Biodegradation of pesticides using fungi species found in the aquatic environment.

Relatively limited attention has been given to the presence of fungi in the aquatic environment compared to their occurrence in other matrices. Taking advantage and recognizing the biodegradable capabilities of fungi is important, since these organisms may produce many potent enzymes capable of degrading toxic pollutants. Therefore, the aim of this study was to evaluate the potential ability of some species of filamentous fungi that occur in the aquatic environment to degrade pesticides in untreated surface water. Several laboratory-scale experiments were performed using the natural microbial population present in the aquatic environment as well as spiked fungi isolates that were found to occur in different water matrices, to test the ability of fungi to degrade several pesticides of current concern (atrazine, diuron, isoproturon and chlorfenvinphos). The results obtained in this study showed that, when spiked in sterile natural water, fungi were able to degrade chlorfenvinphos to levels below detection and unable to degrade atrazine, diuron and isoproturon. Penicillium citrinum, Aspergillus fumigatus, Aspergillus terreus and Trichoderma harzianum were found to be able to resist and degrade chlorfenvinphos. These fungi are therefore expected to play an important role in the degradation of this and other pollutants present in the aquatic environment.

Occurrence and analysis of endocrine-disrupting compounds in a water supply system.

This paper presents the study of the occurrence of 10 endocrine-disrupting compounds (EDCs) in 60 water samples using a method for simultaneous quantification and confirmation of the presence of these emerging compounds, using ultra-performance liquid chromatography with electrospray ionization and tandem mass spectrometry (UPLC-ESI-MS/MS). All samples were previously extracted by solid-phase extraction (SPE). Several natural and synthetic hormones (17-ß-estradiol, ethinylestradiol, estriol, estrone, progesterone, mestranol, and diethylstilbestrol) and some industrial products (4-n-nonylphenol, 4-tert-octylphenol, and bisphenol A) were chosen for this survey. The analytical limits were calculated for each compound and were used in the identification and quantification of these target compounds in EPAL's water supply system. In this study, several samples were taken from the main intakes of water (surface and groundwater) used for production of water for human consumption and from different sampling points of the drinking water distribution system (piping, nets, and reservoirs). Some target compounds, such as estriol, 4-tert-octylphenol, mestranol, and nonylphenol, were found in trace amounts in several water samples. However, the studied endocrine-disrupting appeared in very low concentrations when compared with the assessed analytical limits.

New insights concerning the occurrence of fungi in water sources and their potential pathogenicity.

Fungi are known to occur ubiquitously in the environment. In the past years, the occurrence of filamentous fungi in the aquatic environment has been a subject of growing interest. This study describes the occurrence of various fungal genera in different drinking water sources being Penicillium and Trichoderma the most representative ones (30% and 17%, respectively). Also, 24 fungal species that have not been previously described in the aquatic environment are reported in this study, being once again the major species from the Penicillium genera. This study therefore contributes to the knowledge on the richness of fungi diversity in water. 68% of the described species were found to be able to grow at 30 °C but only Aspergillus fumigatus, Aspergillus viridinutans and Cunninghamella bertholletiae were able to grow at the higher temperature tested (42 °C). 66% of the species that were able to grow at 30 °C have spore sizes below 5 µm which enables them to cause breathing infections. These were therefore identified as potential pathogenic species.

Free chlorine inactivation of fungi in drinking water sources.

The effectiveness of free chlorine for the inactivation of fungi present in settled surface water was tested. In addition, free chlorine inactivation rate constants of Cladosporium tenuissimum, Cladosporium cladosporioides, Phoma glomerata, Aspergillus terreus, Aspergillus fumigatus, Penicillium griseofulvum, and Penicillium citrinum that were found to occur in different source waters were determined in different water matrices (laboratory grade water and settled water). The effect of using different disinfectant concentrations (1 and 3 mg/l), temperatures (21 and 4 °C), and pH levels (6 and 7) was addressed. The sensitivity degree of different fungi isolates to chlorine disinfection varied among different genera with some species showing a higher resistance to disinfection and others expected to be more prone to protection from inactivation by the water matrix components. When the disinfection efficiency measured in terms of the chlorine concentration and contact time (Ct) values needed to achieve 99% inactivation were compared with the Ct values reported as being able to achieve the same degree of inactivation of other microorganisms, fungi were found to be more resistant to chlorine inactivation than bacteria and viruses and less resistant than Cryptosporidium oocysts.

Photodegradation kinetics and transformation products of ketoprofen, diclofenac and atenolol in pure water and treated wastewater.

Pharmaceutical compounds such as ketoprofen, diclofenac and atenolol are frequently detected at relatively high concentrations in secondary effluents from wastewater treatment plants. Therefore, it is important to assess their transformation kinetics and intermediates in subsequent disinfection processes, such as direct ultraviolet (UV) irradiation. The photodegradation kinetics of these compounds using a medium pressure (MP) lamp was assessed in pure water, as well as in filtered and unfiltered treated wastewater. Ketoprofen had the highest time- and fluence-based rate constants in all experiments, whereas atenolol had the lowest values, which is consistent with the corresponding decadic molar absorption coefficient and quantum yield. The fluence-based rate constants of all compounds were evaluated in filtered and unfiltered wastewater matrices as well as in pure water. Furthermore, transformation products of ketoprofen, diclofenac and atenolol were identified and monitored throughout the irradiation experiments, and photodegradation pathways were proposed for each compound. This enabled the identification of persistent transformation products, which are potentially discharged from WWTP disinfection works employing UV photolysis.

Occurrence and low pressure ultraviolet inactivation of yeasts in real water sources.

Low pressure ultraviolet photolysis proved to be an efficient treatment to achieve inactivation of different yeast species (Candida sp., Cryptococcus carnescens, Metschnikowia viticola/Candida kofuensis, Rhodosporidium babjevae, Rhodotorula minuta, and Rhodotorula mucilaginosa) isolated from water sources with very different compositions. The sensitivity degree of various yeast isolates to UV treatment varied among different genera. Species isolated from surface water gained additional photoprotective resistance as a defence mechanism to be able to survive under constant sunlight conditions compared to the groundwater isolates. Yeasts were found to be more resistant to UV treatment than E. coli, Cryptosporidium, and Giardia.

Direct photolysis of polycyclic aromatic hydrocarbons in drinking water sources.

The widely used low pressure lamps were tested in terms of their efficiency to degrade polycyclic aromatic hydrocarbons listed as priority pollutants by the European Water Framework Directive and the U.S. Environmental Protection Agency, in water matrices with very different compositions (laboratory grade water, groundwater, and surface water). Using a UV fluence of 1500 mJ/cm(2), anthracene and benzo(a)pyrene were efficiently degraded, with much higher percent removals obtained when present in groundwater (83-93%) compared to surface water (36-48%). The removal percentages obtained for fluoranthene were lower and ranged from 13 to 54% in the different water matrices tested. Several parameters that influence the direct photolysis of polycyclic aromatic hydrocarbons were determined and their photolysis by-products were identified by mass spectrometry. The formation of photolysis by-products was found to be highly dependent on the source waters tested.

Assessment of the presence and dynamics of fungi in drinking water sources using cultural and molecular methods.

A comparison of different isolation techniques and culture media for detection of filamentous fungi and yeasts in the aquatic environment revealed that the use of membrane filtration with the media dichloran rose bengal chloramphenicol (DRBC) optimized fungi detection in terms of abundance and variety in three untreated water sources with very different characteristics (surface water, spring water, and groundwater). The diversity of the fungi population captured by direct DNA extraction of fungi collected by membrane filtration was compared with the isolates obtained after selective growth using different culture media through amplification of the internal transcribed spacer gene and denaturing gradient gel electrophoresis (DGGE). The Czapek-Dox agar, Sabouraud dextrose agar, and DRBC media showed closer similarities to those obtained by the uncultured biomass for the different water sources. Based on these data and the best enumeration results, DRBC is recommended for the assessment of fungi in water sources using culture-based methods. DGGE was also used to monitor temporal variations in the fungal population structure and showed that each water matrix possessed a distinct population profile as well as that changes in the fungal community can be expected in the different matrices throughout the year.

Solid-phase extraction and gas chromatography-tandem mass spectrometry method for the simultaneous determination of several pesticides in water.

Contamination of surface and groundwater sources with pesticide residues has been of great concern for a long time and it is a major challenge for the preservation and sustainability of the environment. In order to accomplish the requirements of the European Directive 98/83/EC, we developed and validated an analytical method based on the combination of gas chromatography and tandem quadrupole mass spectrometry (GC-MS/MS) using solid-phase extraction as sample preparation. In this work nine pesticides were studied: molinate, simazine, atrazine, terbuthylazine, diazinon, alachlor, metalaxyl, metolachlor and pendimethalin. In order to get the best sensitivity and selectivity for each pesticide, several parameters of the tandem mass spectrometry were optimized using the MRM mode. Good linearity of the detector response was found for all pesticides at concentrations within the tested working range, with linear determination coefficients higher than 0.9988. Recoveries studies in several matrices with different fortification levels were performed, with recoveries between 77 and 115% with RSD lower than 9.5%. The MQLs obtained for these compounds were between 0.013 microg L(-1) and 0.022 microg L(-1), which were much lower than the maximum level established by the European legislation.

Occurrence of filamentous fungi and yeasts in three different drinking water sources.

In order to determine the occurrence of fungi in different drinking water sources and capture variability in terms of matrix composition and seasonal effects, surface water, spring water, and groundwater samples were collected in numerous sampling events. The occurrence and significance of fungi detected in the different water sources are reported and discussed in terms of colony-forming units per millilitre and by the identification of the most frequently detected isolates, at the species level, based on morphology and other phenotypic characters. All the samples were also analyzed in terms of total coliforms and Escherichia coli that are widely monitored bacteria considered as microbiology indicators of water quality. All the groundwater samples showed significantly lower levels of total coliforms, E. coli, and fungi compared to the surface and spring water samples. No significant correlations were found between the levels of fungi detected in all the matrices and the physico-chemical parameters and bacteria regularly monitored by drinking water utilities. Fifty-two fungi isolates were identified in this study, most of which have never been described to occur in water sources. The results obtained show that fungi occur widely in drinking water sources and that further studies should be conducted to address their biodegradation potential as well as if the drinking water treatment processes currently used are effective in removing these organisms and the potential secondary metabolites produced.