Tangerine (Citrus reticulata. CRP) and grapefruit (Citrus paradisi. CPP) pectins obtained by ultrasound-assisted extraction (UAE) and conventional extraction (CE) using citric acid were characterized to establish their potential uses as an alternative source of commercial pectin. The pectins obtained by UAE and CE presented a pseudoplastic fluid characteristic with shear thinning behavior, a high esterification degree (CRP 82.30-71.81% and CPP 84.25-72.15%) and were of commercial quality based on galacturonic acid content (CRP 76.03% and CPP 76.03-71.01%). CPP presented greater viscosimetric molecular weight than CRP. Meanwhile, CRP presented greater polyphenol and protein content with respect CPP. The functional properties were influenced by citrus source and extraction method. UAE favored greater yields in a shorter time (CPP: 26.05%, 30 min; CRP: 13.46%, 15 min) compared to CE. UAE combined with the use of citric acid offers an effective alternative for obtaining high-quality pectins with lower polluting effluent, time and energy requirements. Pectina cítrica obtenida por extracción asistida por ultrasonido: propiedades fisicoquímicas, estructurales, reológicas y funcionales RESUMEN Pectinas de mandarina (Citrus reticulata, PCR) y pomelo (Citrus paradisi, PCP) obtenidas vía extracción asistida por ultrasonido (EAU) y convencional (EC) con ácido cítrico fueron caracterizadas para establecer su potencial uso como una fuente alternativa de pectina comercial. Las pectinas obtenidas por EAU y EC presentaron características de fluido pseudoplástico con un comportamiento de adelgazamiento por cizalladura, alto grado de esterificación (CRP 82.30-71.81% and CPP 84.25-72.15%), y calidad comercial por el contenido de ácido galacturónico (CRP 76.03% and CPP 76.03-71.01%). PCP presentaron mayor peso molecular viscosimétrico comparado a PCR. Mientras PCR presentaron mayor contenido de polifenoles, y proteínas con respecto a PCP. Las propiedades funcionales fueron influenciadas por la fuente cítrica y el método de extracción. La EAU favoreció los mayores rendimientos a menor tiempo: PCP (26.05±0.49%, 30 min) y PCR (13.46±1.79%, 15 min) comparada con EC. La EAU representa una alternativa eficaz para la obtención de pectinas de alta calidad, con menores efluentes contaminantes, tiempo y energía.

BackgroundA laboratory-scale two-chamber microbial fuel cell employing an aerated cathode with no catalyst was inoculated with mixed inoculum and acetate as the carbon source.Electrochemical impedance spectroscopy (EIS) was used to study the behavior of the MFC during initial biofilm (week 1) and maximum power density (week 20). EIS were performed on the anode chamber, biofilm (without anolyte) and anolyte (without biofilm). Nyquist plots of the EIS data were fitted with two equivalent electrical circuits to estimate the contributions of intrinsic resistances to the overall internal MFC impedance at weeks 1 and 20, respectively.ResultsThe results showed that the system tended to increase power density from 15 ± 3 (week 1) to 100 ± 15 mW/m2 (week 20) and current density 211 ± 7 (week 1) to 347 ± 29 mA/m2 (week 20). The Samples were identified by pyrosequencing of the 16S rRNA gene and showed that initial inoculum (week 1) was constituted by Proteobacteria (40%), Bacteroidetes (22%) and Firmicutes (18%). At week 20, Proteobacterial species were predominant (60%) for electricity generation in the anode biofilm, being 51% Rhodopseudomonas palustris. Meanwhile on anolyte, Firmicutes phylum was predominant with Bacillus sp.This study proved that under the experimental conditions used there is an important contribution from the interaction of the biofilm and the anolyte on cell performance. Table 1 presents a summary of the specific influence of each element of the system under study.ConclusionsThe results showed certain members of the bacterial electrode community increased in relative abundance from the initial inoculum. For example, Proteobacterial species are important for electricity generation in the anode biofilms and Firmicutes phylum was predominant on anolyte to transfer electron.R1 is the same in the three systems and no variation is observed over time.The biofilm makes a significant contribution to the charge transfer processes at the electrode (R2 and Cdl) and, consequently, on the performance of the anode chamber.The biofilm can act as a barrier which reduces diffusion of the anolyte towards the electrode, all the while behaving like a porous material.The anolyte and its interaction with the biofilm exert a considerable influence on diffusion processes, given that it presents the highest values for Rd which increased at week 20.

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A reproducible method for extraction of high-quality genomic DNA (gDNA) suitable for application in several PCR-based methods was developed after modifications to the Dellaporta method. Changes to the extraction buffer include the use of a higher concentration of NaCl, substitution of β-mercaptoethanol with sodium-metabisulfite, and the use of polyethylene glycol for DNA precipitation. Compared to the original method and two other protocols tested, our improved protocol resulted in the isolation of a good yield and purity of gDNA. The content of extracted DNA was spectrophotometrically evaluated, and the quality was analyzed by Amplified Fragment Length Polymorphisms (AFLP). AFLP profiles of the DNA obtained with our protocol were comparable to those of a commercial kit for plant DNA extraction. The potential of this improved method relies on its successful use with different molecular markers using gDNA extracted from fresh and frozen tissues of a variety of vascular plants, including banana in this paper, and proven in wheat, guava, sugarcane, and bean, as well as from microalgae. Therefore, the new protocol is an adequate, convenient and economical choice for use and study of various fields of genomics.

Annatto (Bixa orellana L.) is the sole source of bixin, a seed-specific red apocarotenoid pigment used worldwide. Genetic improvement of annatto has focused on increasing bixin content as well as fostering traits that favor higher content such as pod indehiscence and flower color, among others. Eighty-seven samples collected from two separate important agricultural regions of the southeast of Mexico were characterized morphologically and analyzed genetically for the first time. The sequence-related amplified polymorphism was used for genetic analysis. Two-step cluster analysis of the individuals based on morphological traits produced three groups: one containing individuals with desired morphological characteristics and two others with complementary traits. Like the morphological analysis, the genetic analysis indicated high genetic variation, although the dendrogram based on Nei and Li's similarity coefficient showed them to be dispersed by collection site. However, calculated similarity index values indicated all individuals exhibited high genetic variation. The results are an important advance toward a more effective genetic improvement of annatto because crosses between the different morphological and/or genetic groups described here have the potential to produce a recombination of desired traits in hybrid offspring.