Microbial community structure in forest soils treated with a fire retardant

The influence of a fire retardant (Firesorb, an acrylic–acrylamide copolymer) on the microbial community structure determined by phospholipid fatty acid (PLFA) analysis was examined under laboratory conditions using two different textured soils under pine forest. Firesorb was added to unheated and heated soil samples (350°C for 10 min followed by reinoculation, to mimic a forest fire) at three levels of application (none, usual and three times the usual levels), and measurements were made after 12 weeks of incubation. The relative importance of the three factors considered on the PLFA profiles was as follows: soil heating ≫ soil texture ≈ Firesorb treatment. In the unheated soils, Firesorb had a larger effect than soil texture, while the opposite was found in the heated soils. Soil heating reduced the total PLFAs, while Firesorb tended to increase them in both the unheated and heated soils. Soil heating decreased the PLFAs indicative of gram-positive (G⁺) bacteria and tended to increase the fatty acids associated with gram-negative (G⁻) bacteria and, to a lesser extent, the PLFA 18:2ω6, considered to be predominantly of fungal origin. Firesorb treatment decreased the G⁻/G⁺ bacteria ratio in the heated soils but tended to increase it in the unheated soils, the effect being dose dependent.     

Polymorphism and Genetic Diversity for the Seed Storage Proteins in Spanish Cultivated Einkorn Wheat (Triticum monococcum L. ssp. monococcum)

The seed storage protein composition of one collection of cultivated einkorn wheat (Triticum monococcum L. ssp. monococcum) of Spanish origin has been analysed by SDS-PAGE and A-PAGE. Three allelic variants were detected for the Glu-A1^m, whereas up to six alleles were detected for the Glu-A3^m. For the gliadins, 7 and 14 alleles for the Gli-A1^m and Gli-A2^m were found between the evaluated accessions. Internal variability was detected in some of these materials, which could be related to the landrace nature of them. Up to 48 different genotypes based on the origin and seed storage protein composition have been identified. Further researches on these materials must be carried out for determining the variability degree in morphological traits that could complement the evaluation for their safeguard.     

Application of isotope dilution analysis for the evaluation of extraction conditions in the determination of total selenium and selenomethionine in yeast-based nutritional supplements

Isotope dilution analysis (IDA) has been used to quantify total selenium, total solubilized selenium, and the selenomethionine (SeMet) amount in yeast and yeast-based nutritional supplements after acid microwave digestion and different enzymatic extraction procedures. For this purpose, both a (77)Se-enriched SeMet spike, previously synthesized and characterized in our laboratory, and a (77)Se(VI) spike were used. In the analysis of the nutritional supplements, the SeMet spike was added to the sample and extracted under different conditions, and the (78)Se/(77)Se and (80)Se/(77)Se isotope ratios were measured as peak area ratios after high-performance liquid chromatography (HPLC) separation and inductively coupled plasma mass spectrometry (ICP-MS) detection. The formation of SeH(+) and mass discrimination were corrected using a natural SeMet standard injected every three samples. Similarly, total solubilized selenium was measured in the extracts after enzymatic hydrolysis using the (77)Se-enriched SeMet as a spike by direct nebulization without a chromatographic separation. To establish a mass balance, total selenium was also determined by IDA-ICP-MS on the yeast tablets after microwave digestion using (77)Se(VI) as a spike. Results showed that all enzymatic procedures tested were able to solubilize total selenium quantitatively from the solid. However, the recovery for the species SeMet, the major selenium compound detected, was seriously affected by the enzymatic procedure employed and also by the matrix composition of the supplement evaluated. For the yeast sample, SeMet recovery increased from 68 to 76% by the combined use of driselase and protease. For the nutritional supplements, the two most effective procedures appeared to be protease and driselase/protease, with a SeMet recovery ranging from 49 to 63%, depending upon the supplement evaluated. In the case of in vitro gastrointestinal enzymolysis, the results obtained showed 26-37% SeMet recovery, while the rest of selenium was solubilized as other unknown compounds (probably Se-containing peptides).     

Heterogeneous aspects of lipid oxidation in dried microencapsulated oils

This work was aimed at studying lipid oxidation in dried microencapsulated oils (DMOs) during long-term storage. Samples were prepared by freeze-drying of emulsions containing sodium caseinate and lactose as encapsulating components. Evaluation of lipid oxidation was approached by quantitative analysis of nonvolatile lipid oxidation products and tocopherol. Lipid oxidation products were analyzed by separation of polar compounds by adsorption chromatography followed by HPSEC with refraction index detection for quantitation of oxidized triglyceride monomers, dimers, and oligomers. The analytical method applied enabled the detection of different oxidative patterns between the free and encapsulated oil fractions. The free oil fraction of DMOs showed a typical oxidative pattern for oils in continuous phase, which consisted of a clear induction period, in which hydroperoxides (oxidized triglyceride monomers) accumulated, before oxidation accelerated. The end of the induction period was marked by the total loss of tocopherol and the initiation of polymerization. On the contrary, the encapsulated oil showed a pattern characteristic of a mixture of oils with different oxidation status. Thus, high contents of advanced oxidation compounds (polymerization compounds) were detected when the antioxidant (tocopherol) was still present in high amounts. It is concluded that the encapsulated oil was comprised of oil globules with very different oxidation status. The results obtained in this study gave evidence of heterogeneous aspects of lipid oxidation in a dispersed-lipid food system.     

Chemopreventive activity of polyphenolics from black Jamapa bean (Phaseolus vulgaris L.) on HeLa and HaCaT cells

The antiproliferative effects of 100% methanol crude extract and of Toyopearl and silica gel fractions from the seed coats of black Jamapa beans (Phaseolus vulgaris L.) were evaluated using HeLa, human adenocarcinoma cells, and HaCaT, human premalignant keratinocytes. The 100% methanol crude extract [172.2 microM equiv of (+)-catechin] increased adhesion of HeLa cells; however, 3- and 5-fold higher concentrations decreased the number of cells attached as a function of the treatment time. The highest concentration tested diminished the cell adhesion until 40% (after 24 h) to almost 80% (after 72 h). The IC50 values showed that the 100% methanol crude extract was the most effective inhibitor of HeLa cell proliferation, even when it was dissolved in dimethylsulfoxide (DMSO) [34.5 microM equiv of (+)-catechin] or in medium [97.7 microM equiv of (+)-catechin]. The Toyopearl 5 (TP5) fraction and silica gel 2 (SG2) fraction inhibited 60% of the HeLa cell proliferation. The IC50 was 154 microM equiv of (+)-catechin of the 100% methanol crude extract on HaCaT cells. Toyopearl fractions TP4 and TP6 significantly inhibited HaCaT cell proliferation, but the silica gel fractions did not have a significant effect. The 100% methanol crude extract (35 microg of dry material/mL) decreased the number of HeLa cells in the G0/G1 phase from 68.9% (for control cells) to 51.4% (for treated cells) and increased apoptosis (2.9 and 21.2% for control and treated cells, respectively). The results indicated that black Jamapa beans could be a source of polyphenolic compounds, which have an inhibitory effect toward HeLa cancer cells but are less aggressive on HaCaT premalignant cells.     

Use of Aloe vera gel coating preserves the functional properties of table grapes

Table grapes (Vitis vinifera L. cv. Crimson Seedless) were coated with Aloe vera gel according to our developed patent (SP Patent P200302937) and then stored for 35 days at 1 degrees C, and the subsequent shelf life (SL) was monitored at 20 degrees C. Uncoated clusters showed a rapid loss of functional compounds, such as total phenolics and ascorbic acid. These changes were accompanied by reduction of the total antioxidant activity (TAA) and increases in total anthocyanins, showing an accelerated ripening process. On the contrary, table grapes coated with Aloe vera gel significantly delayed the above changes, such as the retention of ascorbic acid during cold storage or SL. Consequently, Aloe vera gel coating, a simple and noncontaminating treatment, maintained the functional properties during postharvest storage of table grapes.     

Simultaneous determination of eight water-soluble vitamins in supplemented foods by liquid chromatography

A fast, simple, and reliable method for the isolation and determination of the vitamins thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, folic acid, cyanocobalamin, and ascorbic acid in food samples is proposed. The most relevant advantages of the proposed method are the simultaneous determination of the eight more common vitamins in enriched food products and a reduction of the time required for quantitative extraction, because the method consists merely of the addition of a precipitation solution and centrifugation of the sample. Furthermore, this method saves a substantial amount of reagents as compared with official methods, and minimal sample manipulation is achieved due to the few steps required. The chromatographic separation is carried out on a reverse phase C18 column, and the vitamins are detected at different wavelengths by either fluorescence or UV-visible detection. The proposed method was applied to the determination of water-soluble vitamins in supplemented milk, infant nutrition products, and milk powder certified reference material (CRM 421, BCR) with recoveries ranging from 90 to 100%.     

Application of a plant bioassay for the evaluation of ecotoxicological risks of heavy metals in sediments affected by mining activities

Purpose

The objective of this work was to evaluate the effectiveness of a plant bioassay (Phytotoxkit®) for screening ecotoxicological risks in sediments affected by mining activities.

Materials and methods

A total of 42 sediment samples affected by mining activities were studied, including 39 sediment samples from the Sierra Minera, Spain, an area affected by old extraction procedures, and three sediments from an area affected by opencast mining. These three samples were then mixed with limestone filler at 10, 20 and 30 %, providing nine stabilised samples. The total and soluble metal(loid) content (As, Cd, Cu, Fe, Pb and Zn) was determined in all samples, and the Phytotoxkit® bioassay was applied to determine the ecotoxicological effect of this procedure.

Results and discussion

The stabilised material had a neutral pH and low soluble metal(loid) concentration, similar to that of samples in which a natural attenuation process had taken place because of mixing with surrounding carbonate-rich materials. An ecotoxicological survey identified the low toxicity levels of the stabilised samples.

Conclusions

The applied bioassay is a good tool for screening metal(loid) contamination in areas affected by mining activities, since it provides information on both natural and simulated attenuation processes. The mixing of sediments with limestone filler could be applied to the remediation of zones affected by mining activities, because the toxicological effect on the tested organisms in the stabilised sediments was reduced significantly and the metal(loid) content was diminished.     

Chromoplast morphology and beta-carotene accumulation during postharvest ripening of Mango Cv. 'Tommy Atkins'

Accumulation of beta-carotene and trans-cis isomerization of ripening mango mesocarp were investigated as to concomitant ultrastructural changes. Proceeding postharvest ripening was shown by relevant starch degradation, tissue softening, and a rising sugar/acid ratio, resulting in a linear decrease (R (2) = 0.89) of a ripening index (RPI(KS)) with increasing ripening time. A modest accumulation of all-trans-beta-carotene and its cis isomers resulted in a slight pigmentation of the mango chromoplasts, because ambient temperatures of 18.2-19.5 degrees C provided suboptimal ripening conditions, affecting color development and beta-carotene biosynthesis. The ultrastructures of chromoplasts from mango mesocarp and carrot roots were comparatively studied by means of light and transmission electron microscopy. Irrespective of the ripening stage, mango chromoplasts showed numerous plastoglobuli varying in size and electron density. They comprised the main part of carotenoids, thus supporting the partial solubilization of the pigments in lipid droplets. However, because different pigment-carrying tubular membrane structures were also observed, mango chromoplasts were assigned to the globular and reticulotubular types, whereas the crystalline type was confirmed for carrot chromoplasts. The large portions of naturally occurring cis-beta-carotene in mango fruits contrasted with the predominance of the all-trans isomer characteristic of carrots, indicating that the nature of the structure where carotenoids are deposited and the physical state of the pigments are crucial for the stability of the all-trans configuration.     

Antibacterial activity of coffee extracts and selected coffee chemical compounds against enterobacteria

The in vitro antimicrobial activity of commercial coffee extracts and chemical compounds was investigated on nine strains of enterobacteria. The antimicrobial activity investigated by the disc diffusion method was observed in both the extracts and tested chemical compounds. Even though pH, color, and the contents of trigonelline, caffeine, and chlorogenic acids differed significantly among the coffee extracts, no significant differences were observed in their antimicrobial activity. Caffeic acid and trigonelline showed similar inhibitory effect against the growth of the microorganisms. Caffeine, chlorogenic acid, and protocatechuic acid showed particularly strong effect against Serratia marcescens and Enterobacter cloacae. The IC(50) and IC(90) for the compounds determined by the microtiter plate method indicated that trigonelline, caffeine, and protocatechuic acids are potential natural antimicrobial agents against Salmonella enterica. The concentrations of caffeine found in coffee extracts are enough to warrant 50% of the antimicrobial effect against S. enterica, which is relevant to human safety.