Papers by Sergio Alejandro Medina Moreno
Agradezco profundamente al Dr. Mariano Gutiérrez Rojas por su dirección en el presente proyecto. ... more Agradezco profundamente al Dr. Mariano Gutiérrez Rojas por su dirección en el presente proyecto. Este trabajo también se realizó con el apoyo económico del Consejo Nacional de Ciencia y Tecnología (CONACYT).
Journal of Environmental Management
We evaluated and characterized the biodegradation of the herbicide diuron in its commercial form ... more We evaluated and characterized the biodegradation of the herbicide diuron in its commercial form above its saturation concentration by Lysinibacillus fusiformis acclimatized by sequential batch culturing. Acclimatization was carried out in eight cycles in liquid culture, improving the capacity of L. fusiformis to remove diuron from 55.13 ± 1.3% in the first batch to 87.2 ± 0.11% in the eighth batch. Diuron biosorption was characterized with Langmuir and Freundlich isotherms, obtaining a maximum biosorption (qmax) of 0.00885 mg mg-1. In diuron biodegradation assays, a consumption substrate biomass yield (YSD/X) of 6.266 mg mg-1 was obtained, showing that biodegradation was the main mechanism in diuron removal. Diuron biodegradation by L. fusiformis was characterized by the Monod model, with a maximum specific growth rate (μmax) of 0.0245 h-1 and an affinity constant (KSD) of 344.09 mg L-1. A low accumulation of 3,4-dichloroaniline with the production of chloride ions indicated dechlorination when diuron was present at high concentrations. A phytotoxic assay conducted with Lactuca sativa showed that the toxicity of an effluent with diuron at 250 mg L-1 decreased when it was pretreated with acclimatized L. fusiformis. Acclimatization by sequential batch culturing improved the ability of L. fusiformis to biodegrade diuron at high concentrations, showing potential in the bioremediation of diuron-contaminated sites.
ECORFAN Journal-Ecuador, 2019
Poor agricultural practices have caused eroded soils, therefore alternatives are sought for the s... more Poor agricultural practices have caused eroded soils, therefore alternatives are sought for the solubilization and fixation of nutrients by mycorrhizal fungi, that grow on the plants roots forming a mutualist symbiosis. Therefore, in this work, Basidiomycetes fungi were isolated and those that are able to solubilizing phosphorus and nitrogen were selected for their inoculation in lettuce (Lactuca sativa), this is high consumption and fast growth vegetable. Five substrates (fertile soil, eroded soil, humus and horse manure) were studied with a not inoculated control, where the response variable was hypocotyl growth and the L. sativa radicle, measured every 24 hours for 30 days. It was observed that the HM3 fungi stimulated the highest growth of the plant in eroded soil, generating an alternative to agriculture and contributing to bioremediation and exploitation of damaged soils
Advances and Applications of Partitioning Bioreactors, 2019
Abstract Airlift bioreactor (ALB) is a multiphasic pneumatic system agitated with gas phase bubbl... more Abstract Airlift bioreactor (ALB) is a multiphasic pneumatic system agitated with gas phase bubbles that break toward the liquid phase, resulting in an isothermal expansion that keeps pseudo-homogeneity within the bioreactor. ALBs are extensively used in biotechnology. However, scarce information is available about environmental purposes, e.g., hydrocarbon biodegradation. This chapter is focused on describing the applicability of the airlift bioreactors for hydrocarbon biodegradation, considering some advantages and disadvantages; these could be evaluated by experimental way or via mathematical modeling and simulation. This chapter reviews: (i) an overview of hydrocarbon pollution, (ii) microbial uptake by direct contact and emulsified forms, (iii) bacterial uptake, (iv) fungal uptake, (v) airlift bioreactors as hydrocarbon remediation alternative, (vi) immobilized microorganisms in airlift bioreactors and (vii) mathematical modeling.
Revista Internacional de Contaminación Ambiental, 2017
Palabras clave: hongos, biorremediación, petróleo, consumo por contacto directo RESUMEN Se cultiv... more Palabras clave: hongos, biorremediación, petróleo, consumo por contacto directo RESUMEN Se cultivó en biorreactores de puente aéreo un consorcio microbiano para estudios ex situ. El consorcio fue obtenido de un cenote contaminado con fenantreno y naftaleno ubicado en la ciudad de Cancún, Quintana Roo, México. En este trabajo se mostró que el consorcio microbiano está también compuesto por hongos con al menos una especie de Cladosporium, además de las bacterias previamente identificadas en trabajos anteriores del grupo de investigación (Pseudomonas, Diplococcus y Enterobacter), por lo que se conforma así un consorcio mixto. Se modeló la cinética de crecimiento de biomasa fúngica utilizando tres modelos: Gompertz, de Von Bertalanffy y logístico para los datos obtenidos por espectrofotometría. Para todos los casos, Von Bertalanffy fue el modelo que se ajustó de manera sobresaliente a los valores experimentales (σ ≤ 0.4). El análisis por estereomicroscopía contribuyó a dar una explicación cualitativa de los mecanismos de asimilación de hidrocarburo en biomasa fúngica, al hacer evidente el contacto directo entre esta biomasa fúngica y el hidrocarburo. Finalmente, cultivos en cajas petri recubiertas con petróleo crudo maya corroboraron que la biomasa fúngica obtenida, produce alguna clase de hidrofobinas que permiten romper la tensión superficial entre la interfase hidrofílica/hidrofóbica, favoreciendo así el contacto con el sustrato y los microorganismos.
Materials and Technologies
The modeling of the growth kinetics of boride layers is an important tool determining suitable pr... more The modeling of the growth kinetics of boride layers is an important tool determining suitable process parameters for obtaining an adequate boride-layer thickness. In this study, a mathematical model of the growth kinetics of the Fe2B layers on gray cast iron was proposed for the powder-pack bonding. The kinetic-diffusion model considers the mass balance equation of the (Fe2B/Fe) interface with the purpose of determining the boron diffusion coefficients (D-Fe2B) in the Fe2B layers. The kinetic model was set for the Fe2B layer thickness, assuming that the growth of boride layers follows a parabolic growth law. The presented model can be used to predict the Fe2B layer thickness formed on gray cast iron during the powder-pack bonding. This process was carried out in the temperature range of 1123-1273 K with the exposure times ranging from 2 h to 8 h. The reliability of the technique used is compared with the experimental value for the Fe2B layer thickness obtained at 1253 K after 5 h o...
Revista Internacional De Contaminacion Ambiental, Aug 26, 2010
Palabras clave: biotensoactivos, Pseudomonas aeruginosa, ramnolípidos, tensión superficial RESUME... more Palabras clave: biotensoactivos, Pseudomonas aeruginosa, ramnolípidos, tensión superficial RESUMEN Los tensoactivos son moléculas anfifílicas con una porción hidrofílica y otra hidrofóbica; se localizan preferentemente en la interfase de fluidos con diferentes grados de polaridad como son la de aceite-agua o aire-agua. Las propiedades de un tensoactivo son caracterizadas principalmente por cuatro parámetros: concentración micelar crítica (CMC), número de agregación (n a), balance hidrofílico-lipofìlico (HLB) y punto de nube (PN). Estos parámetros indican el potencial del tensoactivo como agente emulsificante y de superficie, determinando su aplicación en diversas áreas, principalmente a nivel industrial y ambiental. Los tensoactivos son sintetizados vía química o biológica, denominando a los últimos biotensoactivos. Aunque una amplia gama de microorganismos son capaces de sintetizar biotensoactivos, las bacterias son las principales productoras. Los biotensoactivos integran una serie de compuestos cuya estructura puede ser simple-como los ramnolípidos, formados por mono y disacáridos unidos por enlaces glicosídicos a ácidos grasos hidroxilados-, o compleja, como el emulsán, biotensoactivo polimérico complejo que contiene unidades monoméricas de heteropolisacáridos enlazados a lípidos. Los biotensoactivos muestran ventajas sobre los de síntesis química debido a su compatibilidad con el ambiente, baja toxicidad y biodegradabilidad. Sin embargo, su principal desventaja son los elevados costos asociados a su producción. En la presente revisión se describen las propiedades químicas y microbiológicas de tensoactivos y biotensoactivos, así como las diferentes aplicaciones de los últimos, principalmente en el campo de la biorremediación. Además, se analiza la influencia de las principales variables de proceso sobre la producción de biotensoactivos, en particular de los ramnolípidos provenientes de Pseudomonas aeruginosa.
Processes
In some fermentation systems, whey components (lactose, proteins and minerals) can produce isopen... more In some fermentation systems, whey components (lactose, proteins and minerals) can produce isopentyl acetate (IA). An analysis of the best conditions for IA production with Kluyveromyces marxianus was developed in this work. The experiment design was two-factor and three-level design based on a response surface methodology (RSM) using Design-Expert® software. The analysis of anomeric protons by nuclear magnetic resonance (1H-NMR) showed 81.25% of β lactose content. This characteristic favored the production of IA. The maximum output (Mp) of IA, determined by gas chromatography, was 9.52 g/L (p < 0.05). The central composite design (CCD) was used to perform the factor analysis. Results showed that concentrations of 0.03 (g/L) ammonium sulphate and 0.3 (v/v) of isoamyl alcohol are the best conditions for a maximum rate of IA production. The production of IA can reduce the discharge of whey, allowing its reuse and revaluation.
Revista Mexicana de Fitopatología, Mexican Journal of Phytopathology, 2017
Se evaluó el efecto antifúngico de extractos de bulbos de Lilium híbrido L/A “Indian summer” sobr... more Se evaluó el efecto antifúngico de extractos de bulbos de Lilium híbrido L/A “Indian summer” sobre Fusarium oxysporum considerado como hongo patógeno que provoca daños severos en la agricultura y pérdidas económicas en diversos sectores de la industria. El extracto crudo se fraccionó en tres sub-extractos de acuerdo a la polaridad (polar, medianamente polar y no polar), los cuales se sometieron a bioensayos de inhibición siendo papa-dextrosa-agar (PDA) el tratamiento testigo. Las muestras que se trataron con el extracto medianamente polar presentaron la mayor inhibición, al disminuir la tasa de crecimiento en un 27%, en comparación al crecimiento micelial del testigo. Sin embargo, al comparar con extractos vegetales que reportaron bajo condiciones similares, se descarta como inhibidor del crecimiento y se considera como fungistático.
BioResources, 2014
Hydrolysis of corn leaf utilizing two treatment sequences was carried out in this study. The firs... more Hydrolysis of corn leaf utilizing two treatment sequences was carried out in this study. The first treatment was chemical and involved subjecting the corn leaf to an alkaline pre-treatment and then to a smooth acid hydrolysis. The second consisted of biological delignification using the strain Trametes sp. 44 H88, followed by enzymatic hydrolysis using the enzymatic extract produced by Trichoderma sp. H88. The ligninolytic extract produced by Trametes sp. 44 H88 was used to detoxify the hydrolyzate. The results indicate that biological pre-treatment with delignification is more favorable and improves the subsequent hydrolysis, regardless of whether the hydrolysis is chemical or biological. The chemical treatment sequence obtained 80% conversion of monosaccharides, while the biological treatment sequence resulted in a 87% conversion rate. Finally, the use of the ligninolytic extract for the dephenolization of the hydrolyzate reduced the presence of compounds of phenolic origin by 23%.
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Papers by Sergio Alejandro Medina Moreno