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Mexico City, Mexico

Garcia-Canedo J.C.,CINVESTAV | Cristiani-Urbina E.,ENCB IPN | Flores-Ortiz C.M.,National Autonomous University of Mexico | Ponce-Noyola T.,CINVESTAV | And 2 more authors.
Algal Research | Year: 2016

The microalga Scenedesmus incrassatulus was cultivated in batch and fed-batch culture modes under three different nitrogen concentrations (N). Considering that nitrogen limitation results in carotenoid accumulation, main objectives of this work were to assess carotenoid concentration and the following fluorescence parameters: maximum photosynthetic efficiency (Fv/Fm), operational photosynthetic efficiency (Fq'/Fm') and the non-photochemical quenching (NPQ) at different N concentrations in the culture media, using batch and fed-batch culture modes. In all treatments, carotenoid concentration reached maximal level when N concentration in the medium was almost completely depleted. Carotenoid concentrations in fed-batch treatments were up to 3 times higher than batch culture treatments. Maximum dry weight of 4.05±0.04gL-1 and cell concentration of 8.24×107cellmL-1 was obtained using the higher N concentration in fed-batch, these values were approximately 3 times higher than the obtained in batch culture. Fv/Fm showed the highest magnitude when the initial N concentration in the culture medium was higher, for both culture modes. Results showed that the fed-batch culture of S. incrassatulus promotes a higher Fv/Fm than batch culture (up to 0.78). The application of fed-batch culture had the effect of stabilizing the values of Fv/Fm during feeding period. In all fed-batch treatments the maximum Fq'/Fm' was detected during the feeding period, which had maximum values ranging from 0.47-0.58. In fed-batch culture mode NPQ showed no direct relationship with total carotenoid concentration. ETR was higher in fed batch than in batch cultivation. In batch cultivation mode ETR had values ranging from 2 to 56μmolelectronsm-2s-1. ETR increased 6 fold in fed-batch cultivation when irradiance was increased, having values up to 610μmolelectronsm-2s-1. A good cultivation strategy for biocompound production could be the use of fed batch cultivation aimed to return nutrients like nitrogen to its initial condition. © 2015 Elsevier B.V.. Source

Carrillo-Navas H.,National Autonomous University of Mexico | Cruz-Olivares J.,National Autonomous University of Mexico | Varela-Guerrero V.,National Autonomous University of Mexico | Alamilla-Beltran L.,ENCB IPN | And 2 more authors.
Carbohydrate Polymers | Year: 2012

Four water-in-oil-in water (W1/O/W2) double emulsions were made by adding the primary emulsion (W1/O) containing 74% (w/w) of chia essential oil, 6% (w/w) of ascorbic acid, and a 0.2 dispersed phase mass fraction (φW1/O) to aqueous solutions (W2) of mesquite gum (MG), maltodextrin DE-10 (MD) and whey protein concentrate (WPC) in different proportions (MG66-MD17-WPC17 and MG17-MD66-WPC17), and in a ratio of 1:2.12 and 1:4.12 W1/O to dry biopolymers blends solids. All the double emulsions showed type C morphologies and only slight changes in the volume-weighted mean diameter (d4,3) throughout the storage time, indicative of good stability, despite they presented bimodal size distributions, but the double emulsion formulated with a predominant proportion of MD and ratio 1:2.12 provided a higher stability against droplet coalescence. All the double emulsions displayed viscoelastic character dependent on frequency. © 2011 Elsevier Ltd. All rights reserved. Source

Morales-Pablo R.,ENCB IPN | de la Cruz A.,Colegio de Mexico | Leyva-Ruelas G.,National Autonomous University of Mexico | Ybarra-Moncada M.C.,National Autonomous University of Mexico
Revista Mexicana de Ingeniera Qumica | Year: 2012

In this study we determined the presence of Mesophilic Aerobic Bacteria (MAB), Total Coliform Bacteria (TCB) Fecal Coliform Bacteria (FCB) and the pathogen Salmonella. All of them were used as microbiological indicators to evaluate the best management practices and sanitation during the production process of raw goat's milk. Milk samples were collected aseptically, each week, from cattle ranches in Miravalles Oriental, Puebla. Ten out of fifty five farmers were randomly selected. They used two types of management; grazing and feedlot. The data collected were analyzed by Analysis of Variance, the Nonparametric test of Kruskal-Wallis and Cluster Analysis. All samples of raw goat milk met the standards 92/46/EEC and NMX-F-COFOCALEC-2007, with respect to the MAB. However, 50% of milk samples exceeded the microbiological limits established for TCB and FCB (NOM-243-SSA1-2010). These results were for milk samples from goats with feedlot management. In contrast, all samples successfully met these standards when collected from cattle herds that were grazed as did smaller heads. Finally, Salmonella was not detected in any sample of the raw milk. Source

Poggi-Varaldo H.M.,Environmental Biotechnology and Renewable Energies R and D Group | Munoz-Paez K.M.,Environmental Biotechnology and Renewable Energies R and D Group | Escamilla-Alvarado C.,Environmental Biotechnology and Renewable Energies R and D Group | Robledo-Narvaez P.N.,Environmental Biotechnology and Renewable Energies R and D Group | And 7 more authors.
Waste Management and Research | Year: 2014

Biohydrogen is a sustainable form of energy as it can be produced from organic waste through fermentation processes involving dark fermentation and photofermentation. Very often biohydrogen is included as a part of biorefinery approaches, which reclaim organic wastes that are abundant sources of renewable and low cost substrate that can be efficiently fermented by microorganisms. The aim of this work was to critically assess selected bioenergy alternatives from organic solid waste, such as biohydrogen and bioelectricity, to evaluate their relative advantages and disadvantages in the context of biorefineries, and nally to indicate the trends for future research and development. Biorefining is the sustainable processing of biomass into a spectrum of marketable products, which means: energy, materials, chemicals, food and feed. Dark fermentation of organic wastes could be the beach-head of complete biorefineries that generate biohydrogen as a first step and could significantly influence the future of solid waste management. Series systems show a better efficiency than one-stage process regarding substrate conversion to hydrogen and bioenergy. The dark fermentation also produces fermented by-products (fatty acids and solvents), so there is an opportunity for further combining with other processes that yield more bioenergy. Photoheterotrophic fermentation is one of them: photosynthetic heterotrophs, such as non-sulfur purple bacteria, can thrive on the simple organic substances produced in dark fermentation and light, to give more H2. Effluents from photoheterotrophic fermentation and digestates can be processed in microbial fuel cells for bioelectricity production and methanogenic digestion for methane generation, thus integrating a diverse block of bioenergies. Several digestates from bioenergies could be used for bioproducts generation, such as cellulolytic enzymes and saccharification processes, leading to ethanol fermentation (another bioenergy), thus completing the inverse cascade. Finally, biohydrogen, biomethane and bioelectricity could contribute to significant improvements for solid organic waste management in agricultural regions, as well as in urban areas. © The Author(s) 2014. Source

Peralta R.,Laboratorio Of Oncogenomica | Valdivia A.,Laboratorio Of Oncogenomica | Alvarado-Cabrero I.,Hospital de Oncologia | Gallegos F.,Servicio de Cabeza y Cuello | And 8 more authors.
Journal of Clinical Pathology | Year: 2012

Aims: The authors have previously reported that cellular retinol-binding protein 1 (CRBP1) gene gain and its expression correlated significantly with survival in laryngeal carcinoma patients. The authors hypothesised that inactivation of the CRBP1 gene through CpG methylation is associated with patient status and gene expression. In this work, the authors determine the expression and methylation status of the CRBP1 gene and its correlation with clinical variables of laryngeal carcinoma patients. Methods: The CRBP1 gene methylation promoter was assessed by methylation specific PCR analysis in tissue samples from larynx cancer specimens and its expression was assessed by immunohistochemistry on paraffin embedded tissue using tissue microarray. The results were then compared with the clinical pathological variables and outcome measures. The study included 46 samples from patients with non-metastatic squamous cell carcinoma of the larynx without any previous oncological treatments. Results: Lack of CRBP1 expression was seen in 17 of the 46 laryngeal carcinoma samples, while the remaining 29 samples showed increased expression. Significant associations were found between CRBP1 expression and methylation and patient status. There was a tendency for association in all clinical stages of the disease. CRBP1 gene expression and its unmethylated promoter correlated significantly with survival (p<0.05). Conclusions: An early event of larynx cancer could be CRBP1 expression related to unmethylation of the promoter region. These features could also be associated with good response and survival. The authors hypothesised that increased expression and unmethylated promoter of the CRBP1 gene could be considered as markers for larynx cancer. Source

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