, was analyzed using inductively coupled plasma mass spectrometry combined with principal component analysis (PCA). The enzymatic activity of plant crude extracts and aquatic microorganisms was characterized. The transfer factor (TF) reached the highest values of 0.13 and 0.10 for C. submersum and L. laevigantum, respectively, at 1000 μM Cs. The TFs in the other sets were below 0.1. In the presence of Cs-133, there was a significant increase in dehydrogenase activity (p < 0.05) and a decrease in the activity of the Folin–Ciocalteu assay. A three-fold decrease in culturable microorganisms was found in plants with 1000 μM Cs. PCA analysis revealed the species-specific elemental distribution in plant biomass and the aquatic phase. A negative correlation between Na, Ca (2.0–2.5, PC1) and Mg, K, and P (−2, PC1) was found. Certain enzyme groups can serve as bioindicators of Cs pollution in aquatic ecosystems.