RESUMEN

The main challenge in treating aged soils highly contaminated with total petroleum hydrocarbons (TPH) is to enhance their bioavailability for microbial degradation. Hydrocarbons in soils undergo chemical changes that make them more resistant to biodegradation. This study investigates toluene's efficacy in enhancing the biodegradation of aged hydrocarbon-contaminated soil containing 292,000 mg TPH kg-1 dry soil. Toluene's effect was compared between solid phase (SOP) and slurry phase (SLP) treatments using a microbial consortium isolated from Cyperus laxus rhizosphere. TPH biodegradation and microbial respiration were measured, the latter to estimate the respiratory quotient (RQ, the ratio between moles of carbon dioxide released and moles of oxygen absorbed during respiration). Toluene significantly accelerated TPH biodegradation in both treatments, achieving ~ 30% higher removal than in a non-solvent control, possibly through improved bioavailability of aromatic compounds and other low molecular weight compounds. According to the RQ analysis, toluene enhanced microbial respiratory processes and hydrocarbon catabolism with higher hydrocarbon mineralization (RQ = ~ 0.5) in both SOP and SLP assays. Our results reveal toluene's potential to increase hydrocarbon availability and microbial degradation efficiency in aged contaminated soils; its use in various bioremediation techniques could be of broad applicability across diverse soil types and pollutants.

Asunto(s)

Biodegradación Ambiental , Hidrocarburos , Microbiología del Suelo , Contaminantes del Suelo , Tolueno , Tolueno/metabolismo , Contaminantes del Suelo/metabolismo , Hidrocarburos/metabolismo , Suelo/química , Cyperus/metabolismo , Rizosfera , Petróleo/metabolismo

RESUMEN

The aims of this work were to characterize the sorption and evaluate the inhibitory effect of octylphenol ethoxylate Triton X-100 (OPEOTx) on methanogenic and denitrifying sludges. According to Langmuir isotherm, maximums OPEOTx sorption values on methanogenic and denitrifying sludges were 60.70 mg (gVSS)-1 and 87.47 mg (gVSS)-1 respectively. The specific removal rate of chemical oxygen demand (rCOD) and the accumulated volume biogas (VBG) were used to evaluate the OPEOTx inhibitory effect on sludges. Experimental inhibition data were fitted to the models of non-competitive inhibition and modified Gompertz. Methanogenic sludges reached higher levels inhibition in the rCOD and biogas production potential Pmax (84.0 and 88.5%) comparing with denitrifying sludges (24.3 and 21.9%). Furthermore, in all OPEOTx concentrations, carbohydrates-proteins quotient value of the extracellular polymeric substances for the denitrifying sludges remained below respect to the same quotient in methanogenic sludges. The above contributes in part to explain the greater sorption capacity of the denitrifying sludges by OPEOTx and their granules resistance to be damaged by OPEOTx amphiphilic nature. The study gives insights to understand OPEOs interactions and their effects on methanogenic and denitrifying granular sludges.

Asunto(s)

Fenoles , Aguas del Alcantarillado , Reactores Biológicos , Octoxinol

RESUMEN

Tolerance index and phytoremediation factors of side oats grama (Bouteloua curtipendula) with recalcitrant polycyclic aromatic hydrocarbons (PAH) phenanthrene (PHE), pyrene (PYR), and benzo[a]pyrene (BaP) and the resulting impact on phenotypic response, were evaluated in sterile conditions with whole plant growing in test-tube cultures with MS medium with PAH and compared with Tall fescue (Festuca arundinacea), control for this study. PAH mixture of PHE, PYR and BaP (1:1:1 w/w/w) blended with Maya crude oil (1:1 w/w), final concentration of 1500 mg kg(-1) was used. After 40 days, BaP removal, in the presence of Maya crude was superior compared with PHE and PYR removal Although the presence of PAH negatively affects the phenotypic response of the plants; sterile conditions experiments were helpful to evaluate phytoremediation factors to elucidate some important questions regarding phytoremediation mechanisms; in this study, B. curtipendula was able to phytostabilizate BaP associated to a significant hydrocarbon removal (57.4%) with high root accumulation but attenuated transport to stems, here reported as translocation factor. To our knowledge, this is the first time that quantifiable phytoremediation factors were used to evaluate the tolerance and removal capacity of a native semi-arid climate plant which is probably able to phytoremediate hydrocarbon contaminated soils.

Asunto(s)

Poaceae/metabolismo , Hidrocarburos Policíclicos Aromáticos/metabolismo , Contaminantes del Suelo/metabolismo , Benzo(a)pireno/análisis , Benzo(a)pireno/metabolismo , Biodegradación Ambiental , Bioensayo , Transporte Biológico , Medios de Cultivo , Festuca/efectos de los fármacos , Festuca/crecimiento & desarrollo , Festuca/metabolismo , México , Petróleo , Fenantrenos/análisis , Fenantrenos/metabolismo , Fenotipo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Tallos de la Planta/efectos de los fármacos , Tallos de la Planta/crecimiento & desarrollo , Tallos de la Planta/metabolismo , Poaceae/efectos de los fármacos , Poaceae/crecimiento & desarrollo , Hidrocarburos Policíclicos Aromáticos/análisis , Pirenos/análisis , Pirenos/metabolismo , Contaminantes del Suelo/análisis , Factores de Tiempo

RESUMEN

El ácido jasmónico es un regulador del crecimiento de las plantas producidopor algas, microorganismos y plantas superiores, que participa en laactivación de mecanismos de defensa contra patógenos y ante la presenciade heridas en las plantas. En este trabajo se estudió la influencia de larelación carbono:nitrógeno (rC/N: 17, 35 y 70), el tipo de inóculo (esporas omicelio) y la adición de extracto de levadura al medio de cultivo en laproducción de ácido jasmónico por Botryodiplodia theobromae. Los estudiosrevelaron que la producción de ácido jasmónico es estimulada a una rC/N 17.La productividad del ácido jasmónico fue mayor para la inoculación conmicelio y la adición de extracto de levadura al medio de cultivo en 1,7 y 1,3veces, respectivamente(AU)

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Jasmonic acid is a native plant growth regulator produced by algae,microorganisms and higher plants. This regulator is involved in the activationof defence mechanisms against pathogens and wounding in plants. Studies concerning the effects of carbon: nitrogen ratio (C/Nr: 17, 35 and 70), type of inoculum (spores or mycelium) and the yeast extract addition in the media on jasmonic acid production by Botryodiplodia theobromae were evaluated. Jasmonic acid production was stimulated at the carbon: nitrogen ratio of 17. jasmonic acid productivity was higher in the media inoculated with mycelium and in the media with yeast extract 1,7 and 1,3 times, respectively(AU)

Asunto(s)

Carbono/administración & dosificación , Carbono/metabolismo , Mezclas Complejas/administración & dosificación , Mezclas Complejas/metabolismo , Ciclopentanos/metabolismo , Nitrógeno/administración & dosificación , Nitrógeno/metabolismo , Oxilipinas/metabolismo , Levaduras

RESUMEN

The effect of a hydrocarbon mixture (HCM) of three polycyclic aromatic hydrocarbons (PAH) and Maya crude oil on germination, growth and survival of four grasses (Bouteloua curtipendula, Cenchrus ciliaris, Echinochloa crusgalli and Rhynchelytrum repens) was studied and compared to a control (Festuca arundinacea) under in vitro conditions. The species were cultured on MS medium with different HCM initial concentrations. Germination was not affected for any assayed concentration; however, the length of the stems and roots decreased when HCM increased and the survival of the four species also diminished. Except for F. arundinacea, a direct link between hydrocarbon concentration and plant survival was observed. In vitro studies are clean and easy to handle techniques allowing isolation of the plant activity from that derived from associations with microorganisms in non-sterile cultures. To our knowledge, this is the first work towards phytoremediation assisted by in vitro plant cultivation.

Asunto(s)

Germinación , Hidrocarburos/administración & dosificación , Poaceae/crecimiento & desarrollo , Poaceae/fisiología , Contaminantes del Suelo/administración & dosificación , Medios de Cultivo , Especificidad de la Especie

RESUMEN

Hydrocarbon phytoremediation by Cyperus laxus Lam. growing on perlite and inoculated with hydrocarbon-degrading microorganisms was evaluated. Total petroleum hydrocarbons (TPH) were extracted from weathered soil (60.7 g of TPH kg(-1) of dry soil) and spiked on perlite at initial concentration of 5 g of TPH kg(-1) of dry perlite. Phenological characteristics, total microbial viable counts, hydrocarbon degraders and residual hydrocarbons were determined through 180 days of culture. Phenological characteristics of inoculated plants were improved as compared with non-inoculated plants: root biomass was 1.6 times greater, flowering time was reduced (13%), and the number of inflorescences was 1.5 times higher. The rhizospheric bacterial and fungi counts were higher for planted treatments (inoculated and not inoculated) than for unplanted pots. The maximum phytoremediation rate (0.51 mg of TPH g(-1) of dry plant d(-1)) for inoculated plants was reached at 60 days of culture, and was two times higher than for non-inoculated plants (55% TPH removal). Similar hydrocarbon phytoremediation extent values for inoculated (90%) and non-inoculated (85%) plants were obtained at 180 days of culture. The present study demonstrated that mutual benefits between C. laxus and inoculated hydrocarbon-degrading microorganisms are improved during phytoremediation. It is pertinent to note that this is the first report of hydrocarbon phytoremediation by Cyperus laxus Lam., a native plant growing in highly contaminated swamps.

Asunto(s)

Bacterias/metabolismo , Reactores Biológicos , Cyperus/metabolismo , Cyperus/microbiología , Hidrocarburos/metabolismo , Contaminantes del Suelo/metabolismo , Óxido de Aluminio , Biodegradación Ambiental , Biomasa , Recuento de Colonia Microbiana , Cyperus/fisiología , Hongos/metabolismo , Cromatografía de Gases y Espectrometría de Masas , México , Raíces de Plantas/crecimiento & desarrollo , Dióxido de Silicio , Espectroscopía Infrarroja por Transformada de Fourier

RESUMEN

Nonionic surfactants are used worldwide in various industrial and household applications. Since these compounds are used in aqueous solutions, they primarily enter the environment through sewage and industrial wastewater treatment plants. The objective of this work was to evaluate the inhibitory effect of Triton X-100, a commercial nonionic surfactant, on the anaerobic digestion of lactose. Thus non-ionic surfactants acts as a non-competitive inhibitor with K1 = 250 mgL-1 and a inhibition order of 2.4. Nonetheless if give enough time the sludge was able to degrade 79% of Triton at 0.1 gL-1 d-1 in a UASB reactor. An activity test of this sludge showed that Triton inhibited the acetogenic (both propionic and butyric) and acetoclastic activities, while there were high fermentative and hydrogenotrophic activities (80% and 95%, respectively).

Asunto(s)

Bacterias Anaerobias/fisiología , Detergentes/química , Octoxinol/química , Tensoactivos/metabolismo , Eliminación de Residuos Líquidos/métodos , Biodegradación Ambiental , Productos Domésticos , Lactosa/metabolismo , Purificación del Agua

Asunto(s)

DDT/metabolismo , Insecticidas/metabolismo , Microbiología del Suelo , Aerobiosis/efectos de los fármacos , Aerobiosis/fisiología , Anaerobiosis/efectos de los fármacos , Anaerobiosis/fisiología , Bacterias Aerobias/metabolismo , Bacterias Anaerobias/metabolismo , Biodegradación Ambiental/efectos de los fármacos , Dióxido de Carbono/metabolismo , DDT/análisis , Diclorodifenil Dicloroetileno/análisis , Diclorodifenildicloroetano/análisis , Cromatografía de Gases y Espectrometría de Masas , Metano/metabolismo , Phanerochaete/metabolismo

RESUMEN

A mathematical model was developed and tested to simulate the generation and transfer of heat in solid substrate fermentation (SSF). The experimental studies were realized in a 1-L static bioreactor packed with cassava wet meal and inoculated with Aspergillus niger. A simplified pseudohomogeneous monodimensional dynamic model was used for the energy balance. Kinetic equations taking into account biomass formation (logistic), sugar consumption (with maintenance), and carbon dioxide formation were used. Model verification was achieved by comparison of calculated and experimental temperatures. Heat transfer was evaluated by the estimation of Biot and Peclet heat dimensionless numbers 5-10 and 2550-2750, respectively. It was shown that conduction through the fermentation fixed bed was the main heat transfer resistance. This model intends to reach a better understanding of transport phenomena in SSF, a fact which could be used to evaluate various alternatives for temperature control of SSF, i.e., changing air flow rates and increasing water content. Dimensionless numbers could be used as scale-up criteria of large fermentors, since in those ratios are described the operating conditions, geometry, and size of the bioreactor. It could lead to improved solid reactor systems. The model can be used as a basis for automatic control of SSF for the production of valuable metabolites in static fermentors.