Caracterización de comunidades microbianas asociadas a cerezas frescas y secas de café de la región de Tabasco mediante métodos dependientes e independientes del cultivo
In coffee processing, a large number of microorganisms that can have an effect on the quality of the product are naturally present. Studies focused on shaping microbial communities, however, are scarce, and only a few use cultureindependent methods. In this study, the isolation and molecular identif...
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| Tipo de recurso: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2019 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:ff365529b |
| Acceso en línea: | https://doi.org/10.24275/uami.ff365529b |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Biotecnología info:eu-repo/classification/LEM/Coffee -- Processing info:eu-repo/classification/LEM/Café -- Cultivo info:eu-repo/classification/LEM/Biotechnology info:eu-repo/classification/LEM/Coffee -- Production info:eu-repo/classification/LEM/Café -- Procesamiento info:eu-repo/classification/LEM/Coffee -- Culture info:eu-repo/classification/LEM/Café -- Producción -- Tabasco (México : Estado) info:eu-repo/classification/cti/6 |
| Sumario: | In coffee processing, a large number of microorganisms that can have an effect on the quality of the product are naturally present. Studies focused on shaping microbial communities, however, are scarce, and only a few use cultureindependent methods. In this study, the isolation and molecular identification (16S rRNA and ITS region sequence analysis) of bacteria and filamentous fungi, from fresh and dried coffee cherries from Tabasco (Tacotalpa), was carried out; potential ochratoxin A (OTA) producers’ occurrence was evaluated, and the toxin production was determined by HPLC. Complementary to this, the metabarcoding technique (16S rDNA V3–V4 region and ITS2 region sequencing on an Illumina MiSeq™ platform) was employed as a culture-independent method to analyze the cherries bacterial and fungal communities. With the bacteria isolation, the abundance of Gram-negative bacteria was observed, among which, the genus Klebsiella and the species Pantoea agglomerans were identified. Among the isolated fungi, the presence of different genera and species, that in some cases were not detected by metabarcoding, was determined and in particular, it was observed, only in dried cherries, the contamination with Aspergillus niger, for which the OTA production (105.03 ± 16.36 μg / kg of medium) was demonstrated by HPLC. On the other hand, with metabarcoding, some coincidences were observed such as the presence of Klebsiella and P. agglomerans, among the bacteria represented with greater abundance, and the contamination with A. niger in dried cherries. This technique, however, allowed a deeper analysis of the microbial diversity and to evidence the difference in fresh and dried cherries populations. Among the bacterial operational taxonomic units (OTUs), Proteobacteria and Firmicutes were the dominant phyla, with the Firmicutes in a higher proportion in dried cherries than in fresh ones due to the presence of the genus Weissella. Among the fungal OTUs, Ascomycota and Basidiomycota were the dominant phyla, with a higher proportion of Basidiomycota in fresh cherries than in dried cherries, in which a higher proportion of the genus Aspergillus was also observed. Additionally, yeasts abundance was determined at the two processing points, and many genera and species of bacteria and filamentous fungi that were not found by isolation were detected, demonstrating once again the importance of using culture-dependent and culture-independent methods in conjunction to perform a better characterization of the microbial communities present in coffee cherries and their processing. |
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