Examinando por Autor "Vera Pacheco, Katerine"

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  • Publicación
    Acceso abierto
    Functional metagenomic analysis of the coffee (coffea arabica) fermentation
    (2018) Vera Pacheco, Katerine; Valdivieso Quintero, Wilfredo; Mantilla Paredes, Andrea Juliana; Jaimes, William; Torrado, Jorge; Zafra, German
    This study focused on studying the influence of the temperature and time on the functional diversity of the microbial populations involved in coffee (Coffea arabica) fermentation, using a shotgun metagenomic approach. Fermentations of depulped coffee grains were carried out under controlled and non-controlled temperature conditions for 24 h. Paired-end whole genome sequencing from mucilage samples was performed using an Illumina Hiseq 2x150 platform. Global and specific gene abundance was analyzed using the KEGG orthology (KO). Results showed a predominance of genes involved in carbohydrate and aminoacid metabolism during fermentations. The abundance of genes involved in glycolysis / gluconeogenesis, lactate fermentation and mixed acids were higher during fermentation conducted under non-controlled temperature conditions; however, fermentations carried out at 11 °C induced a significant increase in the abundance of genes involved in the synthesis of aminoacid, lipids and organic acids, as well as protein secretion systems. We concluded that different temperatures and conditions in fermentations produce appreciable changes on the functional potential of both aminoacid and carbohydrate metabolism, especially in the abundance of Nacetyl-lysine deacetylase, pyruvate dehydrogenase and 6-phosphofructokinase genes, which in turn could greatly affect the taste and quality of coffee. This information, together with the results from coffee cupping, provided valuable insights into the role microorganisms involved in coffee fermentation play in obtaining better taste attributes, as well to identify key genes and potential metabolic pathways associated with these special attributes.
  • Publicación
    Acceso abierto
    Molecular detection and characterization of novel lipase genes of the lipolytic yeast Candida palmioleophila
    (2018-05-01) Rodríguez Mateus, Zully; Vera Pacheco, Katerine; Zafra, German
    In this study we analyzed the genetic variability of lipase gene sequences from eight oil and grease-degrading strains of Candida palmioleophila and to relate it to their degrading ability. The genetic variability of lipase genes was analyzed by PCR-restriction fragment length polymorphism (PCR-RFLP) and low-stringency single specific primer- PCR (LSSP-PCR), in order to obtain specific DNA fingerprints from each strain, which were subsequently compared by bioinformatic programs. DNA fingerprints were contrasted to the ability of each strain to remove palm oil in liquid culture. The results showed that at least three genes encoding lipases are present in C. palmioleophila, two of them resembling the LIP2 and LIP6 genes of C. albicans. DNA fingerprints obtained by LSSP-PCR revealed differences in the sequences of C. palmioleophila lipase genes, which allowed to group the strains according to their degrading activity. C. palmioleophila strains SACL05, SACL08 and SACL11, which showed the highest removal of palm oil after 72 h (77 to 79 % removal), were grouped in a single clade in dendrograms. Similarly, strains SACL01, SACL03, SACL06 and SACL09, which showed intermediate removal activity of palm oil (54 to 76%) grouped in a different clade. This suggests the genetic variability in lipase genes is directly related to the differences found in the efficiency of degradation of oils. On the other hand, DNA fingerprints obtained by PCR-RFLP did not allow to differentiate the strains and did not generate changes in the bands patterns between the analyzed strains. In conclusion, this study reported for the first time the detection and characterization of lipase genes from the lipolytic yeast Candida palmioleophila, and their association to the degradation of oils.