Capacidad antifúngica de biopelículas de quitosán conteniendo bacterias ácido lácticas / Antifungal ability of chitosan biofilms containing lactic acid bacteria

INTRODUCCIÓN: Existen reportes del uso de biopelículas como soporte para la incorporación de microorganismos benéficos, sin embargo, son pocos los reportes donde se evalúe la capacidad antimicrobiana de las biopelículas conteniendo bacterias ácido lácticas (BAL). OBJETIVO: Optimizar los componentes de una biopelícula comestible basada en quitosán para conservar la viabilidad y la capacidad antifúngica de la BAL Lactobacillus plantarum CDBB-B-1091 durante 28 días. MÉTODOS: Bajo un diseño de 8 tratamientos tipo Plackett-Burman se evaluaron dos niveles de 7 factores (glucosa, lactosa, glicerol, almidón, humedad relativa del ambiente, pH, concentración de BAL). De los factores (componentes) que mostraron efecto, se optimizó la concentración mediante la metodología de superficie de respuesta basada en un arreglo de Box-Benhken. RESULTADOS: Se encontró que la concentración de células (A), concentración de almidón (B) y concentración de glucosa (C) son los componentes de la biopelícula más determinantes para mantener la viabilidad y la capacidad antifúngica contra el hongo fitopatógeno Colletotrichum gloeosporioides. Mediante análisis de superficie de respuesta se obtuvieron los valores óptimos para mantener la viabilidad de las bacterias por 28 días, siendo los valores de 7,009164 log UFC/g película para el factor A, 1,997712% para B y 0,10750016 M para el factor C. De acuerdo al análisis de la varianza la concentración de células el factor más influyente. Sin embargo, para la capacidad antifúngica solamente fue posible obtener inhibición del 100% con películas recién elaboradas, siendo para este día los valores óptimos de 8,9004 log (UFC/g) para el factor A, 2,0% para B y 0,0850143 M para C. CONCLUSIÓN: La capacidad antifúngica de las biopelículas conteniendo BAL fue decreciendo a medida que transcurrió el almacenamiento de las biopelículas. Aún con lo anterior, se proponen los modelos de regresión para predecir los valores de viabilidad y la capacidad antifúngica de biopelículas conteniendo la bacteria Lactobacillus plantarum CDBB-B-1091

INTRODUCTION: There are reports of the use of biofilms as a support for the incorporation of beneficial microorganisms, however, there are scarce the reports where the antimicrobial capacity of biofilms containing lactic acid bacteria (LAB) is evaluated. OBJECTIVE: Optimize the components of an edible biofilm based on chitosan to preserve the viability and antifungal capacity of the LAB Lactobacillus plantarum CDBB-B-1091 for 28 days. METHODS: Through a design Plackett-Burman of 8 treatments, two levels of 7 factors (componente) were evaluated (glucose, lactose, glycerol, starch, relative humidity, pH, BAL concentration). Of the factors that showed effect, the concentration was optimized using the response surface methodology based on a Box-Benhken arrangement. RESULTS: It was found that cell concentration (A), starch concentration (B) and glucose concentration (C) are the most determining biofilm components to maintain viability and antifungal ability against the phytopathogenic fungus Colletotrichum gloeosporioides. Optimal values were obtained by response surface analysis to maintain the viability of the bacteria for 28 days, the values being 7.009164 log CFU/g film for factor A, 1.997712% for B and 0.10750016 M for factor C. According to ANOVA the concentration of cells being the most influential factor. However, for the antifungal capacity it was only possible to obtain 100% inhibition with freshly made films, for this day the optimal values of 8.9004 log (CFU/g) for factor A, 2.0% for B and 0.0850143 M for C. CONCLUSION: The antifungal capacity of the biofilms containing BAL was decreasing as the storage of the biofilms passed. Even with the above, regression models are proposed to predict the viability values and the antifungal capacity of biofilms containing the bacterium Lactobacillus plantarum CDBB-B-1091

The metabolism and genetic regulation of lipids in the oleaginous yeast Yarrowia lipolytica.

The biotechnological potential of Yarrowia lipolytica, as a single cell oil-producing microorganism, is presented in this review. Although initially this yeast species was considered as a lipid-degrading, recently, it was reclassified as a lipid-producing microorganism, since it has been reported to be capable of accumulating diverse desirable fatty acids after metabolic pathway engineering. In the first part of the present document, a general revision of the oil metabolic pathways and the capacity of oil production in Y. lipolytica is presented. The single cell oil produced by these metabolic engineering strategies has been designed by optimization, introduction, or suppression of new pathways to increase yield on lipid production. Later on, the genetic regulation systems and the lipid composition generated by this yeast for industrial purposes are discussed. These lipids could be safely used in the chemical food and biofuel industries, due to their high proportion of oleic acid. This document emphasizes in the overviewing at Y. lipolytica as an ideal oil cell factory, and as an excellent model to produce single cell oil.

Isolation and identification of marine strains of Stenotrophomona maltophilia with high chitinolytic activity.

Chitin is the second most abundant organic compound in nature and represents a rich carbon and nitrogen source that is primarily transformed by bacterial communities. Bacteria capable of gradually hydrolyzing chitin into N-acetylglucosamine monomers can have applications in the transformation of residues from shrimp and other crustaceans. The objective of the present study was to isolate, characterize and identify microorganisms with high chitinolytic activity. These microorganisms were isolated and characterized based on macro- and microscopic morphological traits. Strains were selected on colloidal chitin agar medium primarily based on a hydrolysis halo larger than 2 mm and a growing phase no longer than 6 days. Secondary selection consisted of semi-quantitative evaluation of chitinolytic activity with a drop dilution assay. From the above, ten strains were selected. Then, strain-specific activity was evaluated. The B4 strain showed the highest specific activity, which was 6,677.07 U/mg protein. Molecular identification indicated that the isolated strains belong to the species Stenotrophomonas maltophilia.

Association Between SSR Molecular Markers and Chemical and Sensory Traits of Cacao Samples Using Multiple Regression Analysis.

The sensory properties of cacao beans are linked to the chemical composition of the seeds, and both characteristics are the partial results of its allelic composition. Therefore, it is useful to search for molecular markers associated with these traits. We perform multiple regression analysis to associate previously generated data of alleles generated with 12 SSR (of cultivated cacao trees) with data obtained from chemical and sensory characterization (of beans) of plants grown in the southern region from Mexico. When the association was significant, the mathematical models for predictive purposes were proposed. All phenotypic traits evaluated showed equations with setting values R2 > 0.5. All chemical characters tested have a significant association with at least two alleles (P < 0.05). In addition, the fat content was associated with six molecular markers (mTcCIR03209, mTcCIR12188, mTcCIR19286, mTcCIR07150, mTcCIR19310). The most common allele was mTcCIR12188, which was associated with the contents of eicosanoic acid, moisture, fat and total polyphenols content. The mTcCIR28362 allele is associated with sensory characters bitterness, musty odor, and roasted odor. These alleles could be useful as molecular markers of chemical and sensory characteristics of cacao samples.

Stingless bee honeys from Soconusco, Chiapas: a complementary approach / Mieles de abejas sin aguijón del Soconusco, Chiapas: enfoque complementario

Abstract Stingless bees are located in the tropic areas, and produced a sweet natural substance called pot honey, with different properties and uses. Recently, most studies are focused on characterizing them, in order to contribute to their knowledge and the establishment of quality laws. Thus physicochemical, acceptance and palynological studies were performed in stingless bee honeys from Soconusco, Chiapas, in order to learn and contribute to their knowledge in the Tropics. Nine honey samples were collected from Melipona solani (Ms), M. beecheii (Mb) and Scaptotrigona mexicana (Sm) in different meliponaries. Our results registered physicochemical values that ranged as follow; pH 2.8-4.8, electrical conductivity (EC) 114-1211 μS/cm, free acidity 24-100 meq/kg, aw 59-71 g/100g, moisture 35-38 %, color 0.13-0.75 Pfund scale, reducing sugars 47-71 %, hidroxymethylfurfural (HMF) not determined - 2.72 mg/100g, and diastase activity 1.92-11.22 DN. On the other hand, the principal component analysis (PCA) of physicochemical values showed that 86.9 % of the total variability between species was explained by the following parameters aw, moisture, free acidity, color, pH, sugars and EC. Sm honeys were associated (PCA) with a higher water content, free acidity and darker colors, while Melipona honeys with a sweeter taste and a lower diastase activity; thus honeys could be grouped by genera. The acceptance test showed that 78 % of honeys were preferred, being the SmCa sample in the category "I likely dislike" due to the bitter taste (disapproved by consumers). The melisopalynological results showed that M. beecheii honeys are monofloral with a 45 % of Fabaceae pollen, while Melipona solani and Scaptotrigona mexicana honeys are multi or polyfloral with diferent pollen types; Fabaceae, Melastomataceae, Malvaceae and Asteraceae. From this complementary study we can asume that it is necessary to implicate researchers with producers, so they could have accesss to stingless bee honey analysis and to help them to improve meliponaries management by identifying and introducing stingless bee flora.(AU)

Resumen En las regiones tropicales se ubican las abejas sin aguijón, las cuales producen una sustancia dulce denominada miel de cántaro con propiedades y usos diferentes a los de las abejas melíferas (Apis mellifera). Actualmente, se han desarrollado diversos trabajos enfocados a su caracterización, con la finalidad de contribuir con su conocimiento y el establecimiento de estándares de calidad. En este estudio se realizaron estudios fisicoquímicos, de aceptación y palinológicos en mieles de abejas sin aguijón de Soconusco, Chiapas. Se recolectaron nueve muestras de miel de las siguientes especies: Melipona solani (Ms), M. beecheii (Mb) y Scaptotrigona mexicana (Sm) en diferentes meliponarios. Nuestros resultados registraron valores fisicoquímicos que variaron de la siguiente manera: pH 2.8-4.8, conductividad eléctrica (CE) 114-1 211 μS/cm, acidez libre 24-100 meq/kg, aw 59-71 g/100 g, humedad 35-38 %, color 0.13-0.75 escala Pfund, azúcares reductores 47-71 %, hidroximetilfurfural (HMF) no determinado - 2.72 mg/100 g, y actividad de la días-tasa 1.92-11.22 ND. Por otro lado, el análisis del componente principal (PCA) de los valores fisicoquímicos mostró que el 86.9 % de la variabilidad total entre las especies se explica por los siguientes parámetros: aw, humedad, acidez libre, color, pH, azúcares y CE. Las mieles de Sm (PCA) se asociaron con un mayor contenido de agua, acidez libre y colores más oscuros, mientras que las mieles de Melipona con un sabor más dulce y una actividad de días-tasa más baja; por lo tanto, las mieles podrían agruparse por géneros. La prueba de aceptación mostró que el 78 % de las mieles eran preferidas, siendo la muestra de SmCa en la categoría "Probablemente no me gusta" debido al sabor amargo (desaprobado por los consumidores). Los resultados melisopalinológicos mostraron que las mieles de M. beecheii son monoflorales con un 45 % de polen de Fabaceae, mientras que las mieles de M. solani y S. mexicana son multi o poliflorales con diferentes tipos de polen: Fabaceae, Melastomataceae, Malvaceae y Asteraceae. De este estudio complementario observamos que se requiere poner en contacto a investigadores y productores, para que el acceso a los análisis de las mieles de abejas sin aguijón sea posible, y así mismo se pueda ayudar con el mejoramiento del manejo de los melionarios al momento de identificar e introducir la flora preferida por las abejas sin aguijón.(AU)

Characterization of Aloe vera-chitosan composite films and their use for reducing the disease caused by fungi in papaya Maradol.

Composite films with Aloe vera (A), chitosan (Ch) and essential oils (EOs) were formulated. Six of the twelve combinations tested formed films: A70Ch30, A70Ch30-15, A60Ch40, A60Ch40-15, A50Ch50, and A50Ch50-15. The A60Ch40-15 film showed the best physicochemical characteristics as well as the greatest in vitro antifungal activity. Although the A90Ch10 and A80Ch20-15 mixtures did not form films, their solutions showed high antifungal activity in vitro. Based on multivariate analysis of the data, A60Ch40-15, A90Ch10 and A80Ch20-15 films were selected as coating treatments for papaya during storage at 30 ± 2 °C and 80% RH. Uncoated fruits (control 1) and treated with synthetic fungicide (control 2) were used as control. Coated fruits showed lower respiration rate, greater firmness and fewer changes in external coloration compared to control. Furthermore, these coatings reduced the incidence and severity of fungal disease by 40-50% compared to control 2. Aloe vera-chitosan films (A90Ch10 and A60Ch40-15), enriched with the EOs of cinnamon (10 mL L-1) and thyme (10 mL L-1), improved quality of the fruit (higher firmness, lower CO2 content, less internal color change) with 50% less disease incidence during storage at room temperature.

Alcaloides y polifenoles del cacao, mecanismos que regulan su biosíntesis y sus implicaciones en el sabor y aroma / Cacao alkaloids and polyphenols: Mechanisms that regulate their biosynthesis and its implications on the taste and aroma

El sabor y aroma de los granos de cacao (Theobroma cacao L.) fueron las principales razones que promovieron su domesticación y uso alimentario por los pueblos precolombinos de Mesoamérica. Incluso hoy día, la calidad sensorial determina la clasificación entre cacaos finos y a granel. Muchos compuestos químicos de las almendras son responsables de la calidad sensorial, pero sobresalen los polifenoles y los alcaloides, compuestos que de manera directa inciden en el sabor y palatabilidad de las almendras y de manera indirecta sobre los precursores de aroma. Los alcaloides están asociados con el amargor. Su concentración está relacionada con la variedad y se modifica con el procesamiento. Los polifenoles son responsables, junto con otras moléculas de la astringencia (poco deseable en chocolates), pero también de propiedades antioxidantes deseables por los consumidores. En esta revisión se abordan aspectos de la biosíntesis de estas importantes moléculas en las almendras de cacao, de las implicaciones en el sabor y aroma, así como los cambios que ocurren durante el procesamiento de las mismas(AU)

The flavor and aroma of cacao (Theobroma cacao) beans were the main reasons that promoted its domestication and food-use by pre-Columbian peoples of Mesoamerica. Polyphenols and alkaloids are compounds that directly affect the flavor of the cocoa beans and indirectly on the flavor precursors. The alkaloids are associated with bitterness; its concentration is related to the cultivar and its modifying through the processing. Polyphenols molecules are responsible together with other molecules of the astringency (not desirable in chocolate), but also are responsible for antioxidant properties, very desirable by consumers. This review focuses on aspects of the biosynthesis of these important molecules in cocoa beans as well as implications in taste and flavor. The changes of these molecules that occur during processing are also approached(AU)

Sex expression and floral diversity in Jatropha curcas: a population study in its center of origin.

Sex expression and floral morphology studies are central to understand breeding behavior and to define the productive potential of plant genotypes. In particular, the new bioenergy crop Jatropha curcas L. has been classified as a monoecious species. Nonetheless, there is no information about its reproductive diversity in the Mesoamerican region, which is considered its center of origin and diversification. Thus, we determined sex expression and floral morphology in J. curcas populations from southern Mexico and Guatemala. Our results showed that most of J. curcas specimens had typical inflorescences with separate sexes (monoecious); meanwhile, the rest were atypical (gynoecious, androecious, andromonoecious, androgynomonoecious). The most important variables to group these populations, based on a discriminant analysis, were: male flower diameter, female petal length and male nectary length. From southern Mexico "Guerrero" was the most diverse population, and "Centro" had the highest variability among the populations from Chiapas. A cluster analysis showed that the accessions from southern Mexico were grouped without showing any correlation with the geographical origin, while those accessions with atypical sexuality were grouped together. To answer the question of how informative are floral morphological traits compared to molecular markers, we perform a Mantel correlation test between the distance matrix generated in this study and the genetic distance matrix (AFLP) previously reported for the same accessions. We found significant correlation between data at the level of accessions. Our results contribute to design genetic improvement programs by using sexually and morphologically contrasting plants from the center of origin.

Unique haplotypes of cacao trees as revealed by trnH-psbA chloroplast DNA.

Cacao trees have been cultivated in Mesoamerica for at least 4,000 years. In this study, we analyzed sequence variation in the chloroplast DNA trnH-psbA intergenic spacer from 28 cacao trees from different farms in the Soconusco region in southern Mexico. Genetic relationships were established by two analysis approaches based on geographic origin (five populations) and genetic origin (based on a previous study). We identified six polymorphic sites, including five insertion/deletion (indels) types and one transversion. The overall nucleotide diversity was low for both approaches (geographic = 0.0032 and genetic = 0.0038). Conversely, we obtained moderate to high haplotype diversity (0.66 and 0.80) with 10 and 12 haplotypes, respectively. The common haplotype (H1) for both networks included cacao trees from all geographic locations (geographic approach) and four genetic groups (genetic approach). This common haplotype (ancient) derived a set of intermediate haplotypes and singletons interconnected by one or two mutational steps, which suggested directional selection and event purification from the expansion of narrow populations. Cacao trees from Soconusco region were grouped into one cluster without any evidence of subclustering based on AMOVA (F ST = 0) and SAMOVA (F ST = 0.04393) results. One population (Mazatán) showed a high haplotype frequency; thus, this population could be considered an important reservoir of genetic material. The indels located in the trnH-psbA intergenic spacer of cacao trees could be useful as markers for the development of DNA barcoding.

Reproductive biology of the biofuel plant Jatropha curcas in its center of origin.

In this work, we studied the main characteristics of flowering, reproductive system and diversity of pollinators for the biofuel plant Jatropha curcas (L.) in a site of tropical southeastern Mexico, within its center of origin. The plants were monoecious with inflorescences of unisexual flowers. The male flowers produced from 3062-5016 pollen grains (266-647 per anther). The plants produced fruits with both geitonogamy and xenogamy, although insect pollination significantly increased the number and quality of fruits. A high diversity of flower visiting insects (36 species) was found, of which nine were classified as efficient pollinators. The native stingless bees Scaptotrigona mexicana (Guérin-Meneville) and Trigona (Tetragonisca) angustula (Latreille) were the most frequent visitors and their presence coincided with the hours when the stigma was receptive. It is noteworthy that the female flowers open before the male flowers, favoring xenogamy, which may explain the high genetic variability reported in J. curcas for this region of the world.

Cacao alkaloids and polyphenols: Mechanisms that regulate their biosynthesis and its im- plications on the taste and aroma.

The flavor and aroma of cacao (Theobroma cacao) beans were the main reasons that promoted its domestication and food-use by pre-Columbian peoples of Mesoamerica. Polyphenols and alkaloids are compounds that directly affect the flavor of the cocoa beans and indirectly on the flavor precursors. The alkaloids are associated with bitterness; its concentration is related to the cultivar and its modifying through the processing. Polyphenols molecules are responsible together with other molecules of the astringency (not desirable in chocolate), but also are responsible for antioxidant properties, very desirable by consumers. This review focuses on aspects of the biosynthesis of these important molecules in cocoa beans as well as implications in taste and flavor. The changes of these molecules that occur during processing are also approached.