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981.
Padilla MN Martínez-Rivas JM Pérez AG Sanz C 《Journal of agricultural and food chemistry》2012,60(26):6477-6482
The aim of this work was to characterize the thermal inactivation parameters of recombinant proteins related to the biosynthesis of virgin olive oil (VOO) volatile compounds through the lipoxygenase (LOX) pathway. Three purified LOX isoforms (Oep2LOX1, Oep1LOX2, and Oep2LOX2) and a hydroperoxide lyase (HPL) protein (OepHPL) were studied. According to their thermal inactivation parameters, recombinant Oep1LOX2 and Oep2LOX2 could be identified as the two LOX isoforms active in olive fruit crude preparations responsible for the synthesis of 13-hydroperoxides, the main substrates for the synthesis of VOO volatile compounds. Recombinant Oep2LOX1 displayed a low thermal stability, which suggests a weak actuation during the oil extraction process considering the current thermal conditions of this industrial process. In addition, recombinant OepHPL could be identified as the HPL activity in crude preparations. The thermal stability was the highest among the recombinant proteins studied, which suggests that HPL activity is not a limiting factor for the synthesis of VOO volatile compounds. 相似文献
982.
Marín-Benito JM Andrades MS Sánchez-Martín MJ Rodríguez-Cruz MS 《Journal of agricultural and food chemistry》2012,60(28):6936-6945
The degradation kinetics and formation of metabolites for fungicides of different chemical classes (iprovalicarb, metalaxyl, penconazole, and pyrimethanil) and determination of bound residues for metalaxyl and penconazole were studied in both an unamended vineyard soil and in the same soil amended with two spent mushroom substrates (composted (C-SMS1) and fresh (F-SMS2)). The degradation kinetics was fitted to single first-order or first-order multicompartment patterns. Degradation rates decreased in C-SMS1-amended soils for all fungicides as compared to unamended soil, but in F-SMS2-amended soils, they decreased only for iprovalicarb and penconazole. The DT(50) values were higher by up to 1.8 (metalaxyl), 3.8 (pyrimethanil), 4.1 (iprovalicarb), and >1000 (penconazole) times in the soil plus C-SMS1 compared to those for soil plus F-SMS2 or unamended soil. The dissipation mechanism recorded the highest mineralization in the unamended soil for (14)C-metalaxyl and (14)C-penconazole, with the highest formation of nonextractable residues in the F-SMS2-amended soil for (14)C-metalaxyl. The results are consistent with (1) the chemical characteristics of each SMS (total and soluble organic carbon) controlling sorption and the bioavailability of fungicides and (2) the microbial activity of SMS-amended soils, which affects fungicide biodegradation. The findings of this work highlight the potential of SMS amendments with different characteristics to decrease or increase the degradation rate of a fungicide in a vineyard soil. 相似文献
983.
Federico Navarro-García Miguel Ángel Casermeiro Joshua P. Schimel 《Soil biology & biochemistry》2012,44(1):1-8
Rewetting events after a drought produce a pulse of soil respiration (the “Birch Effect”) that leads to a loss of carbon from soil, especially in Mediterranean ecosystems. Two main hypotheses have developed to explain the Birch effect: the “metabolic explanation”, based on the rapid consumption of intracellular osmolytes previously accumulated to survive to dry conditions, and the “physical explanation”, based on the consumption of carbon made accessible by physical destruction of internal structures of the soil.Here, we compared the respiration response of intact and crushed 9–4 mm aggregates from a California grassland soil under two different rewetting schemes: (1) successive short dry/wet events and (2) increased drought periods followed by a single rewetting. In intact aggregates, both microbial biomass and respiration rates were relatively stable through both experimental treatments. In crushed aggregates, through multiple short dry/wet cycles, both respiration rate and microbial biomass increased, while as drought length increased, biomass was unaffected but the magnitude of the following rewetting pulse increased. A mechanism that explains both these results is that crushing aggregates exposes occluded particular material that must be degraded into an immediately bioavailable form for microbes to take it up and metabolize it. Nitrification was generally higher in intact than crushed aggregates, suggesting the importance of physical association between nitrifiers and resources in regulating overall soil nitrification.This work suggests that physical processes are most important in driving respiration pulses through multiple rewetting cycles and that the physical association of organisms, substrates, and mineral particles are critical in controlling the functioning of the “microbial landscape”. 相似文献
984.
A. Pedescoll P. R. Knowles P. Davies J. García J. Puigagut 《Water, air, and soil pollution》2012,223(5):2263-2275
Clogging is the main operational problem associated with horizontal subsurface flow constructed wetlands (HSSF CWs). The measurement of saturated hydraulic conductivity has proven to be a suitable technique to assess clogging within HSSF CWs. The vertical and horizontal distribution of hydraulic conductivity was assessed in two full-scale HSSF CWs by using two different in situ permeameter methods (falling head (FH) and constant head (CH) methods). Horizontal hydraulic conductivity profiles showed that both methods are correlated by a power function (FH?=?CH0.7821, r 2?=?0.76) within the recorded range of hydraulic conductivities (0?C70?m/day). However, the FH method provided lower values of hydraulic conductivity than the CH method (one to three times lower). Despite discrepancies between the magnitudes of reported readings, the relative distribution of clogging obtained via both methods was similar. Therefore, both methods are useful when exploring the general distribution of clogging and, specially, the assessment of clogged areas originated from preferential flow paths within full-scale HSSF CWs. Discrepancy between methods (either in magnitude and pattern) aroused from the vertical hydraulic conductivity profiles under highly clogged conditions. It is believed this can be attributed to procedural differences between the methods, such as the method of permeameter insertion (twisting versus hammering). Results from both methods suggest that clogging develops along the shortest distance between water input and output. Results also evidence that the design and maintenance of inlet distributors and outlet collectors appear to have a great influence on the pattern of clogging, and hence the asset lifetime of HSSF CWs. 相似文献
985.
Carmen Fajardo Maria Ludovica Saccà Alicia Gibello María José Martinez-I?igo Mar Nande Carmen Lobo Margarita Martin 《Water, air, and soil pollution》2012,223(6):3385-3392
Fluorescence in situ hybridization (FISH) technique and qPCR analyses, targeting atz genes, were applied to detect the presence of simazine-degrading bacteria in an agricultural soil with a history of herbicide application. atzB-targeted bacteria detected by FISH represented 5% of total soil bacteria with potential capability to metabolize the herbicide. The soil natural attenuation capacity was confirmed in soil microcosms by measuring simazine degradation. Moreover, four bacterial strains were isolated from the soil and identified as Acinetobacter lwoffii, Pseudomonas putida, Rhizobium sp. and Pseudomonas sp. The isolates were able to grow using different s-triazine compounds and related metabolites as the sole carbon source. Growth parameters in presence of simazine were calculated using the Gompertz model. Rhizobium sp. showed the highest simazine degradation (71.2%) and mineralization (38.7%) rates, whereas the lowest values were found to A. lwoffii??50.4% of degradation and 22.4% of mineralization. Results from qPCR analyses of atzA, atzB and atzC genes revealed their presence in Rhizobium sp. and A. lwoffii, being atzB and atzC the most abundant functional genes. Rhizobium sp. showed a higher amount of the three biomarkers compared to A. lwoffii: the atzA, atzB and atzC gene copy number per microlitre were, respectively, 101, 102 and 103-fold higher in the former. Therefore the proposed molecular approaches based on the use of atz genes as biomarkers can be considered as useful tools to evaluate the presence and potential capability of degrading-s-triazines soil microorganisms. 相似文献
986.
Effects of Application of Organic and Inorganic Wastes for Restoration of Sulphur-Mine Soil 总被引:1,自引:0,他引:1
Raquel Melgar-Ramírez Verónica González Juan Antonio Sánchez Inés García 《Water, air, and soil pollution》2012,223(9):6123-6131
In situ remediation with waste material is an inexpensive method to reduce contaminant availability in polluted soil. The experiments were done to investigate the effects of possible in situ application of two different amendments: inorganic material (marble sludge) and organic material (horticultural waste compost) on chemical and biological properties of abandoned metalliferous mine wastes. The results show that the application of inorganic material raises the pH above neutrality and the combination of inorganic and organic material would produce the highest ratio of biological activity. The reductions of available Zn, Pb and As in lime, organic and lime/organic amendments were favoured by incubation time. However, available Cd content increased after 275?days of incubation, except the treatment with inorganic amendment. This work denoted that the application of lime with organic amendments has a better effect than the lime alone because the addition of both amendments improves both soil chemical and biological properties. 相似文献
987.
The immediate effect of low and high severity wildfires on the main soil properties, as well as their short‐ and medium‐term evolution under field conditions, was examined. The study was performed with three pine forest soils (two Leptosols and one Humic Cambisol, developed over granite and basic schist, respectively), located in the Atlantic humid temperate zone (Galicia, NW Spain). Samples were collected from the A‐horizon (0–5 cm depth) of the burnt and the corresponding unburnt soils, immediately and 3, 6 and 12 months after the wildfires. Most properties analysed exhibit immediate fire‐induced changes and different evolution depending on fire severity and soil type. In general, immediately after the fire pH and soil properties related to nutrients availability increased and cation exchange capacity decreased, whereas properties related to soil organic matter content (C, N, Fe and Al oxides) had a variable effect depending mainly on the soil studied; all these modifications were accentuated by fire severity. These effects were attenuated in the short term in the soil affected by a low severity wildfire, but they lasted for at least 1 year in the soils affected by high severity wildfires, particularly in the Leptosols. The results showed the importance of the fire as a disturbance agent in the dynamic of nutrients and soil organic matter that is directly related with soil quality in the Galician forest ecosystems. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
988.
989.
Sara Hueso Gennaro Brunetti Nicola Senesi Karam Farrag Teresa Hernández Carlos García 《Journal of Soils and Sediments》2012,12(4):503-512
Purpose
The objective of this work was to assess the effect of severe drought conditions on the characteristics of semiarid soil humic acids (HAs) as well as the effect of organic amendment on such changes. 相似文献990.
María Nazaret González-Alcaraz José álvarez-Rogel Antonio María-Cervantes Consuelo Egea Héctor Miguel Conesa 《Journal of Soils and Sediments》2012,12(9):1316-1326