RESUMEN
Clostridium autoethanogenum can to convert waste gases (CO2, CO, H2) and xylose from hydrolyzed biomass into acetate, lactate, formate, ethanol and 2,3-butanediol, being a candidate for the transformation of waste streams of lignocellulosic biorefineries. Electro-fermentation (EF) modify the pattern of traditional fermentations resulting in improved product yields as has been shown when using Clostridium strains. The aim of this work was to evaluate the influence of pH on microbial growth and product distribution during fermentation and EF of xylose by C. autoethanogenum DSM10061. Fermentation and EF were carried out in a H-type reactor at three controlled pH: 5.0, 5.5 and 5.8, and at a fixed potential of -600 mV (versus Ag/AgCl) in the EF. The experiments showed that maximum biomass concentration increased as the pH increased in fermentation and EF. In accordance with maximum biomass reached, the highest substrate conversion was observed at pH 5.8 for both systems, with 76.80 % in fermentation and 96.18 % in EF. Moreover, the highest concentrations of acetic acid (1.41 ± 0.07 g L-1) and ethanol (1.45 ± 0.15 g L-1) were obtained at the end of cultures in the EF at pH 5.8. The production of lactic and formic acid decreased by the application of the external potential regardless of the pH value, reaching the lowest productivity at pH 5.8. In contrast, the specific productivity of acetic acid and ethanol was lower in both fermentation and EF at the lowest pH. Furthermore, the presence of 0.06 g L-1 of 2,3-butanediol was only detected in EF at pH 5.8. The results revealed that EF modulated microbial metabolism, which can be explained by a possible increased generation of NADP+/NADPH cofactors, which would redirect the metabolic pathway to more reduced products.
Asunto(s)
Butileno Glicoles , Monóxido de Carbono , Xilosa , Fermentación , Xilosa/metabolismo , Clostridium/metabolismo , Redes y Vías Metabólicas , Ácido Acético/metabolismo , Etanol , Concentración de Iones de HidrógenoRESUMEN
BACKGROUND: Methanol can be effectively removed from air by biofiltration (Shareefdeen et al., 1993; Babbitt et al., 2009 [1,2]). However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms (Negruta et al., 2010 [3]), and it can be released out of the cell constituting a secondary emission. RESULTS: The total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m−3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1 . Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s. CONCLUSIONS: Formaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.
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Pichia/química , Metanol/química , Formaldehído/análisis , Volatilización , Filtros Biológicos , Biomasa , Reactores Biológicos , AmbienteRESUMEN
Background: Fermentation strategies for bioethanol production that use flocculating Saccharomyces cerevisiae yeast need to account for the mechanism by which inhibitory compounds, generated in the hydrolysis of lignocellulosic materials, are tolerated and detoxified by a yeast floc. Results: Diffusion coefficients and first-order kinetic bioconversion rate coefficients were measured for three fermentation inhibitory compounds (furfural, hydroxymethylfurfural, and vanillin) in self-aggregated flocs of S. cerevisiae NRRL Y-265. Thièle-type moduli and internal effectiveness factors were obtained by simulating a simple steady-state spherical floc model. Conclusions: The obtained values for the Thiéle moduli and internal effectiveness factors showed that the bioconversion rate of the inhibitory compounds is the dominant phenomenon over mass transfer inside the flocs.
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Saccharomyces cerevisiae/metabolismo , Biocombustibles , Levaduras , Benzaldehídos , Biodegradación Ambiental , Inactivación Metabólica , Difusión , Floculación , Furaldehído/análogos & derivadosRESUMEN
Background: Methanol can be effectively removed from air by biofiltration. However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms, and it can be released out of the cell constituting a secondary emission. Results: The total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m− 3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1 . Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s. Conclusions: Formaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment
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Pichia/metabolismo , Metanol/metabolismo , Formaldehído/metabolismo , Biomasa , Contaminantes Atmosféricos , Ambiente , FiltraciónRESUMEN
In this work, three Clostridium strains were tested for butanol production from Agave lechuguilla hydrolysates to select one for co-culturing. The agave hydrolysates medium was supplemented with nutrients and reducing agents to promote anaerobiosis. Clostridium acetobutylicum ATCC 824 had the highest butanol production (6.04â¯g/L) and was selected for further analyses. In the co-culture process, Bacillus subtilis CDBB 555 was used to deplete oxygen and achieve anaerobic conditions required for butanol production. The co-culture was prepared with C. acetobutylicum and B. subtilis without anaerobic pretreatment. Butanol production in co-culture from agave hydrolysates was compared with experiments using synthetic medium with glucose and a pure culture of C. acetobutylicum. The maximum butanol concentration obtained was 8.28â¯g/L in the co-cultured hydrolysate medium. Results obtained in the present work demonstrated that agave hydrolysates have the potential for butanol production using a co-culture of B. subtilis and C. acetobutylicum without anaerobic pretreatment.
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Agave/metabolismo , Bacillus subtilis/metabolismo , Butanoles/metabolismo , Clostridium acetobutylicum/metabolismo , Anaerobiosis , Técnicas de Cocultivo , FermentaciónRESUMEN
Background: Trimethylamine (TMA) is the main responsible for the odor associated with rotting fish and other annoying odors generated in many industrial activities. Biofiltration has proved to be efficient for treating odorous gaseous emissions. The main objective of this work was to determine the removal capacity of TMA of a biotrickling filter inoculated with Aminobacter aminovorans and to evaluate the effect of H2S on its performance. Results: The maximumspecific growth rate ofA. aminovorans in a liquid culture was 0.15 h -1 , witha TMAto biomass yield of 0.10 (g g -1) and a specific consumption rate of 0.062 g·g-1·h-1 . The initial specific consumption rate of TMA was highly influenced by the presence of H2S in liquid culture at concentrations of 20 and 69 ppm in heading space oftheflasks.ABTF inoculatedwithA. aminovorans showedremoval efficiencieshigher than98%ina range ofloading rate of 0.2 to 8 g·m-3·h-1 at empty bed residence time (EBRT) of 85 and 180 s. No effect on the elimination capacity and efficiency was detected when H2S was added at 20 and 50 ppm to the inlet gaseous emission, though the fraction of A. aminovorans measured by qPCR in the biofilm decreased. Conclusions:Abiotrickling filter inoculated with A. aminovorans can remove efficiently the TMA in a gaseous stream. The elimination capacity of TMA can be negatively affected by H2S, but its effect is not notorious when it is forming part of a biofilm, due to its high specific consumption rate of TMA.
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Alphaproteobacteria/metabolismo , Sulfuro de Hidrógeno , Metilaminas/metabolismo , Desodorización/métodos , Reactores Biológicos , Filtración , PecesRESUMEN
Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are important indoor contaminants. Their hydrophobic nature hinders the possibility of biological abatement using biofiltration. Our aim was to establish whether the use of a consortium of Fusarium solani and Rhodococcus erythropolis shows an improved performance (in terms of mineralization rate and extent) towards the degradation of formaldehyde, as a slightly polar VOC; toluene, as hydrophobic VOC; and benzo[α]pyrene (BaP) as PAH at low concentrations compared to a single-species biofilm in serum bottles with vermiculite as solid support to mimic a biofilter and to relate the possible improvements with the surface hydrophobicity and partition coefficient of the biomass at three different temperatures. Results showed that the hydrophobicity of the surface of the biofilms was affected by the hydrophobicity of the carbon source in F. solani but it did not change in R. erythropolis. Similarly, the partition coefficients of toluene and BaP in F. solani biomass (both as pure culture and consortium) show a reduction of up to 38 times compared to its value in water, whereas this reduction was only 1.5 times in presence of R. erythropolis. Despite that increments in the accumulated CO2 and its production rate were found when F. solani or the consortium was used, the mineralization extent of toluene was below 25%. Regarding BaP degradation, the higher CO2 production rates and percent yields were obtained when a consortium of F. solani and R. erythropolis was used, despite a pure culture of R. erythropolis exhibits poor mineralization of BaP.
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Benzo(a)pireno/metabolismo , Biodegradación Ambiental , Formaldehído/metabolismo , Fusarium/metabolismo , Rhodococcus/metabolismo , Tolueno/metabolismo , Contaminación del Aire Interior/prevención & control , Biomasa , Filtración/instrumentación , Consorcios Microbianos/fisiología , Hidrocarburos Policíclicos Aromáticos/metabolismo , Compuestos Orgánicos Volátiles/metabolismoRESUMEN
The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ethanol yields is strongly dependent on aeration conditions. It has been reported that changes in the availability of NAD(H/+) cofactors can improve fermentation in some microorganisms. In this work genome-scale metabolic modeling and phenotypic phase plane analysis were used to characterize metabolic response on a range of uptake rates. Sensitivity analysis was used to assess the effect of ARC on ethanol production indicating that modifying ARC by inhibiting the respiratory chain ethanol production can be improved. It was shown experimentally in batch culture using Rotenone as an inhibitor of the mitochondrial NADH dehydrogenase complex I (CINADH), increasing ethanol yield by 18%. Furthermore, trajectories for uptakes rates, specific productivity and specific growth rate were determined by modeling the batch culture, to calculate ARC associated to the addition of CINADH inhibitor. Results showed that the increment in ethanol production via respiratory inhibition is due to excess in ARC, which generates an increase in ethanol production. Thus ethanol production improvement could be predicted by a change in ARC.
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Fermentación/genética , Pichia/metabolismo , Técnicas de Cultivo Celular por Lotes/métodos , Etanol , Análisis de Flujos Metabólicos/métodos , Modelos Biológicos , Oxidación-Reducción , Fenotipo , Pichia/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Xilosa/metabolismoRESUMEN
Background: Sulphur-oxidizing microorganisms are widely used in the biofiltration of total reduced sulphur compounds (odorous and neurotoxic) produced by industries such as the cellulose and petrochemical industries, which include high-temperature process steps. Some hyperthermophilic microorganisms have the capability to oxidize these compounds at high temperatures (N60°C), and archaea of this group, for example, Sulfolobus metallicus, are commonly used in biofiltration technology. Results: In this study, a hyperthermophilic sulphur-oxidizing strain of archaea was isolated from a hot spring (Chillán, Chile) and designated as M1. It was identified as archaea of the genus Sulfolobus (99% homology with S. solfataricus 16S rDNA). Biofilms of this culture grown on polyethylene rings showed an elemental sulphur oxidation rate of 95.15 ± 15.39 mg S l-1 d-1, higher than the rate exhibited by the biofilm of the sulphur-oxidizing archaea S. metallicus (56.8 ± 10.91 mg l-1 d-1). Conclusions: The results suggest that the culture M1 is useful for the biofiltration of total reduced sulphur gases at high temperatures and for other biotechnological applications.
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Sulfuros/metabolismo , Archaea/metabolismo , Biopelículas , Oxidación-Reducción , Filogenia , Reacción en Cadena de la Polimerasa , Sulfolobus , Archaea/aislamiento & purificación , Archaea/genética , Polietileno , Manantiales de Aguas Termales/microbiología , Electroforesis , Filtración , Extremófilos , CalorRESUMEN
The oxidation of methane (CH4) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH4 that cannot be used as a source of energy. However, conventional biofilters utilize organic packing materials that have a short lifespan, clogging problems, and are commonly inoculated with non-specific microorganisms leading to unpredictable CH4 elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH4 in two biotrickling filters (BTFs) packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp., in order to determine EC and CO2 production (pCO2) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH4. A dynamic mathematical model that describes the CH4 abatement in the BTFs was developed and validated using mass transfer and kinetic parameters estimated independently. The results showed that EC and pCO2 of the BTFs are not identical but very similar for all the conditions tested. The use of specific inoculum has shown a faster startup and higher EC per unit area (0.019 gCH4 m-2 h-1) in comparison to most of the previous studies at the same CH4 load rate (23.2 gCH4 m-3 h-1). Global mass balance showed that the maximum reduction of CO2 equivalents was 98.5 gCO2eq m-3 h-1. The developed model satisfactorily described CH4 abatement in BTFs for a wide range of conditions.
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Reactores Biológicos , Restauración y Remediación Ambiental/métodos , Metano/metabolismo , Methylococcaceae/metabolismo , Methylocystaceae/metabolismo , Biodegradación Ambiental , Filtración , Gases de Efecto Invernadero/metabolismo , Modelos Biológicos , Oxidación-ReducciónRESUMEN
The biological production of butanol has become an important research field and thanks to genome sequencing and annotation; genome-scale metabolic reconstructions have been developed for several Clostridium species. This work makes use of the iCAC490 model of Clostridium acetobutylicum ATCC 824 to analyze its metabolic capabilities and response to an external electron supply through a constraint-based approach using the Constraint-Based Reconstruction Analysis Toolbox. Several analyses were conducted, which included sensitivity, production envelope, and phenotypic phase planes. The model showed that the use of an external electron supply, which acts as co-reducing agent along with glucose-derived reducing power (electrofermentation), results in an increase in the butanol-specific productivity. However, a proportional increase in the butyrate uptake flux is required. Besides, the uptake of external butyrate leads to the coupling of butanol production and growth, which coincides with results reported in literature. Phenotypic phase planes showed that the reducing capacity becomes more limiting for growth at high butyrate uptake fluxes. An electron uptake flux allows the metabolism to reach the growth optimality line. Although the maximum butanol flux does not coincide with the growth optimality line, a butyrate uptake combined with an electron uptake flux would result in an increased butanol volumetric productivity, being a potential strategy to optimize the production of butanol by C. acetobutylicum ATCC 824.
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Clostridium acetobutylicum/metabolismo , Simulación por Computador , Electrones , Modelos BiológicosRESUMEN
Gasoline is the second most consumed fuel in Chile, accounting for 34% of the total fuel consumption in transportation related activities in 2012. Chilean refineries process more than 97% of the total gasoline commercialized in the national market. When it comes to evaluating the environmental profile of a Chilean process or product, the analysis should consider the characteristics of the Chilean scenario for fuel production and use. Therefore, the identification of the environmental impacts of gasoline production turns to be very relevant for the determination of the associated environmental impacts. For this purpose, Life Cycle Assessment has been selected as a useful methodology to assess the ecological burdens derived from fuel-based systems. In this case study, five subsystems were considered under a "well-to-wheel" analysis: crude oil extraction, gasoline importation, refinery, gasoline storage and distribution/use. The distance of 1 km driven by a middle size passenger car was chosen as functional unit. Moreover, volume, economic and energy-based allocations were also considered in a further sensitivity analysis. According to the results, the main hotspots were the refining activities as well as the tailpipe emissions from car use. When detailing by impact category, climate change was mainly affected by the combustion emissions derived from the gasoline use and refining activities. Refinery was also remarkable in toxicity related categories due to heavy metals emissions. In ozone layer and mineral depletion, transport activities played an important role. Refinery was also predominant in photochemical oxidation and water depletion. In terms of terrestrial acidification and marine eutrophication, the combustion emissions from gasoline use accounted for large contributions. This study provides real inventory data for the Chilean case study and the environmental results give insight into their influence of the assessment of products and processes in the country. Moreover, they could be compared with production and distribution schemes in other regions.
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Monitoreo del Ambiente , Industria Procesadora y de Extracción/estadística & datos numéricos , Gasolina , Dióxido de Carbono/análisis , Chile , Cambio Climático , Efecto Invernadero , Petróleo , Emisiones de Vehículos/análisisRESUMEN
Scheffersomyces stipitis is a yeast able to ferment pentoses to ethanol, unlike Saccharomyces cerevisiae, it does not present the so-called overflow phenomenon. Metabolic features characterizing the presence or not of this phenomenon have not been fully elucidated. This work proposes that genome-scale metabolic response to variations in NAD(H/(+)) availability characterizes fermentative behavior in both yeasts. Thus, differentiating features in S. stipitis and S. cerevisiae were determined analyzing growth sensitivity response to changes in available reducing capacity in relation to ethanol production capacity and overall metabolic flux span. Using genome-scale constraint-based metabolic models, phenotypic phase planes and shadow price analyses, an excess of available reducing capacity for growth was found in S. cerevisiae at every metabolic phenotype where growth is limited by oxygen uptake, while in S. stipitis this was observed only for a subset of those phenotypes. Moreover, by using flux variability analysis, an increased metabolic flux span was found in S. cerevisiae at growth limited by oxygen uptake, while in S. stipitis flux span was invariant. Therefore, each yeast can be characterized by a significantly different metabolic response and flux span when growth is limited by oxygen uptake, both features suggesting a higher metabolic flexibility in S. cerevisiae. By applying an optimization-based approach on the genome-scale models, three single reaction deletions were found to generate in S. stipitis the reducing capacity availability pattern found in S. cerevisiae, two of them correspond to reactions involved in the overflow phenomenon. These results show a close relationship between the growth sensitivity response given by the metabolic network and fermentative behavior.
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Fermentación , Genoma Fúngico , NAD/metabolismo , Saccharomyces cerevisiae/fisiología , Reactores Biológicos , Simulación por Computador , Etanol/metabolismo , Modelos Biológicos , Fenotipo , Especificidad de la EspecieRESUMEN
Oxidation of methane by methanotrophs, Methylomicrobium album and Methylocystis sp., was measured at several initial concentrations of H2S and NH3 in the headspace of stoppered flasks, at the same initial concentration of methane as sole carbon and energy source: 15 % (v/v). No effect was observed at 0.01 % (v/v) H2S and 0.025 % (v/v) NH3 in gas phase but over 0.05 and 0.025 % (v/v), respectively, they inhibited the oxidation of methane. The effect of H2S was stronger in Methylocystis sp. and both microorganisms were similarly affected by NH3. Depending on their concentrations in gas phase, H2S and NH3 can thus affect the rate of oxidation of methane and biomass growth of both methanotrophs.
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Amoníaco/farmacología , Sulfuro de Hidrógeno/farmacología , Metano/análisis , Metano/metabolismo , Methylococcaceae/metabolismo , Methylocystaceae/metabolismo , Amoníaco/metabolismo , Dióxido de Carbono , Sulfuro de Hidrógeno/metabolismo , Concentración de Iones de Hidrógeno , Metano/química , Oxidación-Reducción/efectos de los fármacosRESUMEN
This work proposes a decision-making framework for the selection of processes and unit operations for lignocellulosic bioethanol production. Process alternatives are described by its capital and operating expenditures, its contribution to process yield and technological availability information. A case study in second generation ethanol production using Eucalyptus globulus as raw material is presented to test the developed process synthesis tool. Results indicate that production cost does not necessarily decrease when yield increases. Hence, optimal processes can be found at the inflexion point of total costs and yield. The developed process synthesis tool provides results with an affordable computational cost, existing optimization tools and an easy-to-upgrade description of the process alternatives. These features made this tool suitable for process screening when incomplete information regarding process alternatives is available.
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Biocombustibles , Biotecnología/métodos , Etanol/metabolismo , Lignina/química , Biocombustibles/economía , Biotecnología/economía , Costos y Análisis de Costo , Etanol/economía , Eucalyptus/química , Modelos Lineales , Dinámicas no LinealesRESUMEN
Background: Bioethanol is produced mainly from sugar cane and corn. In the last years it has been subject of debate due to the effects in food prices and land use change. The use of lignocellulosic materials for bioethanol production, such as agroindustry, forestry and municipal residues, wood or dendroenergetic species, has been proposed as a sustainable way for producing this biofuel. The design of a sustainable process for producing bioethanol requires a methodological approach whereby economical, environmental and social criteria are systematically integrated from the early stages of process design. Results: Until now a methodology for guiding the design of a sustainable process for bioethanol production is not available, and there are just a few studies on this subject. Moreover, with the recent global concerns on climate change, developed technologies have been confronted with additional requirements to validate their sustainability. In this sense, the inclusion of sustainability criteria on process design becomes necessary for defining a systematic methodology to select the most appropriate operations in the process stages to achieve a sustainable bioethanol production. Conclusions: A description of the stages for the production of bioethanol from lignocellulosic materials is provided in this review and the main findings in relation to the more important sustainability indicators are presented.
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Etanol/metabolismo , Biocombustibles/análisis , Lignina/metabolismo , Estadios del Ciclo de VidaRESUMEN
Mixtures of volatile reduced sulphur compounds (VRSCs) like hydrogen sulphide (H(2)S), methylmercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) are found in gaseous emissions of several industrial activities creating nuisance in the surroundings. Hydrogen sulphide (H(2)S) decreases the removal efficiency of volatile reduced sulphur compounds (VRSCs) in biofilters but the kinetics of this effect is still unknown. Kinetic expressions that represent the rate of bio-oxidation of H(2)S, MM, DMS and DMDS are proposed. In order to observe and quantify this effect, equimolar mixtures of MM, DMS and DMDS were fed into a biotrickling filter inoculated with Thiobacillus thioparus at different H(2)S loads. Experimental results shown a good agreement with the simulations generated by the model considering the kinetic equations proposed. The estimated kinetic constants show that H(2)S and MM have a significant inhibitory effect on the bio-oxidation of DMS and DMDS, having the H(2)S the higher effect.
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Reactores Biológicos , Filtración/instrumentación , Compuestos de Azufre/aislamiento & purificación , Biodegradación Ambiental , Simulación por Computador , Disulfuros/aislamiento & purificación , Sulfuro de Hidrógeno/aislamiento & purificación , Cinética , Oxidación-Reducción , Análisis de Regresión , Compuestos de Sulfhidrilo/aislamiento & purificación , Sulfuros/aislamiento & purificación , Thiobacillus/metabolismo , VolatilizaciónRESUMEN
Background: The behaviour of two biotrickling filters connected in serie (BTF) inoculated with Acidithiobacillus thiooxidans and Thiobacillus thioparus, biodegrading hydrogen sulphide (H2S) and dimethyl sulphide (DMS) simultaneously were studied. A model which considers gas to liquid mass transfer and biooxidation in the biofilm attached to the support is developed. Additionally, a fixed bed biotrickling filter where the microorganism is immobilized in a biofilm which degrades a mixture of H2S and DMS is implemented. Validation of the model was carried out using experimental data obtained at different H2S and DMS loads. Results: The inhibitory effect caused by the presence of H2S on the DMS is observed, which is evidenced by the decrease of the DMS removal efficiency from 80 to 27 percent, due to the preference that T. thioparus has by simple metabolism. H2S is not affected by the DMS, with removal efficiencies of 95 to 97 percent, but it decreases at high concentrations of the compound, due to the inhibition of metabolism by high H2S input loads. The model which describes the BFT fits successfully with the experimental results and it has a high sensitivity to inhibition parameters. Conclusion: It is shown that the microorganism has a high affinity for H2S, producing substrate inhibition when the concentration is high. The H2S is able to inhibit the DMS biooxidation, whereas the DMS does not affect the H2S biooxidation.
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Filtración , Sulfuro de Hidrógeno , Modelos Teóricos , Sulfuros , Thiobacillus , Acidithiobacillus thiooxidansRESUMEN
Sulfolobus metallicus is a hyperthermophilic and chemolithoautotrophic archaeon that uses elemental sulfur as an energy source. Its ability to oxidize H(2)S was measured either in the presence or absence of elemental sulphur, showing its ability for using both as an energy source. A biotrickling filter was set up and a biofilm of S. metallicus was established over the support. The maximum removal capacity of the biotrickling filter reached at 55°C was 40 g S/m(3)h for input loads higher than 70 g S/m(3)h. Thus, S. metallicus can be used in a biofiltration system for the treatment of waste gas emissions at high temperatures contaminated with H(2)S.
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Sulfuro de Hidrógeno/metabolismo , Sulfolobus/metabolismo , Biopelículas/crecimiento & desarrollo , Filtración/métodos , Oxidación-Reducción , Sulfolobus/crecimiento & desarrollo , Sulfolobus/fisiología , Azufre/metabolismo , Temperatura , Purificación del Agua/métodosRESUMEN
Sulphur Oxidizing Bacteria (SOB) is a group of microorganisms widely used for the biofiltration of Total Reduced Sulphur compounds (TRS). TRS are bad smelling compounds with neurotoxic activity which are produced by different industries (cellulose, petrochemical). Thiobacillus thioparus has the capability to oxidize organic TRS, and strains of this bacterium are commonly used for TRS biofiltration technology. In this study, two thiosulphate oxidizing strains were isolated from a petrochemical plant (ENAP BioBio, Chile). They were subjected to molecular analysis by real time PCR using specific primers for T. thioparus. rDNA16S were sequenced using universal primers and their corresponding thiosulphate activities were compared with the reference strain T. thioparus ATCC 10801 in batch standard conditions. Real time PCR and 16S rDNA sequencing showed that one of the isolated strains belonged to the Thiobacillus branch. This strain degrades thiosulphate with a similar activity profile to that shown by the ATCC 10801 strain, but with less growth, making it useful in biofiltration.