Passive-Sampler-Based Bioavailability Assessment of PCB Congeners Associated with Aroclor-Containing Paint Chips in the Presence of Sediment

This is the first investigation of the bioavailability of PCBs associated with paint chips (PC) dispersed in sediment. Bioavailability of PCB-containing PC in sediment was measured using ex situ polyethylene passive samplers (PS) and compared to that of PCBs from field-collected sediments. PC were mixed in freshwater sediment from a relatively uncontaminated site with no known PCB contamination sources and from a contaminated site with non-paint PCB sources. PC < 0.045 mm generated concentrations in the PS over one order of magnitude higher than coarser chips. The bioavailable fraction was represented by the polymer-sediment accumulation factor (PSAF), defined as the ratio of the PCB concentrations in the PS and organic carbon normalized sediment. The PSAF was similar for both field sediments. The PSAFs for the field sediments were ~ 50–60 and ~ 5 times higher than for the relatively uncontaminated sediment amended with PC for the size fractions 0.25–0.3 mm and < 0.045 mm, respectively. These results indicate much lower bioavailability for PCBs associated with PC compared to PCBs associated with field-collected sediment. Such information is essential for risk assessment and remediation decision-making for sites where contamination from non-paint PCBs sources is co-located with PCB PC.

Biochar Amendment Reduces the Availability of Pb in the Soil and Its Uptake in Lettuce

The aim of this study was to investigate the ability of biochar amendment to reduce the availability of Pb in the soil and its uptake in lettuce (Lactuca sativa L. var. adela). Seedlings of lettuce were cultivated in Pb-contaminated soils, both with and without 5% biochar (w/w), as well as in a simplified soilless system (hydroponics) at the ecologically relevant Pb concentration of 100 µM, both with and without 1% biochar. Soils amended with biochar resulted in a ca. 50% reduction of the extractable (bioavailable) fraction of Pb, limiting the accumulation of this toxic element in the leaves of lettuce by ca. 50%. A similar behavior was observed for lettuce plants grown hydroponically, even with a much higher reduction of Pb uptake (ca. 80%). Increased cation exchange capacity and pH were likely the main factors limiting the bioavailability of Pb in the soil. Complexation with functional groups and precipitation/co-precipitation both on the biochar surface and in soil aggregates were likely the main mechanisms immobilizing this element.

Determination of the Elements Composition in Sempervivum tectorum L. from Bulgaria

Sempervivum tectorum L. is an evergreen plant with fleshy blue-green leaves forming a rosette. The plant is well-known in alternative medicine and has been used for thousands of years. Traditionally for medicinal purposes, the plant is used as a juice obtained by simple squeezing of fresh plants leaves. The total content of Ca, K, Na, Mg, Mn, Fe, Zn, Cu, Co, Al, V, Cr, Ni, Mo, Ba, Pb, Cd, Hg, As, and Tl in plant leaves of Sempervivum tectorum L. sampled from different habitats in Bulgaria was determined after microwave digestion and measurements by inductively coupled plasma mass spectrometry and flame atomic absorption spectrometry. Furthermore, the bioavailable fraction of essential elements Ca, Mg, Fe, Mn, and Zn was defined after extraction with a hydrochloric acid solution, mimicking stomach juice. The total element content showed a high bioavailability of essential human health elements, such as Ca, Mg, Fe, and Zn. Additionally, essential and toxic elements concentrations were quantified in a fresh juice, obtained by squeezing from plant leaves, as most frequently used in folk medicine. The results obtained demonstrated high concentrations of K, Mg, Ca, Zn, and Cu, which could be accepted as an explanation and a further confirmation of the anti-inflammatory action of this plant.

Toxic Elements in Soil and Rice in Ecuador

The concentration of trace toxic metals (Cr, Zn, As, Pb, Cd, Cu, and Ni) in soil and rice plants, including the stems, leaves, and grain, from the main rice-producing provinces in Ecuador, was determined. Additionally, the soils were analyzed to determine their properties, composition, total content, bioavailable fraction, and geochemical fractions of toxic elements. Approximately 30% of soil samples in the case of Cr and Cu and 10% of samples in the case of Ni exceeded the legal thresholds for Ecuador. Moreover, for Cr and Cu, approximately 4% and 13% of samples, respectively, exceeded the threshold value of 100 mg kg−1 proposed for these two elements in several international regulations. Concentrations of As, Pb, and Cd in the soils were below the threshold values established both by Ecuadorian laws and by other countries. The concentrations of metals in rice plants did not correlate linearly with the total metal concentrations in the soil, nor with their bioavailability. However, the bioconcentration factors for As, Cd, Cu, Ni, and Zn could be predicted from bioavailability by a power law with exponents ranging from −0.724 to −1.625, which is typical of accumulator plants, where trace metal homeostasis plays an important role.

Antioxidant and Anti-Inflammatory Potential and Consumer Acceptance of Wafers Enriched with Freeze-Dried Raspberry Pomace

In this study, the effect of the addition of freeze-dried raspberry pomace on the content of phenolic compounds and the antioxidant and anti-inflammatory activity of wafers was investigated. Particular attention was paid to the biological activity of the potentially bioavailable fraction of polyphenols extracted via gastro-intestinal digestion. In the basic recipe for the waffle dough, flour was replaced with freeze-dried raspberry pomace in the amount of 10%, 20%, 30%, 50%, and 75%. The content of total phenolic compounds, phenolic acids, flavonoids, and anthocyanins in ethanol and buffer extracts and after in vitro digestion increased with the increase in the addition of pomace. A similar relationship was noted for antioxidant properties: ability to neutralize ABTS—2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and DPPH—1,1-diphenyl-2-picrylhydrazyl radicals, iron II chelating ability, and reduction power. The extracts obtained after the simulated digestion showed the highest activities, which confirms that the polyphenols are a potentially bioavailable fraction. Extracts from the fortified wafers effectively inhibited the activity of enzymes involved in the generation of free radicals and induction of inflammation, i.e., xanthine oxidase (XO), lipoxygenase (LOX), and cyclooxygenase 2 (COX-2). The lowest IC50 values were determined for extracts after in vitro digestion. The sensory evaluation of the prepared wafers showed that the wafers fortified with 20% pomace achieved optimal scores. Enrichment of confectionery products with waste products from the fruit and vegetable industry can be a good way to increase the proportion of biologically active polyphenols in the diet and brings benefits to the environment.

The Effect of Simulated In Vitro Digestion on Biological Activity of Viburnum opulus Fruit Juices

In the present study, an in vitro digestion method has been used to assay the influence of the physiological conditions in the mouth, stomach, and intestine on the stability and activity in different cell models of the main phenolic compounds from Viburnum opulus fresh juice (FJ), phenolic-rich juice (PJ), and the bioavailable fractions (DFJ and DPJ). The data obtained indicate that the V. opulus samples achieved after in vitro digestion had an influence on cellular glucose and lipid metabolism. The bioavailable fraction of both digested juices stimulated glucose uptake and decreased lipid accumulation by L6 myoblasts and HepG2 hepatocytes. Both DFJ and DPJ reduced the secretion of inflammatory cytokines by 3T3-L1 adipocytes: interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Simultaneously, DFJ and DPJ enhanced oxidative stress in MIN6 cells and decreased glucose-stimulated insulin secretion (GSIS). UPLC–MS analysis revealed qualitative and quantitative changes in hydroxycinnamic acids. In particular, the content of chlorogenic acid decreased drastically; its content in the bioavailable fraction was almost 7 times and 30 times lower than in the FJ and PJ, respectively. Our results suggested that although the phenolic compounds of V. opulus juices undergo transformation during digestion, they are still potent antioxidant agents with biological activity.

Cytoprotective Effects of Fish Protein Hydrolysates against H2O2-Induced Oxidative Stress and Mycotoxins in Caco-2/TC7 Cells

Many studies report the potent antioxidant capacity for fish protein hydrolysates, including radical scavenging activity and inhibition ability on lipid peroxidation (LPO). In this study, the in vitro cytotoxicity of protein hydrolysates from different salmon, mackerel, and herring side streams fractions was evaluated in the concentration range from 1 to 1:32 dilution, using cloned human colon adenocarcinoma cells TC7 (Caco-2/TC7) by MTT and PT assays. The protein hydrolysates’ antioxidant capacity and oxidative stress effects were evaluated by LPO and reactive oxygen species (ROS) generation, respectively. The antioxidant capacity for pure and bioavailable hydrolysate fraction was also evaluated and compared. Additionally, mycotoxin levels were determined in the fish protein hydrolysates, and their cytoprotective effect against T-2 toxin was evaluated. Both hydrolysates and their bioavailable fraction induced similar cell viability rates. The highest cytoprotective effect was obtained for the salmon viscera protein hydrolysate (HSV), which increased the cell viability by 51.2%. ROS accumulation induced by H2O2 and LPO was suppressed by all pure hydrolysates. The cytoprotective effect of hydrolysates was observed against T-2. Moreover, the different fish fraction protein hydrolysates contain variable nutrients and unique bioactive peptide composition showing variable bioactivity, which could be a useful tool in developing dietary supplements with different target functional properties.

Bioaugmentation and Bioaugmentation – Assisted Phytoremediation of Heavy Metals Contaminated Soil By a Synergistic Effect of Cyanobacteria Inoculation, Biochar, and Purtolaca Oleracea

In recent decades, soil contamination with heavy metals has become an environmental crisis due to their long-term stability and adverse biological effects. Therefore, bioremediation is an eco-friendly technology to remediate contaminated soil, that its efficiency requires further research. This study was conducted to comparatively investigate two strategies, including bioaugmentation by using Oscillatoria sp and bioaugmentation assisted phytoremediation by using Oscillatoria sp -portulaca oleracea for the bioremediation of heavy metal (Cr (III), Cr (VI), Fe, Al, and Zn) contaminated soil at 180 days. To facilitate the remediation process, various quantities of biochar (0, 0.5, 2, and 5% (w/w)) were used in the experiments. The results of the bioaugmentation showed a significant improvement in chlorophyll a, nitrogen, organic carbon contents of soil and decrease all heavy metal bioavailability and EC of soil. The remediation efficiency test using plants proved the success of remediation treatments. Moreover, the findings of bioaugmentation-assisted phytoremediation displayed an improvement in soil fertility and a substantial reduction in the bioavailable fraction of heavy metals, especially in soil amended with 5% biochar. Cyanobacteria inoculation and biochar amendment dramatically enhanced the root lengths and shoot heights of portulaca oleracea while it significantly decreased their heavy metal accumulation compared to the control. For all heavy metals, TF and BAC (except Zn) values ​​were found to be less than 1.0 at all treatments, illustrated the successful phytoextraction by the P. In conclusion, cyanobacteria inoculation along with biochar addition enhanced the TI quantities while diminished BAC and BCF values, suggesting the feasibility their applying in heavy metal contaminated soil for the facilitation of phytoremediation and their ability in pollutant immobilization.

Versatile artificial mer operons in Escherichia coli towards whole cell biosensing and adsorption of mercury

Mercury exists naturally and mainly as a man-made pollutant in the environment, where it exerts adverse effects on local ecosystems and living organisms. It is important to develop an appropriate synthetic biological device that recognizes, detects and removes the bioavailable fraction of environmental mercury. Both single-signal and double-signal output mercury biosensors were assembled using a natural mer operon as a template. Selectivity and sensitivity of whole-cell biosensors based on artificial mer operons were determined. Three whole-cell biosensors were highly stable at very high concentrations of mercuric chloride, and could detect bioavailable Hg(II) in the concentration range of 6.25–200 μM HgCl2. A novel Hg(II) bioadsorption coupled with biosensing artificial mer operon was assembled. This would allow Hg(II)-induced Hg(II) binding protein cell surface display and green fluorescence emission to be achieved simultaneously while retaining the linear relationship between fluorescent signal and Hg(II) exposure concentration. The present study provides an innovative way to simultaneously detect, quantify, and remove bioavailable heavy metal ions using an artificially reconstructed heavy metal resistance operon.