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

Effect of fermentation and roasting on the content of biogenic amines in cacao beans

Abstract: Introduction. Biogenic amines (BA) can be found in foods subject to fermentation, in considerable quantities can cause poisoning to the consumer. Objective. The aim of this study was to evaluated the effect of fermentation and the roasting on the production-degradation of BA of cocoa seeds. Methods. In a first phase (P1), under a completely randomized design, the role of fermentation on BA was verified by four treatments, inhibition of yeast growth; inhibition of bacterial growth; traditional fermentation and unfermented seeds. In a second phase (P2), through a repeated measure factorial design 3X2, six treatments were evaluated, product of the combination of two lactic acid bacteria (LAB) (L. plantarum, L. fermentum, L. plantarum + L. fermentum) and two concentrations of starter culture (106 CFU/g, 108 CFU/g) to investigate the effect of exogenous LAB in the production-suppression of BA. Results. In the P1, the presence of three AB of interest was confirmed, with putrescine being found in greater quantity (37 - 45.2 ìg/g). Histamine and tyramine were found in lower concentrations without effect of fermentation on AB production. The E2 showed an effect of the LAB in the production of putrescine, reaching values up to 41.1 ìg/g when the highest LAB concentration was inoculated during the fermentation. Histamine was reduced in the beans after roasting when L. plantarum was inoculated to 108 CFU/g. Conclusion. The exogenous LAB do not have a essential role in the production-degradation of AB during the fermentation of cocoa seeds

A General Overview of Sweet Sorghum Genomics

Sorghum is one of the main cereal crops, its consumption is large, since it provides grain, fiber and biofuel. Likewise, its genome, with only 10 diploid chromosomes, makes it an attractive model for research and genetic improvement. Sorghum is the most studied C4 plant of its genus; several lines have been developed under three main characteristics: grain, forage and sugar biomass. Compared to other crops, sweet sorghum possesses high levels of highly fermentable sugars in the stem. Also, it has the ability of producing high production yields in marginal lands. These characteristics make it and attractive crop for the generation of biofuels. Molecular markers associated to several resistances and tolerances to biotic and abiotic factors have been described in literature. These allow the development of high-density linkage maps, which, along with the rising availability of sorghum genomes, will accelerate the identification of markers and the integration of the complete genome sequence. This will facilitate the selection of traits related to biofuels and the marker-assisted genetic improvement. Most of the information presented in this review is focused in Sorghum bicolor (L.) Moench. However, from the bioenergetics perspective, it is limited to sweet sorghum, which represents a promising opportunity for further studies

Diversidad morfológica del fruto en germoplasma nativo de mango Mangifera indica L. (Anacardiaccac) nativo de Chiapas, México

Instituto Politécnico Nacional (proyecto CGPI-20050084) y Fondo Mixto-Gobierno del Estado de Tamaulipa

Uso combinado de radiación UV-C y biorecubrimiento de quitosán con aceites esenciales para el control de hongos en papaya Maradol

Resumen La antracnosis y pudrición blanda en frutos de papaya provocan deterioro de la calidad, así como grandes pérdidas durante el manejo postcosecha. El uso de estrategias individuales para el control de enfermedades resulta poco eficiente. Por lo anterior, en el presente estudio se evaluó el efecto sinérgico de varias estrategias de control sobre la incidencia de enfermedad causada por la inoculación de esporas de los hongos Colletotrichum gloeosporioides (Penz.) y Rhizopus stolonifer (Ehrenb.) en papaya var. Maradol. Se evaluaron tratamientos resultantes de la combinación del uso de biorecubrimientos compuestos elaborados con quitosán (15 g L-1) adicionadas con aceites esenciales (AE) de clavo, tomillo y/o lima (5 ó 10 mL L-1 de cada AE) y tres dosis de irradiación UV-C (0.97 kJ·m-2, 2 kJ·m-2 y 2.88 kJ·m-2), aplicados a las 12, 24 y 48 h post-inoculación de esporas de los fitopatógenos. El tratamiento donde se combinó el biorecubrimiento adicionado con 10 mL L-1 de AE de clavo y 10 mL L-1 de AE de tomillo y una dosis de irradiación UV-C de 2.88 kJ m-2 (B1T92) aplicado a las 24 h post-inoculación de esporas, logró mantener la incidencia de enfermedad (para ambos hongos evaluados) a valores menores de 25% durante nueve días de almacenamiento a temperatura de 28 ± 3 °C y 80% de HR. Este mismo tratamiento redujo la velocidad específica de la enfermedad, con valores de 0.549 y 0.029 d-1 para C. gloeosporioidesy R. stolonifer, respectivamente. Otros tratamientos (B2T62, B1T34, B1T34, B1T94) presentaron actividad antifúngica (valores promedio de incidencia de 35% durante todo el almacenamiento) para R. stolonifer. Los resultados de este trabajo demuestran que el efecto sinérgico del uso de biorecubrimientos de quitosán con aceites esenciales y energía UV-C controla el desarrollo de hongos causantes de antracnosis y pudrición blanda en frutos de papaya Maradol

Bacterias ácido lácticas nativas como cultivo iniciador para la elaboración de queso crema mexicano

Introduction. The bacterial starter cultures are successfully used in the production of artisan cheeses, since they help to maintain sui generis sensory characteristics, as well as controlling the presence of pathogens. It has been reported that natives strains are the best options to perform this function. Objective. The aim of this research was to evaluate the effect of the addition of lactic acid bacteria (LAB) isolated from the traditional process of cheese making, as a starters in the manufacture of cream cheese from pasteurized milk. Materials and methods. The research was done in the Ocosingo city, Chiapas, Mexico, during the months of February to November from 2016. 37 strains with different morphology were isolated, from milk, cheese and whey, of which 21 were Gram positive, catalase and peroxidase negative. For their acidifying capacity, eight strains were selected, with which six treatments were formulated (combinations of three strains). Results. The treatment that was most accepted by consumers was restructured into three new treatments (three combinations of two strains). Of these new treatments, that one (T8) where two LABs (2S and 30Q) were combined was similar in color, firmness and fat content to the control (cream cheese made with unpasteurized milk). Although they were slightly different in protein, moisture and ash content, however, expert panelists found no significant differences (proof of discrimination A not A) between the T8 cream cheese and the control. This same treatment promoted microbiological counts (aerobic mesophilic, total coliforms, and molds and yeasts) lower than those established by the sanitary standards. Conclusion. The use of BAL 2S and 30Q as starter culture allowed a cream cheese to be obtained from pasteurized milk with similar characteristics to traditional cream cheese, besides microbiologically safe.Introducción. Los cultivos bacterianos iniciadores son empleados exitosamente en la elaboración de quesos artesanales, ayudan a mantener las características sensoriales sui generis, además, controlan la presencia de patógenos. Se ha reportado que las cepas nativas son las mejores opciones para realizar esta función. Objetivo. El objetivo de la presente investigación fue evaluar el efecto de la adición de bacterias ácido lácticas (BAL), aisladas del proceso artesanal de elaboración de queso como iniciadoras en la elaboración de queso crema a partir de leche pasteurizada. Materiales y métodos. El trabajo se realizó en la región de Ocosingo, Chiapas, México, durante los meses de febrero a noviembre del año 2016. Se aislaron 37 cepas de diferente morfología, provenientes de leche, queso y suero, de las cuales 21 fueron Gram positivas, catalasa y peroxidasa negativas. Por su capacidad acidificante, se seleccionaron ocho cepas con las cuales se formularon seis tratamientos (combinaciones de tres cepas). Resultados. El tratamiento que sensorialmente fue más aceptado por los consumidores, se reestructuró en tres nuevos tratamientos (tres combinaciones de dos cepas). De estos nuevos tratamientos, aquel (T8) donde se combinaron dos BAL (2S y 30Q) fue similar en color, firmeza y contenido de grasa al testigo (queso crema elaborado con leche sin pasteurizar). Fueron ligeramente diferentes en el contenido de proteína, humedad y cenizas, sin embargo, los panelistas expertos no encontraron diferencias (prueba de discriminación A no A) significativas entre el queso crema T8 y el testigo. Este mismo tratamiento promovió en el queso crema recuentos microbiológicos (mesófilos aerobios, coliformes totales, mohos y levaduras) inferiores a las establecidas por las normas sanitarias. Conclusión. El uso de las BAL 2S y 30Q como cultivo iniciador permitió obtener un queso crema a partir de leche pasteurizada con características similares al queso crema tradicional, pero que resultó microbiológicamente inocuo

Films of Chitosan and Aloe vera for Maintaining the Viability and Antifungal Activity of Lactobacillus paracasei TEP6

The present study aimed to evaluate the effect of Aloe vera addition on the viability and antifungal activity of TEP6 (Lactobacillus paracasei) bacteria immobilized on chitosan films for 28 days. Different chitosan and A. vera proportions and carbon sources at several pH values were tested as formulations for supporting the microorganism. Bacterial viability was maintained in freshly made films, with values of 10.4, 10.8 and 10.9 log CFU·g−1 for the formulations containing 70% (T11), 100% (T8) and 100% (T16) of A. vera, respectively. The same formulations (T8, T11 and T16) maintained bacterial viability for 14 days of film storage with a loss to values of 9.5 log CFU·g−1. By applying a quarter fraction 25–2 experimental design with an array of five factors, the factors with the greatest influence on viability and antifungal activity were determined. The optimal conditions for viability were the formulation with 100% A. vera, pH 4.5 and 0.1 M glucose. The antifungal activity of fresh films was influenced by the formulation with 10 g·L−1 glycerol and 100% A. vera, showing a 60% inhibition of fungal (Colletotrichum gloeosporioides) growth. The films developed in this study may have the potential to be used as coatings on vegetal products susceptible to attack by Colletotrichum gloesporioides

Capacidad antifúngica de biopelículas de quitosán conteniendo bacterias ácido lácticas

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.  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.