Kátia Duarte

Toxicity and organic content characterization of olive oil mill wastewater undergoing a sequential treatment with fungi and photo-Fenton oxidation.

Olive oil mill wastewater (OOMW) is responsible for serious environmental problems. In this study, the efficiency of two treatments involving fungi and photo-Fenton oxidation, sequentially applied to OOMW was analyzed for organic compounds degradation and toxicity mitigation. The treatment with fungi (especially Pleurotus sajor caju) of diluted OOMW samples promoted a reduction of their acute toxicity to Daphnia longispina. Although this fungi species have not induced significant color reduction it was responsible for 72,91 and 77% reductions in chemical oxygen demand (COD), total phenolic and organic compound contents. After biological treatment, photo-Fenton oxidation seemed to be an interesting solution, especially for color reduction. However, the OOMWs remained highly toxic after photo-Fenton oxidation. Considering the second sequence of treatments, namely photo-Fenton oxidation followed by biological treatment, the former revealed, once more, a great potential because it can be applied to non-diluted OOMW, with significant reductions in COD (53-76%), total phenolic content (81-92%) and organic compounds content (100%). Despite fungal species still have demonstrated a high capacity for bioaccumulation of organic compounds, resulting from photo-Fenton oxidation, the biological treatment did not cause substantial benefits in terms of COD, total phenolic content and toxicity reduction.

Degradation of phenols in olive oil mill wastewater by biological, enzymatic, and photo-Fenton oxidation.

Background, aim, and scopeOlive oil mill wastewater (OOMW) environmental impacts minimization have been attempted by developing more effective processes, but no chemical or biological treatments were found to be totally effective to mitigate their impact on receiving systems. This work is the first that reports simultaneously the efficiency of three different approaches: biological treatment by two fungal species (Trametes versicolor or Pleurotus sajor caju), enzymatic treatment by laccase, and chemical treatment by photo-Fenton oxidation on phenols removal.Materials and methodsThose treatments were performed on OOMW with or without phenol supplement (p-coumaric, vanillin, guaiacol, vanillic acid, or tyrosol). OOMW samples resulted from treatments were extracted for phenols using liquid–liquid extraction and analyzed by gas chromatography coupled to mass spectrometry.ResultsTreatment with T. versicolor or P. sajor caju were able to remove between 22% and 74% and between 8% and 76% of phenols, respectively. Treatment by laccase was able to reduce 4% to 70% of phenols whereas treatment by photo-Fenton oxidation was responsible for 100% phenols reduction.DiscussionRange of phenol degradation was equivalent between T. versicolor, P. sajor caju and laccase for p-coumaric, guaiacol, caffeic acid, and tyrosol in supplemented OOMW, which enhances this enzyme role in the biological treatment promoted by these two species.ConclusionsPhenols were removed more efficiently by photo-Fenton treatment than by biological or enzymatic treatments.Recommendations and perspectivesUse of fungi, laccase, or photo-Fenton presents great potential for removing phenols from OOMW. This should be further assessed by increasing the application scale and the reactor configurations effect on the performance, besides a toxicity evaluation of treated wastewater in comparison to raw wastewater.

Biodegradation of polyethylene microplastics by the marine fungus Zalerion maritimum

Plastic yearly production has surpassed the 300milliontons mark and recycling has all but failed in constituting a viable solution for the disposal of plastic waste. As these materials continue to accumulate in the environment, namely, in rivers and oceans, in the form of macro-, meso-, micro- and nanoplastics, it becomes of the utmost urgency to find new ways to curtail this environmental threat. Multiple efforts have been made to identify and isolate microorganisms capable of utilizing synthetic polymers and recent results point towards the viability of a solution for this problem based on the biodegradation of plastics resorting to selected microbial strains. Herein, the response of the fungus Zalerion maritimum to different times of exposition to polyethylene (PE) pellets, in a minimum growth medium, was evaluated, based on the quantified mass differences in both the fungus and the microplastic pellets used. Additionally, molecular changes were assessed through attenuated total reflectance Fourier transform Infrared Spectroscopy (FTIR-ATR) and Nuclear Magnetic Resonance (NMR). Results showed that, under the tested conditions, Z. maritimum is capable of utilizing PE, resulting in the decrease, in both mass and size, of the pellets. These results indicate that this naturally occurring fungus may actively contribute to the biodegradation of microplastics, requiring minimum nutrients.

Assessment of cardiovascular disease risk using immunosensors for determination of C-reactive protein levels in serum and saliva: a pilot study

BACKGROUND Disposable immunosensors based on field effect transistors with single-walled carbon nanotubes (NTFET) were applied for the first time to clinical samples of undiluted blood serum and saliva for the determination of C-reactive protein (CRP), and validated by comparison with ELISA. RESULTS The NTFET showed comparable analytical performance with the ELISA when applied to clinical samples, which means that NTFET can be used as an alternative to ELISA. Also, a high correlation between the serum and salivary CRP levels was found with the NTFET, which means that saliva could be used based on a noninvasive sampling as an alternative fluid to blood serum. The establishment of a new range of CRP levels based on saliva was also found. CONCLUSION The monitoring of CRP in saliva samples by disposable immunosensors could be a valuable approach for the improvement of healthcare services, considering the worldwide increased incidence of cardiovascular diseases.

Green Analytical Methodologies for Preparation of Extracts and Analysis of Bioactive Compounds

Abstract In the latest decades, a growing concern toward the impact of a large consumption of solvents has been associated with the use of traditional analytical methods. In this way, environmentally friendly practices have emerged in different areas of research, including the search for bioactive compounds from marine sources. Thus, this chapter aims at reviewing strategies based on advanced analytical methodologies involving the use of alternative solvents, the decrease in the amounts of solvents consumed and samples needed, the minimization of energy consumption, negligible waste production, and technical improvements in order to follow the principles of Green Chemistry for the extraction and the analysis of bioactive compounds from marine organisms.

Removal of the organic content from a bleached kraft pulp mill effluent by a treatment with silica-alginate-fungi biocomposites

This study attempts a treatment strategy of a bleached kraft pulp mill effluent with Rhizopus oryzae or Pleurotus sajor caju encapsulated on silica-alginate (biocomposite of silica-alginate-fungi, with the purpose of reducing its potential impact in the environment. Active (alive) or inactive (death by sterilization) Rhizopus oryzae or Pleurotus sajor caju was encapsulated in alginate beads. Five beads containing active and inactive fungus were placed in a mold and filled with silica hydrogel (biocomposites). The biocomposites were added to batch reactors containing the bleached kraft pulp mill effluent. The treatment of bleached kraft pulp mill effluent by active and inactive biocomposites was performed throughout 29 days at 28°C. The efficiency of treatment was evaluated by measuring the removal of organic compounds, chemical oxygen demand and the relative absorbance ratio over time. Both fungi species showed potential for removal of organic compounds, colour and chemical oxygen demand. Maximum values of reduction in terms of colour (56%), chemical oxygen demand (65%) and organic compounds (72–79%) were attained after 29 days of treatment of bleached kraft pulp mill effluent by active Rhizopus oryzae biocomposites. The immobilization of fungi, the need for low fungal biomass, and the possibility of reutlization of the biocomposites clearly demonstrate the industrial and environmental interest in bleached kraft pulp mill effluent treatment by silica-alginate-fungi biocomposites.

A fluorescence-based optical fiber analyzer for catecholamine determination

An optical fibre (OF) analyzer for measuring catecholamines (dopamine, norepinephrine and epinephrine) in biological samples with induced fluorescence was developed. The analytical set-up included a chromatographic column for catecholamine separation and a fluorescence-based OF detection (FOF-analyzer). The detection limit of the FOF-analyser was found to be less than 0.9 pg mL−1. The proposed methodology showed an adequate analytical performance for the determination of the catecholamines in actual samples of human urine. The analytical performance of the FOF-analyzer for catecholamine determination was investigated against the high performance liquid chromatography-electrochemical detection (HPLC-ED) method. The FOF-analyzer showed lower detection limits and larger linear ranges for determination of dopamine (DA), norepinephrine (NE) and epinephrine (E) in comparison with HPLC-ED and other methodologies such as HPLC-fluorescence. These advantages combined with the compact design, small-scale instrumentation, and effective cost of analysis make this system an interesting alternative to the existing methodologies for the determination of catecholamines in clinical samples.

Sterols and fatty acid biomarkers as indicators of changes in soil microbial communities in a uranium mine area

Included in the 2nd tier of a site specific risk assessment that is being carried out in an abandoned uranium mine (Cunha Baixa uranium mine, Central Portugal), fatty acids biomarkers and sterols were analyzed to assess the impact of soil contamination with metals and radionuclides in the structure of the microbial community in seven sampling sites located at different distances from the mine. Surface soil samples were collected in those sampling sites in the four different seasons of the year. Principal component analysis (PCA) was performed on fatty acid biomarkers and sterols. Subsequently PCA scores obtained for both components were used to test the effect of sites and seasons, on soil samples collected in the Cunha Baixa uranium mine, through bi-factorial ANOVAs. Through PCA analysis, two distinct groups were set apart along the first two components. One group included sites at a great distance from the mine which were negatively correlated with higher contents of iC15:0 and iC17:0, both indicators of Gram-positive bacteria, as well as with ergosterol, cholestanol and cholesterol. The second group, in turn, was composed of the sampling sites most impacted by ore exploration, in situ leaching of poor ore, and spread of sludge from the effluent treatment pond. These sites were positively correlated with higher levels of iC16:0 (Gram-positive bacteria indicator), cyC17:0 (generally common in gram negative bacteria) and C18:0 and C17:0 biomarkers of non-specific bacteria. The profile of fatty acids obtained in the sampling sites revealed variable predominance of groups of bacteria which are a clear indication of differences in the soil microbial communities that are directly related to the environmental conditions prevailing in the uranium mine area.

Classical Methodologies for Preparation of Extracts and Fractions

Abstract Sample preparation is an important step in the whole process of analysis of bioactive compounds. For the preparation of extracts and fractions from marine organisms such as fungi, algae, bacteria, and invertebrates, there is a classical approach, which is currently the most used. After their isolation from the marine environment, the samples are subjected to an initial extraction. Since the chemical nature of the bioactive compounds in the resulting extracts is unknown, it becomes impossible to follow a general technique to separate the several classes of compounds in the extract. Therefore, the fractionation by solvent partition and the separation and purification by chromatography are two examples of the methodologies discussed for the separation of the mixture into fractions of pure bioactive compounds. Thus, this chapter focuses mainly on the classical approaches to prepare the extracts and fractions from marine organisms containing bioactive compounds with pharmaceutical and therapeutical interest.

Carbon nanotube field effect transistor biosensor for the detection of toxins in seawater

ABSTRACT Disposable field effect transistors (FET) biosensors (bio-FET) based on carbon nanotubes were fabricated for detection of domoic acid (DA), which belongs to the group of biotoxins associated with the amnesic shellfish poisoning. The analytical results obtained with the bio-FET were compared with those obtained with a traditional methodology (enzyme-linked immunosorbent assay) in order to validate the bio-FET for DA detection. Standard solutions of DA with concentrations between 10 and 500 ng L−1 were tested in order to construct the calibration curve, where five bio-FET were used for reproducibility estimation and two analytical measurements were performed for each bio-FET for repeatability estimation. Ten spiked artificial seawater samples were used to validate the bio-FET. The obtained reproducibility (0.52–1.43%), repeatability (0.57–1.27%), limit of detection (10 ng L−1) and recovery range (92.3–100.3%) reveal an adequate analytical performance of the bio-FET for the detection of DA in environmental samples such as seawater samples.