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.

Marine microalgae are a promising feedstock for biofuel production given their high growth rates and biomass production together with cost reductions due to the use of seawater for culture preparation. However, different microalgae species produce different families of compounds. Some compounds could be used directly as fuels, while others require thermochemical processing to obtain quality biofuels. This work focuses on the characterization of three marine microalgae strains native in Mexico and reported for the first time. Ultrastructure and phylogenetic analysis, suggested that they belong to Nannochloropsis sp. (NSRE-1 and NSRE-2) and Nannochloris sp. (NRRE-1). The composition of their lipid fractions included hydrocarbons, triacylglycerides (TAGs), free fatty acids (FFAs) and terpenes. Based on theoretical estimations from TAG and FFA composition, the potential biodiesels were found to comply with six of the seven estimated properties (ASTM D6751 and EN 14214). On the other hand, hydrocarbons and terpenes synthesized by the strains have outstanding potential as precursors for the production of other renewable fuels, mainly green diesel and bio-jet fuel, which are “drop-in” fuels with quality properties similar to fossil fuels. The validity of this theoretical analysis was demonstrated for the oxygenates of strain NSRE-2, which were experimentally hydrodeoxygenated, obtaining a high-quality renewable diesel as the reaction product.

ABSTRACT. Bacteria oxidize organic matter and nutrients to produce electric energy in microbial fuel cells (MFC) -a technology of increasing importance because of its sustainability. To improve the performance of MFCs, it is necessary not only to gain a better understanding of MFC engineering designs, but also to improve the understanding of the composition of the microbial communities in MFCs. Fast and efficient DNA extraction protocols that are suitable for extracting diverse bacterial genomes are necessary to identify the bacterial diversity present in MFCs and to further monitor the dynamic changes of microbial communities. This study focused on testing different direct cell lysis protocols to extract DNA from a microbial sludge harvested DNA extraction of bacterial consortium in MFC from an MFC. The protocol that achieved the best results was based on a previous study, but was modified by eliminating a chaotropic salt and the special columns used for nucleic acid purification. The efficiency of this less expensive and more straightforward protocol was confirmed by PCR amplification of the 16S rRNA gene and denaturing gradient gel electrophoresis analysis, which confirmed the extraction of multiple genomes. The sequences of 10 clones revealed the presence of phyla, Proteobacteria, Firmicutes and Actinobacteria, comprising both Gramnegative and Gram-positive bacteria. Some of these bacteria were identified at the genus level, e.g., Clostridium, Pseudoxanthomonas, Tistrella, and Enterobacter; these genera have been described in active sludges from wastewater treatment, supporting the congruency of our results. Therefore, this protocol is a useful tool for analysis of the bacteria responsible for energy production in MFCs.

Several methodologies have been proposed to accelerate breeding programs in annatto (Bixa orellana L.). However, before implementing them it is important to understand the mating system in annatto, a tropical species that is highly commercial for its unique capability to produce bixin. This report focuses on estimating outcrossing rates in an open‐pollinated population of B. orellana by sequence‐related amplified polymorphism (SRAP). Eleven open‐pollinated progeny arrays of 10 individuals each were used for this determination. Sequence‐related amplified polymorphism data indicated a multilocus outcrossing rate (tm) of 0.748 and an average single‐locus outcrossing rate (ts) of 0.651. Outcrossing was predominant in the B. orelllana open‐pollinated population. The multilocus estimates differed from the single‐locus estimates (0.097), suggesting the existence of mating among relatives (biparental inbreeding). A Wright's fixation index (F) of 0.332, indicated high homozygosity in the progeny evaluated with random mating, suggesting low variability. Furthermore, we found that based on experimental analysis, a minimum of 40 markers was required to obtain tm estimates that stabilized at approximately 0.7, and did not change significantly with an increasing number of markers. The molecular markers SRAP detect adequate levels of polymorphism in B. orellana for evaluating the mating system of this species.