Poorly-crystalline components in aggregates from soils under different land use and parent material

Catena 144 (2016) 141–150

http://dx.doi.org/10.1016/j.catena.2016.05.012

Fe and Al compounds of low degree of crystallinity are important components for the development and conser- vation of soil structure in many soils. In this work, the influence of parent material and land use on the abundance of poorly-crystalline forms of Fe and Al was studied in six macroaggregate fractions from 28 soils. The soils select- ed are developed on two geological materials with very different composition: granites or amphibolites, and under two land uses: shrubland or agricultural. Poorly crystalline Fe and Al were extracted with oxalic acid–am- monium oxalate (inorganic and organic forms), and with pyrophosphate (organic forms). Soils developed on am- phibolite were richer in organic matter and poorly-crystalline Fe and Al compounds than soils developed on granite. Agricultural soils were impoverished in organic carbon and organic-complexed Al with respect to shrub- land soils, and enriched in inorganic poorly crystalline forms of Fe. The differences related to land use were more evident in the amphibolite soils. Aggregate stability, assessed by water-dispersible clay quantification, decreased in agricultural soils with respect to shrubland soils, in particular for those developed on amphibolite. This reduc- tion of aggregate stability in agricultural soils is likely due to a combination of several processes: loss of organic matter, higher pH, and an overall loss of poorly-crystalline Fe and Al compounds, in particular Al-organic matter complexes.

Applied Microbiology and Biotechnology, 2016, 100 (18), 7899–790

DOI: 10.1007/s00253-016-7558-9

Nisin production by Lactococcus lactis CECT 539 was followed in batch cultures in whey supplemented with different concentrations of glucose and in two realkalized fed-batch fermentations in unsupplemented whey, which were fed, respectively, with concentrated solutions of lactose and glucose. In the batch fermentations, supplementation of whey with glucose inhibited both the growth and bacteriocin production. However, fed-batch cultures were characterized with high productions of biomass (1.34 and 1.51 g l−1) and nisin (50.6 and 60.3 BU ml−1) in comparison to the batch fermentations in unsupplemented whey (0.48 g l−1 and 22.5 BU ml−1) and MRS broth (1.59 g l−1 and 50.0 BU ml−1). In the two realkalized fed-batch fermentations, the increase in bacteriocin production parallels both the biomass production and pH drop generated in each realkalization and feeding cycle, suggesting that nisin was synthesized as a pH-dependent primary metabolite. A shift from homolactic to heterolactic fermentation was observed at the 108 h of incubation, and other metabolites (acetic acid and butane-2,3-diol) in addition to lactic acid accumulated in the medium. On the other hand, the feeding with glucose improved the efficiencies in glucose, nitrogen, and phosphorus consumption as compared to the batch cultures. The realkalized fed-batch fermentations showed to be an effective strategy to enhance nisin production in whey by using an appropriate feeding strategy to avoid the substrate inhibition.

Pediocin SA-1: A selective bacteriocin for controlling Listeria monocytogenes in maize silages

Journal of Dairy Science, 99 (2016) 8070–8080

http://dx.doi.org/10.3168/jds.2016-11121

In this study, we assessed the potential as silage additive of a bacteriocin produced by Pediococcus acidilactici Northern Regional Research Laboratory (NRRL) B-5627 (pediocin SA-1). Maize was inoculated either with a bacterial starter alone (I) or in combination with the bacteriocin (IP), and untreated silage served as control. We monitored the products of fermentation (ethanol, and lactic and acetic acids), the microbial population, and the presence of the indicator strain Listeria monocytogenes Colección Española de Cultivos Tipo (CECT) 4032 (1 × 105 cfu/g) after 1, 2, 5, 8, 16, and 30 d of ensiling. Our results indicated antilisterial activity of the bacteriocin, anticipating the disappearance of L. monocytogenes in IP compared with I and control silages. The PCR-denaturing gradient gel electrophoresis analysis revealed the addition of the bacteriocin did not affect the bacterial communities of the spontaneous fermentation, and the inoculant-containing bacteria (Lactobacillus plantarum, Lactobacillus buchneri, and Enterococcus faecium) were found in addition to the bacterial communities of untreated maize silages in I and IP silages. Both treatments increased the concentration of antimicrobial compounds (acetic acid, ethanol, and 1,2-propanodiol) and led to lower residual sugar contents compared with the control, which would provide enhanced aerobic stability. The fact that the identified species L. plantarum, L. buchneri, and E. faecium produce some of these inhibitory compounds, together with their persistence throughout the 30 d of fermentation, suggest these bacteria could actively participate in the ensiling process. According to these results, pediocin SA-1 could be used as an additive to control the presence of L. monocytogenes in maize silages selectively, while improving their fermentative quality and eventually their aerobic stability.

Video Presentación del CIA

Simultaneous production of amylases and proteases by Bacillus subtilis in brewery wastes

Brazilian Journal of Microbiology, 47, 2016, 665–674

http://dx.doi.org/10.1016/j.bjm.2016.04.019

The simultaneous production of amylase (AA) and protease (PA) activity by Bacillus subtilis UO-01 in brewery wastes was studied by combining the response surface methodology with the kinetic study of the process. The optimum conditions (T = 36.0 °C and pH = 6.8) for high biomass production (0.92 g/L) were similar to the conditions (T = 36.8 °C and pH = 6.6) for high AA synthesis (9.26 EU/mL). However, the maximum PA level (9.77 EU/mL) was obtained at pH 7.1 and 37.8 °C. Under these conditions, a considerably high reduction (between 69.9 and 77.8%) of the initial chemical oxygen demand of the waste was achieved. In verification experiments under the optimized conditions for production of each enzyme, the AA and PA obtained after 15 h of incubation were, respectively, 9.35 and 9.87 EU/mL. By using the Luedeking and Piret model, both enzymes were classified as growth-associated metabolites. Protease production delay seemed to be related to the consumption of non-protein and protein nitrogen. These results indicate that the brewery waste could be successfully used for a high scale production of amylases and proteases at a low cost.

Antioxidant ability of potato (Solanum tuberosum) peel extracts to inhibit soybean oil oxidation

Eur. J. Lipid Sci. Technol. (2016)

doi:10.1002/ejlt.201500419

Potato peels are an agro industrial waste of one of the major crops worldwide. However, the potential of potato peels as source of antioxidants in the food industry is not yet sufficiently known. In this work, the antioxidant effect of potato peel extract (PPE) on oxidative stability of soybean oil was evaluated. We found that the addition of low PPE concentrations to soybean oil at four different levels, expressed as chlorogenic acid concentrations (14.01, 20.37, and 31.94 ppm), affected lipid oxidation indices (peroxide, anisidine, and conjugated dienes values), fatty acid composition, and volatile compounds. Antioxidant effect increased with increasing dose extract. Inhibition percentages of hexanal production increased with the PPE concentration. In addition, low concentrations of PPE showed higher oxidation stability than control untreated samples. Overall, our study shows that low concentrations of PPE exhibited promising antioxidant activity to be applied over a wider range of products in the food industry.

Practical applications: The prevention of lipid oxidation during processing and storage of food products is of great concern in order to obtain products of high quality and health. Together with the fact that synthetic antioxidants may constitute a potential health hazard for consumers, interest in natural antioxidants and search on naturally occurring compounds with antioxidant activity has increased dramatically. The study of the antioxidant capacity of potato peel extracts to inhibit soybean oil oxidation provides information about an alternative antioxidant further are by-products of agro-industries and their use could represent a significant step toward maintaining an environmental balance.

Soil organic matter stabilization at the pluri-decadal scale: Insight from bare fallow soils with contrasting physicochemical properties and macrostructures

Geoderma 275 (2016) 48–54

http://dx.doi.org/10.1016/j.geoderma.2016.04.009

Physical protection is recognized as one of the main processes governing soil organic matter stabilization, but its importance over long time scales (decades to century) is being discussed. In this work, we used data from a long-term bare fallow experiment initiated in 1928 in Versailles (France) to investigate such process: given that no organic carbon inputs occurred since 1928, all the organic matter present had pluri-decadal to centennial mean residence times. The annual addition of mineral amendments (CaCO3 or KCl) produced contrasting superficial soil structures in some plots compared to non-amended plots. We hypothesized that a more aggregated and stable soil structure would likely be associated with higher organic carbon stocks. Stability of soil structure was quantified using three complementary tests: slow wetting to study macroaggregation, moderate dispersion compared to strong dispersion to study microaggregation. The CaCO3 plots had the highest macroaggregate stability, and KCl plots the lowest but microaggregation at the silt-size scale was similar for the three soils. After 79 years of bare fallow soil organic carbon stocks in the bulk soil were about 25% higher in the CaCO3 plots than in the KCl and reference plots. This relative increment was due to a higher amount of silt and clay-associated soil organic matter in CaCO3 plots, as a consequence of better physical or physicochemical protection at these scales, with a less important role of physical protection within stable macroaggregates.

Soil organic matter stabilization at the pluri-decadal scale: Insight from bare fallow soils with contrasting physicochemical properties and macrostructures

Geoderma 275 (2016) 48–54

http://dx.doi.org/10.1016/j.geoderma.2016.04.009

Physical protection is recognized as one of the main processes governing soil organic matter stabilization, but its importance over long time scales (decades to century) is being discussed. In this work, we used data from a long-term bare fallow experiment initiated in 1928 in Versailles (France) to investigate such process: given that no organic carbon inputs occurred since 1928, all the organic matter present had pluri-decadal to centennial mean residence times. The annual addition of mineral amendments (CaCO3 or KCl) produced contrasting superficial soil structures in some plots compared to non-amended plots. We hypothesized that a more aggregated and stable soil structure would likely be associated with higher organic carbon stocks. Stability of soil structure was quantified using three complementary tests: slow wetting to study macroaggregation, moderate dispersion compared to strong dispersion to study microaggregation. The CaCO3 plots had the highest macroaggregate stability, and KCl plots the lowest but microaggregation at the silt-size scale was similar for the three soils. After 79 years of bare fallow soil organic carbon stocks in the bulk soil were about 25% higher in the CaCO3 plots than in the KCl and reference plots. This relative increment was due to a higher amount of silt and clay-associated soil organic matter in CaCO3 plots, as a consequence of better physical or physicochemical protection at these scales, with a less important role of physical protection within stable macroaggregates.

Monitoring benthic microflora in river bed sediments: a case study in the Anllóns River (Spain)

Journal of Soils and Sediments (2016) 16, 1825–1839

DOI: 10.1007/s11368-016-1395-4

The objectives of this study were to investigate the abundance and composition of the superficial biofilm on the bed sediments of the Anllóns River (NW Spain), to evaluate the relationships between biochemical parameters and biological methods based on identification and counting, and to explore the relationships between biofilm growth and the properties of the sedimentary habitat, mainly the trophic state.

Bed sediment samples (0–5 cm) were collected in two different seasons (winter and summer) at four sampling sites along the river course. Physicochemical properties of pore waters and sediments were determined. Biological properties included the determination of dehydrogenase activity (DHA) and phytopigment (Chl a Chl b and total carotenoids) concentrations, as well as taxonomic identification. For taxonomic identification, two sampling methods were compared: the Pasteur pipette method and a mini-corer method. Total and relative algal abundances (TA and RA, respectively) and genus richness were calculated. The relationships between the different variables were examined using Pearson correlations and principal component analysis.

The main taxa belonged to Chlorophyta, Cyanophyta, Euglenophyta, and Heterokontophyta. The most abundant class was Bacillariophyceae, which represents >86 % of the total abundances in the superficial sediments. The highest total algal abundance and genus richness were observed in summer at the river mouth, where DHA and phytopigment concentrations were also the highest. The statistical analysis revealed positive correlations between TA and the biochemical parameters (DHA and phytopigments) as well as positive relationships of these three parameters with the physicochemical properties of the sediments, such as electrical conductivity, and the concentrations of fine particles, C, N, S, and total P.

The results of this study reveal the positive relationships between the biochemical properties (phytopigments and respiratory activity) and total algal abundances determined by taxonomic identification and counting. All of these properties presented evidence of a clear influence of the nutrients and organic matter contents of the sediments, pointing to the importance of the site conditions, particularly the trophic state, in the development of benthic microflora.

A biorefinery scheme for residual biomass using autohydrolysis and organosolv stages for oligomers and bioethanol production

Energy & Fuels

DOI: 10.1021/acs.energyfuels.6b00277

Straw is one of the main lignocellulosic waste produced during cereal crop cultivation. The abundance of barley straw makes it a good candidate for bioethanol production. This work deals with barley straw pretreatment by means of autohydrolysis in order to get xylooligosaccharides in the liquid phase, followed by an organosolv treatment using ethanol to increase the solid phase enzymatic susceptibility. Up to 17.4 g oligomers/L were obtained in the hydrothermal stage, in which practically all the cellulose and lignin remained in the solid phase. The solid phase from the hydrothermal-delignification was subjected to an experimental design in order to study the effect of pretreatment conditions in the bioethanol production, with values of solids concentrations in the range 7.7 to 20 weight % and values of enzyme loading in the range 14 FPU/g to 6 FPU/g. In the experiments carried out at a liquid to solid ratio = 4 g/g it is possible to obtain 31.6 g ethanol/L in just 9 h (corresponding to 100% ethanol conversion), with optimum results of 44.5 g ethanol/L in 46 h (90-93% glucose to ethanol conversion) and with a maximum concentration of 48.7 g ethanol/L in 89 h (79% conversion). The combination of a hydrothermal pretreatment (under conditions that lead to the recovery of high amounts of hemicellulosic by-products), followed by an organosolv treatment under mild conditions turns out to be suitable for second generation bioethanol production, applying a high solids loading, by means of fed-batch simultaneous saccharification and fermentation.

Characterization of virgin olive oils produced with autochthonous Galician varieties

Food Chemistry 212 ( 2016) 162–171

http://dx.doi.org/10.1016/j.foodchem.2016.05.135

The interest of Galician oil producers (NW Spain) in recovering the ancient autochthonous olive varieties Brava and Mansa has increased substantially in recent years. Virgin olive oils produced by co-crushing both varieties in two different proportions, reflecting the usual and most common practice adopted in this region, have gradually emerged for the production of virgin olive oils. Herein, the sensory and chemical characteristics of such oils were characterized by quality and genuineness-related parameters. The results of chemical analysis are discussed in terms of their effective contribution to the sensory profile, which suggests useful recommendations for olive oil producers to improve the quality of oils. Antioxidant compounds, together with aromas and coloured pigments were determined, and their contribution in determining the functional value and the sensory properties of oils was investigated. In general, given the high levels of phenolic compounds (ranging between 254 and 375 mg/kg oil), tocopherols (about 165 mg/kg oil) and carotenoids (10–12 mg/kg oil); these are oils with long stability, especially under dark storage conditions, because stability is reinforced with the contribution of chlorophylls (15–22 mg/kg oil). A major content of phenolic compounds, as well as a predominance of trans-2-hexen-1-al within odor-active compounds (from 897 to 1645 μg/kg oil), responsible for bitter sensory notes. This characterization allows to developing new antioxidant-rich and flavour-rich VOOs, when co-crushing with a higher proportion of Brava olives, satisfying the consumers’ demand in having access to more healthy dishes and peculiar sensory attributes.

Foto de Grupo - Septiembre de 2016

Investigadores del CIA en Vigo

Promoting sustainability in the mussel industry: mussel shell recycling to fight fluoride pollution

Journal of Cleaner Production, 131 (2016) 485–490

http://dx.doi.org/10.1016/j.jclepro.2016.04.154

Taking into account a background situation where some industrial activities greatly influence fluoride pollution, while other industries generate by-products that could be effective as fluoride bio-sorbents, and bearing in mind sustainability and environmental concern, batch-type experiments were performed to study fluoride sorption/desorption on individual (un-amended) and mussel shell-amended soils and materials. Specifically, the research focused on a forest soil, a vineyard soil, pyritic material, granitic material, and ground mussel shell, as well as on both soils and the pyritic and granitic materials amended with mussel shell. The main findings of the research indicate that the shell amendment clearly increased fluoride sorption in the pyritic material (reaching more than 90%), showing no effect as regards fluoride desorption from this material. The amendment caused a slight increase in fluoride sorption on forest soil, as well as a slight decrease in fluoride desorption from it. The un-amended vineyard soil and the un-amended granitic material had lower fluoride-retention capacity than the forest soil and pyritic material, and it did not change after amending with mussel shell. The mussel shell by itself showed the lowest fluoride-retention potential among the tested materials. As a conclusion, and focusing on applicability, these results can be useful to program the correct use of mussel shell amendment on soils and even on degraded environments with the aim of increasing fluoride retention or removal, thus decreasing risk of environmental pollution due to excessive fluoride concentrations in solid and/or liquid media, also facilitating recycling, sustainability and cleaner production in the mussel shell industry.

State of the art on public risk assessment of combined human exposure to multiple chemical contaminants

Trends in Food Science & Technology, 55 (2016) 11–28

http://dx.doi.org/10.1016/j.tifs.2016.06.011

Concern about the effects on health of exposure of combined chemicals present in food, air or water are increasing nowadays. However, mechanism and effects of combined chemical contaminants are still poorly know.

This review deals with the variety of routes of these chemicals when enter the human body. The gaol is the development of a mechanism-based and quantitative framework for risk assessment to estimate the impact on human health and prevent exposure to multiple chemicals.

It has been shown that new studies should be developed taking into account cumulative effect of these substances and different tiers as external exposition, dietary exposition, lifestyle, age and economic factors. New techniques must also be implemented, mainly “omic” techniques, bioassay systems, mathematical modelling, quantitative structure-activity relationship models, and threshold of toxicological concern to develop databases. In conclusion, several programs should continuously be developed by different health agencies to have a better understanding of the effect of these substances and to develop a unified policy.

Kinetic modelling of mancozeb hydrolysis and photolysis to ethylenethiourea and other by-products in water

Water Research 102 (2016) 561–571

http://dx.doi.org/10.1016/j.watres.2016.07.006

The aim of this study was to propose kinetic models suitable for reproducing and predicting mancozeb (Mz) conversion to by-products as a function of the operational conditions. The main factors (pH, temperature and light) potentially affecting the mancozeb degradation in aqueous models were studied by a multifactorial screening design. In addition, the response surface methodology (RSM) was applied to evaluate the interactive effects of these factors on ethylenethiourea (ETU) formation. The response surface revealed that the best degradation conditions to minimize mancozeb conversion to ETU were low pH (2), low temperature (25 °C) and darkness. Under these conditions, the percentage of mancozeb remained in the solution at 72 h was approximately 10% of the initial concentration and the percentage of ETU conversion was 5.4%. However, according to the model, in surface waters under typical environmental conditions (pH 8, 25 °C and light) the percentage of mancozeb conversion to ETU would be about 17.5%. The proposed model provides a satisfactory interpretation of the experimental data obtained during the hydrolysis of mancozeb.

Valorization of biosorbent obtained from a forestry waste: Competitive adsorption, desorption and transport of Cd, Cu, Ni, Pb and Zn

Ecotoxicology and Environmental Safety, 131(2016) 118–126

http://dx.doi.org/10.1016/j.ecoenv.2016.05.007

Bark from Pinus pinaster is one of the most abundant forestry wastes in Europe, and among the proposed technologies for its reutilization, the removal of heavy metals from wastewater has been gaining increasing attention. In this work, we have studied the performance of pine bark for heavy metal biosorption on competitive systems. Pb, Cu, Ni, Zn and Cd sorption and desorption at equilibrium were studied in batch experiments, whereas transport was studied in column experiments. Batch experiments were performed adding simultaneously different concentrations (0.08–3.15 mM) of two or more metals in solution to pine bark samples. Column experiments were performed with 10 mM solutions of two metals or a 5 mM solution of the five metals. In general, the results under competitive conditions were different to those obtained in monoelemental experiments. The multi-metal batch experiments showed the adsorption sequence Pb≈Cu>Cd>Zn>Ni for lower metal doses, Pb>Cu>Cd>Zn>Ni for intermediate doses, and Pb>Cu>Cd≈Zn≈Ni for high metal doses. Desorption followed the sequence Pb<Cd<Cu<Zn<Ni for the lowest metal doses, and Pb<Cu<Zn<Cd<Ni for the highest ones. The bi-metal batch experiments indicated that Cu and Pb suffered the highest retention, with high capacity to displace Cd, Ni and Zn from adsorption sites on pine bark. The transport experiments produced comparable results to those obtained in the batch experiments, with pine bark retention capacity following the sequence Pb>Cu>Zn>Cd>Ni. The presence of a second metal affected the transport of all the elements studied except Pb, and confirmed the strong influence of Pb and Cu on the retention of the other metals. These results can help to appropriately design decontamination systems using this forestry waste.

Phosphorus retention on forest and vineyard soil samples, mussel shell, pine-sawdust, and on pyritic, granitic and waste materials

Geoderma, 280 (2016) 8–13

http://dx.doi.org/10.1016/j.geoderma.2016.06.003

Focusing on P, we used batch-type experiments to study P retention on various materials: a forest soil sample, a vineyard soil sample, finely and coarsely ground mussel shell, pine-sawdust, pyritic material, granitic material, mussel shell calcination ash, slate processing fines, and three different mixtures that included three components: sewage sludge, mussel shell ash, and calcined mussel shell or pine wood ash. The pyritic material and the mussel shell ash showed the highest P retention capacity, reaching > 95%. The lowest P retention (< 60%) corresponded to the pine-sawdust and slate processing fines. Data fitted satisfactorily to the Freundlich model, unless in the case of pine-sawdust and slate fines; however, only forest and vineyard soil samples can be satisfactorily adjusted to the Langmuir model. These results could be useful to program appropriate management practices, especially when focusing on controlling P concentrations in different environmental compartments, as well as to correctly recycle the by-products and waste materials assayed.

Competitive and non-competitive cadmium, copper and lead sorption/desorption on wheat straw affecting sustainability in vineyards

Journal of Cleaner Production

http://dx.doi.org/10.1016/j.jclepro.2016.09.021

The novelty of this work lies on the consideration of wheat straw to retain Cu and other heavy metals in vineyards, in addition to its known potential to decrease erosion, thus facilitating the growth of new vine plants and contributing to sustainability in vineyard production. In this study we used batch-type experiments to investigate Cd, Cu and Pb competitive and non-competitive sorption/desorption on wheat straw. In non-competitive experiments, sorption sequence was Pb > Cd > Cu when the lowest molar concentrations (0.5 mmol L−1) were added, and Pb > Cu > Cd when the highest molar concentrations (6.0 mmol L−1) were added. Sorption curves indicated clearly higher sorption for Pb, lower initial sorption in the case of Cu, and certain trend to saturation of sorption sites for Cd. Data showed good adjustment to the Langmuir model just for Cd, whereas the Freundlich equation fitted well for all three metals. Desorption rates were low, in the order Pb < Cd < Cu. In the competitive experiment, the sorption sequence was Pb > Cu > Cd. The results indicate that competition clearly affected to Cd sorption, especially when the highest concentrations (6 mmol L−1) of the three heavy metals were added. The highest percentage of desorption in the competitive system corresponded to Cd, whereas Pb and Cu experienced clearly lower release. Comparing competitive and non-competitive experiments, Pb sorption was equivalent in the non-competitive and competitive trials, Cu sorption was slightly higher in the non-competitive than in the competitive experiment, and Cd sorption was clearly higher in the non-competitive trial. Percentage desorption decreased for Pb and for Cu in the competitive trial, whereas it was clearly higher for Cd in the competitive than in the non-competitive experiment. The overall results indicate that Pb, Cu and Cd can be retained by wheat straw (especially Cu and Pb), thus decreasing risks of pollution, which could be used to treat polluted waters, and could also give additional value to wheat straw mulching used to protect vineyards from erosion and Cu (and other heavy metals) pollution, thus contributing to sustainability in this productive sector.

Biological activities and novel applications of chalcones

Planta Daninha

http://dx.doi.org/10.1590/S0100-83582016340300022

This review provides information on the biological activities of chalcones (whether natural or synthetic derivatives) on different organisms, as well as an overview of the functions and possible new applications of these plant secondary metabolites on crop protection, as eco-friendly pesticides and weed control agents. Naturally occurring chalcones have been used in traditional medicine for many years; however, recent scientific advances have shown that these molecules have a broad range of biological activities in a variety of organisms. A review on the major sources of chalcones and the main molecular events involved in the modes of action of these natural products is achieved. Chalcones are molecules with a broad spectrum of biological activities, which are of great interest in agriculture to control weeds and unwanted pests.

Foto de Grupo - Septiembre de 2016

Investigadores del CIA en Ourense

Feruloyl esterase production by Aspergillus terreus CECT 2808 and subsequent application to enzymatic hydrolysis

Enzyme and Microbial Technology, 91 (2016) 52–58

http://dx.doi.org/10.1016/j.enzmictec.2016.05.011

Ferulic acid esterases (FAE) were produced by Aspergillus terreus CECT 2808 from vine trimming shoots (VTS) and corn cob. Later, the fungal extracts thus obtained were used to enzymatically release ferulic acid (FA) from both substrates. Our findings showed a higher FAE activity in the enzymatic extracts produced on corn cob (0.070 ± 0.004 U/mL). Nevertheless, the enzymatic extracts produced on VTS demonstrated a better performance for FA release from both corn cob (2.05 ± 0.01 mg/g) and VTS (0.19 ± 0.003 mg/g). This result was probably because of the higher xylanase/FAE ratio determined in VTS extract. Therefore, an additional assay was carried out by supplementing corn cob extract with a commercial xylanase to test the influence of FAE/xylanase ratio in FA release. The results revealed the relevance of the FAE/xylanase ratio for an optimal FA release.

Carbon fractionation in a mine soil amended with compost and biochar and vegetated with Brassica juncea L

Journal of Geochemical Exploration

Volume 169, October 2016, Pages 137–143

http://dx.doi.org/10.1016/j.gexplo.2016.07.021

The aim of this study was to evaluate the effect of the application of compost and biochar as soil amendments and planting of Brassica juncea L. to improve soil carbon fractions in a copper mine soil. A greenhouse experiment was carried out for 3 months amending the mine soil with increasing proportions of compost and biochar mixture (20, 40, 80 and 100%) and planting Brassica juncea L. The results showed that the addition of amendments increased soil pH from 2.7 to 8.66, TC from undetectable levels to 149 g kg− 1, SOC from undetectable levels to 128 g kg− 1 and TN from undetectable levels to 11.13 g kg− 1. Organic amending also increased DOC (dissolved organic carbon) from undetectable levels to 25.56 g kg− 1, FOM (carbon in the free organic matter) from undetectable levels to 38.04 g kg− 1, FAP (carbon in fulvic acids removed with phosphoric acid) from undetectable levels to 15.57 g kg− 1, as well as increased the humification ratio, the humification index, the polymerisation rate and the organic carbon in the humified fractions (humic acids, fulvic acids and humin). Soils amended and vegetated with Brassica juncea showed lower values for FOM and FAP and higher values for humification ratio and polymerisation rate than the amended not-vegetated soils. Therefore, the combination of compost and biochar as soil amendment can be considered an efficient treatment to improve soil carbon fractions, making it suitable for a field scale application.