Isolation of Bacterial Endophytes from Phalaris arundinacea and their Potential in Diclofenac and Sulfamethoxazole Degradation

Diclofenac (DCF), a non-steroidal anti-inflammatory drug (NSAID) and sulfamethoxazole (SMX), an antimicrobial agent, are in common use and can be often detected in the environment. The constructed wetland systems (CWs) are one of the technologies to remove them from the aquatic environment. The final effect of the treatment processes depends on many factors, including the interaction between plants and the plant-associated microorganisms present in the system. Bacteria living inside the plant as endophytes are exposed to secondary metabolites in the tissues. Therefore, they can possess the potential to degrade aromatic structures, including residues of pharmaceuticals. The endophytic strain MG7 identified as Microbacterium sp., obtained from root tissues of Phalaris arundinacea exposed to DCF and SMX was tested for the ability to remove 2 mg/l of SMX and DCF in monosubstrate cultures and in the presence of phenol as an additional carbon source. The MG7 strain was able to remove approximately 15% of DCF and 9% of SMX after 20 days of monosubstrate culture. However, a decrease in the optical density of the MG7 strain cultures was observed, caused by an insufficient carbon source for bacterial growth and proliferation. The adsorption of pharmaceuticals onto autoclaved cells was negligible, which confirmed that the tested strain was directly involved in the removal of DCF and SMX. In the presence of phenol as the additional carbon source, the MG7 strain was able to remove approximately 35% of DCF and 61% of SMX, while an increase in the optical density of the cultures was noted. The higher removal efficiency can be explained by adaptive mechanisms in microorganisms exposed to phenol (i.e. changes in the composition of membrane lipids) and by a co-metabolic mechanism, where non-growth substrates can be transformed by non-specific enzymes. The presence of both DCF and SMX and the influence of the supply frequency of CWs with the contaminated wastewater on the diversity of whole endophytic bacterial communities were demonstrated. The results of this study suggest the capability of the MG7 strain to degrade DCF and SMX. This finding deserves further investigations to improve wastewater treatment in CWs with the possible use of pharmaceuticals-degrading endophytes

Identification of selected microorganisms from activated sludge capable of benzothiazole and benzotriazole transformation

Benzothiazole (BT) and benzotriazole (BTA) are present in the environment - especially in urban and industrial areas, usually as anthropogenic micropollutants. BT and BTA have been found in the municipal and industrial wastewater, rivers, soil, groundwater, sediments and sludge. The origins of those substances' presence in the environment are various industry branches (food, chemical, metallurgical, electrical), households and surface runoff from industrial areas. Increasingly strict regulations on water quality and the fact that the discussed compounds are poorly biodegradable, make them a serious problem in the environment. Considering this, it is important to look for environmentally friendly and socially acceptable ways to remove BT and BTA. The aim of this study was to identify microorganisms capable of BT and BTA transformation or/and degradation in aquatic environment. Selected microorganisms were isolated from activated sludge. The identification of microorganisms capable of BT and BTA removal was possible using molecular biology techniques (PCR, DNA sequencing). Among isolated microorganisms of activated sludge are bacteria potentially capable of BT and BTA biotransformation and/or removal. The most common bacteria capable of BT and BTA transformation were Rhodococcus sp., Enterobacter sp., Arthrobacter sp. They can grow in a medium with BT and BTA as the only carbon source. Microorganisms previously adapted to the presence of the studied substances at a concentration of 10 mg/l, showed a greater rate of growth of colonies on media than microorganisms unconditioned to the presence of such compounds. Results of the biodegradation test suggest that BT was degraded to a greater extent than BTA, 98-100% and 11-19%, respectively

Solar Light-Driven Degradation of Isoprinosine – Efficiency of the Processes and Kinetic Calculations

The photocatalytic degradation of the antiviral drug Isoprinosine (inosine pranobex, IPN) by TiO2 P─25, ZnO and SnO2 was investigated in two different aquatic matrices, i.e. milli-Q-water (MQ) and tap water (TW) under solar irradiation of 500 W/m2. The changes in concentration of IPN during all experiments were monitored using HPLC at a wavelength of 260 nm, and the photocatalytic degradation of IPN followed pseudo-first-order kinetics. The highest value of the pseudo-first-order rate constant of IPN photodegradation (k) was obtained by the presence of 20 mg/l TiO2─P25, (k=0.0483 min-1) in MQ water with the value of the coefficient of determination (R2) equal to 0.9268. The study also assessed the impact of photocatalyst doses and initial IPN concentrations on the efficacy of IPN photodegradation. The results showed that IPN was resistant to degradation under only sunlight (without any photocatalysts addition), with a degradation rate of 9% after 2 hours in milli-Q water and 16% after 2 hours in tap water. However, the addition of selected photocatalysts resulted in the breakdown of the IPN molecule. TiO2-P25 was particularly promising among the tested photocatalysts. The research also discovered that IPN partially adsorbed to TiO2 particles (33% after 2 hours), ZnO particles (26% after 2 hours), and SnO2 (4% after 2 hours). Based on the findings, solar-light-driven photocatalysis could be a promising technique for the degradation of certain antiviral drugs in environmental matrices after optimizing the process

Identification of selected microorganisms from activated sludge capable of benzothiazole and benzotriazole transformation

Benzothiazole (BT) and benzotriazole (BTA) are present in the environment - especially in urban and industrial areas, usually as anthropogenic micropollutants. BT and BTA have been found in the municipal and industrial wastewater, rivers, soil, groundwater, sediments and sludge. The origins of those substances' presence in the environment are various industry branches (food, chemical, metallurgical, electrical), households and surface runoff from industrial areas. Increasingly strict regulations on water quality and the fact that the discussed compounds are poorly biodegradable, make them a serious problem in the environment. Considering this, it is important to look for environmentally friendly and socially acceptable ways to remove BT and BTA. The aim of this study was to identify microorganisms capable of BT and BTA transformation or/and degradation in aquatic environment. Selected microorganisms were isolated from activated sludge. The identification of microorganisms capable of BT and BTA removal was possible using molecular biology techniques (PCR, DNA sequencing). Among isolated microorganisms of activated sludge are bacteria potentially capable of BT and BTA biotransformation and/or removal. The most common bacteria capable of BT and BTA transformation were Rhodococcus sp., Enterobacter sp., Arthrobacter sp. They can grow in a medium with BT and BTA as the only carbon source. Microorganisms previously adapted to the presence of the studied substances at a concentration of 10 mg/l, showed a greater rate of growth of colonies on media than microorganisms unconditioned to the presence of such compounds. Results of the biodegradation test suggest that BT was degraded to a greater extent than BTA, 98-100% and 11-19%, respectively

Solar-Driven Degradation of Ciprofloxacin in the Aquatic Environment

Ciprofloxacin (CIP), a pharmaceutical compound, -occurs as a micropollutant in various types of environmental matrices including wastewater, because it is resistant to removal via conventional methods - due to its persistent characteristics. For this reason, in this work the efficiency of photodegradation CIP (2 mg L-1) in distilled water (DW) and tap water (TP) was investigated using TiO2 and ZnO at a concentration of 20 mg L-1 each. The tests were performed without and in the presence of SO42- ions (250 mg L-1) as one of main components of the aquatic, environmental matrices. Solar-driven photocatalysis using TiO2-P25 and ZnO improved the removal efficiency of CIP compared to its solar photolysis. In all cases approximately 90% removal of CIP was observed after 20 to 30 minutes, but no mineralization processes was achieved. The most efficient degradation was obtained using TiO2 at concentration of 20 mg L-1 in DW without the presence of SO42- after 5 minutes. The photodegradation rate constants estimated kt = 0.644 min-1 and kQUV = 0.249 L kJ-1. The complexity of the matrix affected the efficiency of CIP removal, favouring DW. The impact of sulfate anions also depended on the matrix: in distilled water, their impact was negative on the photocatalysis process efficiency, while in tap water, they slightly accelerated a process of CIP decomposition. Taking this into account, photocatalysis is an efficient; however, further research is necessary

Wastewater treatment plants as a reservoir of integrase and antibiotic resistance genes – An epidemiological threat to workers and environment

Conventional mechanical and biological wastewater treatment is unable to completely eliminate all pollutants, which can therefore enter surface water bodies together with treated wastewater. In addition, bioaerosols produced during wastewater treatment can pose a threat to the health of the wastewater treatment plant staff. In order to control the impact of a wastewater treatment plant (WWTP) on the surrounding environment, including its employees, samples of wastewater and water from a river which received treated wastewater were analysed in terms of their content of antibiotics and heavy metals, levels of selected physiochemical parameters, concentrations of antibiotic-resistance genes (ARGs) and genes of integrases. Furthermore, a quantitative analysis of ARGs in the metagenomic DNA from nasal and throat swabs collected from the WWPT employees was made. Both untreated and treated wastewater samples were dominated by genes of resistance to sulphonamides (sul1, sul2), MLS group of drugs (ermF, ermB) and beta-lactams (blaOXA). A significant increase in the quantities of ARGs and concentrations of antibiotics was observed in the river following the discharge of treated wastewater in comparison to their amounts in the river water upstream from the point of discharge. Moreover, a higher concentration of ARGs was detected in the DNA from swabs obtained from the wastewater treatment plant employees than from ones collected from the control group. Many statistically significant (p < 0.05) correlations between the concentration of the gene of resistance to heavy metals cnrA versus ARGs, and between the ARGs content and the concentrations of heavy metals in both wastewater and river water samples were observed. The study has demonstrated that the mechanical and biological methods of wastewater treatment are not efficient and may affect the transmission of hazardous pollutants to the aquatic environment and to the atmospheric air. It has been shown that an activated sludge bioreactor can be a potential source of the presence of multi-drug resistant microorganisms in the air, which is a health risk to persons working in WWTPs. It has also been found that an environment polluted with heavy metals is where co-selection of antibiotic resistance may occur, in the development of which integrase genes play an essential role

Towards Sustainable Wastewater Treatment: Bioindication as a Technique for Supporting Treatment Efficiency Assessment

Constructed wetlands (CWs) are a promising alternative for conventional methods of wastewater treatment. However, the biggest challenge in wastewater treatment is the improvement of the technology used so that it is possible to remove micropollutants without additional costs. The impact of wastewater treatment in CWs on toxicity towards Aliivibrio fischeri, Daphnia magna and Lemna minor was investigated. The effects of feeding regime (wastewater fed in five batches per week at a batch volume of 1 L, or twice per week at a batch volume of 2.5 L) and the presence of pharmaceuticals (diclofenac and sulfamethoxazole), as well as the presence of Miscantus giganteus plants in CW columns (twelve of the 24 columns that were planted) were analyzed. A reduction in toxicity was observed in all experimental setups. The effluents from constructed wetlands were classified as moderately toxic (average TU for A. fischeri, D. magna and L. minor was 0.9, 2.5 and 5.5, respectively). The feeding regime of 5 days of feeding/2 days of resting resulted in a positive impact on the ecotoxicological and chemical parameters of wastewater (removal of TOC, N-NH4 and pharmaceuticals). Extended exposure of Miscantus giganteus to the wastewater containing pharmaceuticals resulted in elevated activity of antioxidant enzymes (catalase and superoxide dismutase) in leaf material

Heterogeneous Photocatalysis of Metronidazole in Aquatic Samples

Metronidazole (MET) is a commonly detected contaminant in the environment. The compound is classified as poorly biodegradable and highly soluble in water. Heterogeneous photocatalysis is the most promoted water purification method due to the possibility of using sunlight and small amounts of a catalyst needed for the process. The aim of this study was to select conditions for photocatalytic removal of metronidazole from aquatic samples. The effect of catalyst type, mass, and irradiance intensity on the efficiency of metronidazole removal was determined. For this purpose, TiO2, ZnO, ZrO2, WO3, PbS, and their mixtures in a mass ratio of 1:1 were used. In this study, the transformation products formed were identified, and the mineralization degree of compound was determined. The efficiency of metronidazole removal depending on the type of catalyst was in the range of 50–95%. The highest MET conversion (95%) combined with a high degree of mineralization (70.3%) was obtained by using a mixture of 12.5 g TiO2–P25 + PbS (1:1; v/v) and running the process for 60 min at an irradiance of 1000 W m−2. Four MET degradation products were identified by untargeted analysis, formed by the rearrangement of the metronidazole and the C-C bond breaking