Coupled Effects of Electrical Stimulation and Antibiotics on Microbial Community in Three-Dimensional Biofilm-Electrode Reactors

Antibiotics are often misused or overused, resulting in large residue inputs in the environment. Electricity and antibiotics were regarded as potentially important factors, which impact on the microbial community during treatment of antibiotics in three-dimensional biofilm-electrode reactors (3D-BERs). Unfortunately, only a few studies have been reported yet. Four 3D-BERs and one 3D-BR (reactor with biological sludge and no voltage) were designed to assess the effect of low current, sulfamethoxazole (SMX), and tetracycline (TC) on microbial populations. The 3D-BERs achieved excellent removal efficiencies of 72.20–93.52 and 82.61–95.80% for SMX and TC, respectively. Microorganisms were classified into 58 phyla, 125 classes, 166 orders, 187 families, and 220 genera. Proteobacteria held the overwhelming predominance, followed by Bacteroidetes, Chloroflexi, Actinobacteria, Verrucomicrobia, Firmicutes, and Acidobacteria. The 3D-BERs achieved higher richness of microbial composition compared with the 3D-BR. Microbial communities and relative abundance at the phyla level were affected by low current. The microbial communities in the 3D-BERs were similar at the genus level, even with different antibiotic concentrations. However, the relative abundances and compositions of the microbial communities decreased during the treatment of antibiotics. To increase the performance of 3D-BERs, the function of microorganisms should be investigated in future studies.     

Effectiveness of Natural Compounds on DNA Damage in <Emphasis Type="Italic">Coris julis</Emphasis> (Linneaus 1758) from a Polluted Marine Area

The evaluation of DNA damage in aquatic organisms represents one of the most widely used biomarkers in the assessment and monitoring of marine pollution. Our previous research highlighted the presence of DNA damage in hepatic nuclei and blood cells of Coris julis specimens collected from Augusta harbor (Syracuse, Italy), a site highly polluted. In this work, we investigated on the ability of different natural compounds with antioxidant and immunostimulating properties, such as resveratrol (50 μM, 100 μM), amygdalin (100 μM, 200 μM), and Urtica dioica roots extract (50 and/or 100 μg/ml), in reducing DNA damage of C. julis. Blood cells were analyzed by atypical cellular comet assay. The results confirmed that Augusta specimens are the most damaged and showed that resveratrol, followed by amygdalin and U. dioica roots extract, drastically reduced DNA damage. This finding evidences the effectiveness of three natural compounds for DNA protection suggesting the possible use of feed enriched with antioxidant compounds in aquaculture practices for organisms damaged by natural and anthropic insults.     

A Greener UV and Peroxide-Based Chemical Oxygen Demand Test

Water quality assessment typically includes the determination of chemical oxygen demand (COD) by oxidation of organic matter with Cr(VI) in an acidic medium followed by digestion. Unfortunately, the required reagents are harmful and the reaction times are rather long. We investigated earlier the use of H₂O₂ as a more environmentally friendly oxidizing agent to replace the hazardous chromates. In the present study, we have furthered this possibility by incorporating the use of H₂O₂ in the presence of UV light. A protocol has been devised and tested with standards and real samples that replaces toxic Cr(VI), halves the amount of silver sulfate required, and greatly reduces the necessary reaction time, thus yielding a faster and more environmentally sound method.     

Oil concentration and fatty-acid profile of naturalized <Emphasis Type="Italic">Helianthus annuus</Emphasis> populations from Australia

Although wild annual sunflower (Helianthus annuus L.) is indigenous to North America, it has been both inadvertently and intentionally introduced into other countries, such as Australia, where it has become naturalized. Prior to this research, there were no collections of naturalized H. annuus from Australia in the USDA National Plant Germplasm System gene bank. The possibility exists that naturalized Australian populations may contain distinct traits, such as oil content and fatty-acid composition, differing from their North American progenitors due to the different environments, diseases, and insect-pest complexes. The objective of this study was to collect naturalized H. annuus populations from the five states of Australia and to analyze them for oil content and fatty-acid composition. Fifty-six populations were collected throughout the broad distributional range of this species and then analyzed for oil content and fatty-acid composition. The mean oil content of the H. annuus populations was 28%, ranging from a low of 19% to a high of 31%, similar to populations of this species in its native North American habitats. Fatty-acid profiles were also similar for North American wild populations, Australian naturalized populations, and improved cultivars. Oil concentration of hybrids can be rapidly increased to acceptable levels by backcrossing with cultivated sunflower. Based on this fact, there should be little concern about the relatively low oil content of these naturalized populations when they are used as a source of other unique traits for cultivated sunflower improvement.     

Selective effects of forest fires on the structural domains of soil humic acids as shown by dipolar dephasing <Superscript>13</Superscript>C NMR and graphical-statistical analysis of pyrolysis compounds

Purpose

Data management strategies of pyrolysis results and NMR acquisition modes were examined in humic acids (HAs) from control soils and fire-affected soils. The information supplied by dipolar dephasing (DD) ¹³C NMR spectroscopy and Curie-point pyrolysis were used to assess chemical structures hardly recognizable and measurable, or of unclear interpretation, when using ¹³C NMR under standard acquisition pulses (cross-polarization/magic angle spinning, CPMAS).

Materials and methods

The HAs were isolated from two forest soils under Pinus halepensis and Pinus sylvestris in control and burned sites affected by medium or severe-intensity wildfires. For NMR analyses, during DD acquisition conditions, a 180° ¹³C pulse was inserted to minimize phase shifts. Curie-Point pyrolysis was carried out at 510 °C for 5 s, and the pyrolysis fragments were analyzed by GC/MS. The total abundances of the major pyrolysis products were compared by an update of the classical Van Krevelen’s graphical-statistical approach, i.e., as surface density values in the space defined by the compound-specific H/C and O/C atomic ratios.

Results and discussion

The DD ¹³C NMR experiments displayed significant differences in the HA spectral profiles as regards to the standard CPMAS ¹³C NMR acquisition conditions, mainly in the chemical shift region of alkyl structures as well as for tannin- or carbohydrate-like O-alkyl structures. In fact, the comparison between DD and CPMAS solid-state NMR suggested shortening of alkyl chains and generation of carbohydrate-derived, unsaturated structures—viz. furans—which adds to the aromatic domain. Pyrolytic results showed fire-induced specific changes in HAs chemical structure and its molecular diversity. The changes were evident in the location and sizes of the different clusters of pyrolysis compounds defined by their atomic ratios.

Conclusions

The DD ¹³C NMR provided specific information on the fate of aliphatic structures and the origin of unsaturated HA structures, which could be helpful in differentiating “inherited” from “pyrogenic” aromatic structures. This is further confirmed by the analysis of the molecular assemblages of pyrolytic products, which showed accumulation of condensed polyaromatic domains in the HAs after the high-intensity fire, accompanied by a recalcitrant alkyl hydrocarbon domain. Medium-intensity fire led to aromaticity increase due to a selective accumulation of lignin-derived phenols concomitant to the depletion of aliphatic hydrocarbon constituents.

     

Trace elements bioavailability to <Emphasis Type="Italic">Triticum aestivum</Emphasis> and <Emphasis Type="Italic">Dendrobaena veneta</Emphasis> in a multielement-contaminated agricultural soil amended with drinking water treatment residues

Purpose

The in situ stabilization of multielement-contaminated agricultural soils has limited effectiveness when using common single amendments. This study examined the use of drinking water treatment residues (WTR), based on (hydr)oxides of Fe, Al, or Mn, as a cost-effective solution to optimize the immobilization of metals (Cd, Pb, Zn) and As.

Materials and methods

Trace elements (TE) bioavailability was assessed under semi-controlled conditions in a pot study cultivating winter wheat (Triticum aestivum L. cv. Tiger) until maturity. An Fe-based WTR and a Mn-based WTR, applied at rates of 0.5 and 1% (m/m), were related to effects of lime marl (LM) application. Additionally, a bioassay with earthworms (Dendrobaena veneta) was conducted. Both bioassays were compared with measurements of NH₄NO₃-soluble, diffusive gradients in thin film (DGT)-available and soil solution TE concentrations, representing well-established surrogates for mimicking the bioavailable element fractions in soil.

Results and discussion

The application of the Fe-based WTR reduced As accumulation in vegetative wheat tissues (by up to 75%) and earthworms (by up to 41%), which corresponded with the findings from soil chemical analyses and improved plant growth and earthworm body weight. However, As concentrations in cereal grains were not affected, Cd or Pb accumulation by wheat was not mitigated, and Zn uptake was enhanced. By contrast, the Mn-based WTR effected the greatest reduction in Pb uptake, and lowered Cd transfer to wheat grain (by up to 25%). Neither the NH₄NO₃-soluble nor DGT-available concentrations matched with Cd and Zn accumulation in plants or earthworms, indicating interferences due to competition for binding sites according to the biotic ligand model.

Conclusions

The results obtained in this study suggest that a bioassay with key species prior to field application should be mandatory when designing in situ stabilization options. The application of WTR to an agricultural soil strongly affected TE bioavailability to plants and earthworms. Low application rates tended to improve biomass production of biota. Higher application rates involved risks (e.g., P fixation, TE inputs), and none of the amendments tested could immobilize all targeted elements.

     

Using delayed luminescence to characterize humic acids from lake sediments

Purpose

Using the delayed luminescence (DL) method, the photoluminescent properties of humic acids (HA) extracted from lake sediments were analyzed. Delayed luminescence is a promising technique for characterizing HA and other forms of organic matter of various origins. But information is insufficient regarding both its optimal operating conditions and also those environmental factors that control the chemical constitution of samples, which affects patterns of delayed luminescence.

Materials and methods

The research material was HA from lake sediments. Humic acid extractions were carried out using the method developed by the International Humic Substances Society. Studies on excitation and recording of DL intensity of HA solutions were carried out with the use of a specially designed device for continuous recording of photo-induced luminescence. The DL was excited with a monochromatic light at multiple wavelengths.

Results and discussion

The DL intensity depended on the wavelength of the exciting light. The highest DL intensity was obtained with excitation by blue light, the lowest DL intensity was observed with excitation by red light. Statistically significant differences among DL intensity were observed in the examined humic acids. These differences may be evidence of the variable quantitative and qualitative contributions of photoluminophores to the structure of the studied HA molecules as well as their different photochemical reactivities. For the blue- and green-excited DL intensity, statistically significant positive correlations were obtained with the elemental atomic ratio O:H and CQ coefficient. For the red-excited DL intensity, statistically significant positive correlations were obtained with the C and H content and H:C, C:N atomic ratios, while negative correlations were obtained with the free radical concentration.

Conclusions

Delayed luminescence depended on the wavelength of the exciting light. The DL intensity excited by blue and green light was different than the red light-excited DL intensity. The DL depended on the primary composition of sediments and the properties and structure of HA too. The grouping of HA showed that the HA formed in organic matter-poor, silicate-rich sediments had greater DL emission than did those extracted from sediments that were enriched in organic matter.

     

Improving Estimates of Fried’s Index from Mating Competitiveness Experiments

Sterile insect technique (SIT) and incompatible insect technique (IIT) are current methods for biological control of insect populations. Critical to the successful implementation of these biocontrol programs is quantifying the competitiveness of sterile/incompatible male insects for female mates relative to wildtype males. Traditionally, entomologists measure this mating competitiveness through a quantity known as Fried’s Index. We establish that Fried’s Index is mathematically equivalent to the mating competitiveness coefficient that features in many population models used in SIT/IIT programs. Using this insight, we propose a new approach for estimating Fried’s Index from mating competitiveness experiments. We show that this approach offers greater precision and accuracy than the traditional approach that is currently used in many studies. This is demonstrated using both simulation experiments and by analysing real experimental data. To facilitate uptake of the proposed method, we also provide an R package that can be used to easily analyse data from mating competitiveness experiments.     

Photocatalytic Removal of the Antibiotic Cefotaxime on TiO<Subscript>2</Subscript> and ZnO Suspensions Under Simulated Sunlight Radiation

This study presents the main results about the removal of the antibiotic cefotaxime (CTX) under simulated sunlight radiation using heterogeneous photocatalysis with titanium dioxide (TiO₂) and zinc oxide (ZnO) in aqueous solutions. The effects of pH and catalyst initial load on pollutant removal were assessed considering the response surface methodology and a central composite circumscribed experimental design, which allowed to determine the optimized conditions that lead to a higher substrate elimination. Experimental results indicated that evaluated parameters have a significant effect on antibiotic removal in both TiO₂ and ZnO suspensions. In addition, the role of photogenerated holes, hydroxyl, and superoxide anion radicals on CTX degradation was evaluated to clarify the reaction mechanism. Finally, analysis of the dissolved organic carbon content in solutions and the antibacterial activity of treated samples showed that photocatalytic treatments were able to reduce a considerable portion of the organic matter present in the systems and its antimicrobial activity.