Bioprospecting of indigenous yeasts involved in cocoa fermentation using sensory and chemical strategies for selecting a starter inoculum.

Cocoa fermentation is the key and most relevant process in the synthesis of aroma and flavor precursor molecules in dry beans or raw material for producing chocolate. Because this process occurs in an uncontrolled manner, the chemical and sensory quality of beans can vary and be negatively affected. One of the strategies for the standardization and improvement of the sensory quality of chocolate is the introduction of microbial starter cultures. Among these, yeasts involved in fermentation have been studied because of their pectinolytic and metabolic potential in the production of volatile compounds. This study was aimed at isolating and characterizing, both sensory and chemically, yeasts involved in cocoa fermentation that could be used as starter cultures from two agro-ecological regions for the cultivation of cocoa in Colombia. The microbiological analyses identified 22 species represented mostly by Saccharomyces cerevisiae, Wickerhamomyces anomalus and Pichia sp. The preliminary sensory analysis of eight of these species showed that Hanseniaspora thailandica and Pichia kluyveri presented sensory profiles characterized by high intensity levels of fruity notes, which could be ascribed to the production of ethyl acetate, isoamyl acetate, and 2-phenylethyl acetate.

Assessment of the fungal community associated with cocoa bean fermentation from two regions in Colombia.

The quality of the cocoa seeds depends on various factors. Fermentation is among them because during this process flavor precursors are synthesized through the action of fungi and bacteria, whose diversity can change depending on the geographic location and the agricultural practices. This research aimed to characterize and compare the fungal community involved in spontaneous fermentations carried out under the same post-harvest agricultural practices in two farms located at completely different agro­ecological zones by application of a high-throughput amplicon sequencing method. The results showed that the diversity of biological variants is different between regions. In the Magdalena Medio region, the fermentations were dominated by Hanseniaspora opuntiae, and Saccharomyces sp., while in Urabá region all the fermentation was characterized by an almost constant diversity and high abundance of H. opuntiae. In each site, unique biological variants of these two genera were detected. Additionally, differences were observed in the physicochemical parameters such as the pH and temperature of the fermentation mass, and the duration of the process. The analyses of these results allow concluding that the environmental conditions and indigenous microbiota of each cocoa-cultivation zone explained the differences found in this study.

Microbiota bacteriana asociada al papel moneda de circulación en Colombia / Bacterial microbiota on circulating Colombian banknotes

Diariamente los seres humanos están en interacción con objetos de uso continuo, como el papel moneda, sin el conocimiento de que estos almacenan microorganismos y de que nos exponemos al contacto con potenciales patógenos. La composición de la comunidad bacteriana en un billete colombiano fue determinada mediante el secuenciamiento profundo de librerías de amplicones 16S. Se encontraron 233 géneros bacterianos; 12 de estos géneros corresponden a especies con potencial patogénico. El género más abundante fue Propionibacterium, seguido de Streptococcus, Staphylococcus Pseudomonas . Este es el primer reporte de la diversidad bacteriana que puede ser alojada en este objeto de alta circulación en Colombia. Pocos estudios en el mundo han mostrado este nivel de detalle de la microbiota en billetes de circulación y ofrece un panorama mucho más amplio de la exposición diaria a microorganismos al utilizar papel moneda en las condiciones en las que se utiliza en Colombia.

Commonly used objects such as currency paper can be colonised by bacteria and can serve as carriers of microbes. This colonisation might expose us to unnoticed pathogenic bacteria. In this study, the researchers obtained a detailed panorama of the microbes that can be carried on currency notes in Colombia by using 454 next-generation deep sequencing of 16S amplicón libraries. A total of 233 bacterial genera were detected and classified, 12 of which are potential human pathogens. The most abundant genera were Propionibacterium, Streptococcus, Staphylococcus and Pseudomonas. To date, this is the first in-depth analysis of the microbiota carried by circulating banknotes in our continent and it offers insights into daily exposure to microbes when using banknotes in Colombia.

RICHNESS, CELLULOLYTIC ACTIVITY, AND FUNGICIDE SUSCEPTIBILITY OF FUNGI FROM A BIRD BIOLOGICAL COLLECTION / Riqueza, actividad celulolítica y susceptibilidad a fungicidas de hongos de una colección biológica de aves

Biological collections in natural history museums serve important purposes to the scientific community and the general public, however, their value and utility might be diminished by biodeterioration. We studied a biological collection that represents more than sixty years of avifauna sampling of Colombia, the country with the highest bird diversity. An initial inspection of the collection showed that the general appearance of some specimens was compromised by mold-like growth on their surfaces. We aimed at (i) identifying the taxonomic affiliation of these fungi, (ii) evaluating their cellulolytic activity, and (iii) probing chemical agents that could be utilized to control their growth. The most common fungi genera were Aspergillus, Penicillium, Chaetomium, and Trichophyton, most of which can degrade cellulose. Zinc chloride and salicylic acid showed to be effective fungicides. Based on this, we propose some actions to control the fungi-pest in this biological collection of birds.

Las colecciones biológicas en los museos de historia natural juegan un papel importante tanto para la comunidad cientifica como para el público en general. Sin embargo, su valor y utilidad pueden verse afectados por la biodeterioración de sus ejemplares. Se estudio una colección biológica de aves que representa más de sesenta anos de esfuerzo de muestreo de la avifauna del pais más rico en aves. Una inspección inicial mostró que la apariencia general de algunos de los especimenes de la colección se encontraba afectada por hongos. Los objetivos de este estudio fueron (i) identificar la afiliación taxonómica de los hongos, (ii) determinar la actividad celulolítica y (iii) probar agentes químicos que puedan ser utilizados para controlar su desarrollo. Los géneros de hongos más comunes fueron Aspergillus, Penicillium, Chaetomium y Trichophyton, de los cuales la mayoria presentan la capacidad de degradar celulosa. Adicionalmente, el cloruro de zinc y el ácido salicilico actuaron como fungicidas efectivos. De acuerdo con en estos resultados proponemos algunas acciones para controlar la contaminación por hongos en la colección de aves.

MICROBIOTA RIZOSFÉRICA DE Espeletia spp. DE LOS PÁRAMOS DE SANTA INÉS Y DE FRONTINO-URRAO EN ANTIOQUIA, COLOMBIA / Rizospheric Microbiota of Espeletia spp. from Santa Inés and Frontino-Urrao Paramos in Antioquia, Colombia

El frailejón cuyo nombre científico es Espeletia spp., es considerado el arbusto emblema de los páramos, un ecosistema de importancia debido a que son fuente de agua y de materia orgánica, donde se han registrado un alto número de especies biológicas endémicas. Considerando la relevancia de la microbiota en la estructuración del suelo y en la disponibilidad de los nutrientes como soporte para el crecimiento vegetal, se determinaron las poblaciones microbianas cultivables de importancia funcional como dinamizadora de nutrientes en el suelo rizosférico de Espeletia spp. en el páramo de Santa Inés y en el de Frontino-Urrao en Antioquia. Los suelos se caracterizaron por ser ácidos y en el páramo de Frontino-Urrao se reportaron los mayores contenidos de materia orgánica y nitrógeno. La abundancia de microorganismos fue similar en los dos páramos y se registró únicamente variación en la abundancia de bacterias formadoras de endospora, que superaron en Frontino-Urrao 3,8 veces el contenido respecto al de Santa Inés. En ambos páramos se reportaron bacterias y hongos solubilizadores de fosfato y degradadores de celulosa que pueden ser empleados en procesos de restauración de suelos paramunos degradados por la minería, la ganadería o la agricultura.

The frailejón (Espeletia spp.) is the emblematic shrub of the paramo. This is an important ecosystem because they are sources of water and organic matter, and are inhabited by a high number of endemic biological species. Considering the importance of the microbiota in soil structure and nutrients availability to support plant growth, we assessed the cultivable microbial populations in Espeletia spp. rhizosphere in Santa Inés and Frontino-Urrao paramos, including functional groups with important role in cycling nutrients. The soil pH was strongly acid in both sites and the organic matter and nitrogen contents were highest in Frontino-Urrao soil. Nevertheless, the microbial abundance was similar in these sites except the content of endospore-forming bacteria, which was 3.8 fold large in Frontino-Urrao. Phosphate solubilizing and cellulolytic microorganisms were found in both sites. Those microorganisms would be used for soil restoration processes in paramos degraded by mining, livestock or agriculture.