Examinando por Autor "Pacheco, Nicolás"

Mostrando 1 - 3 de 3
  • No hay miniatura disponible
    Ítem
    Adaptive signatures of emerging Salmonella serotypes in response to stressful conditions in the poultry industry
    (LWT, Volume 2151 January 2025 Article number 117188, 2025) Krüger, Gabriel I.; Pardo-Esté, Coral; Álvarez, Javiera; Pacheco, Nicolás; Castro-Severyn, Juan; Alvarez-Thon, Luis; Saavedra, Claudia P.
    Salmonella, a zoonotic pathogen, is commonly transmitted through contaminated animal products. This bacterium is emerging in poultry production, often exhibiting multidrug resistance (MDR) and high virulence. Understanding the adaptive mechanisms that allow Salmonella to survive in hostile environments and become virulent is crucial for preventing outbreaks that threaten both the industry and public health. This study uses machine learning to identify adaptive genomic signatures in Salmonella isolates from the poultry industry, focusing on responses to environmental stressors. Significant genomic modifications were found in functions like membrane and cell wall biogenesis, amino acid metabolism, and inorganic ion metabolism, including genes related to antibiotic resistance and virulence. The machine learning model demonstrated high precision (0.980) and accuracy (0.954) in classifying isolates based on their genomic characteristics, with an Area Under the Receiver Operating Characteristic Curve (AUROC) of 0.98. The model identified Salmonella Infantis as one of the most stress-resistant serovars in the poultry industry. The identification of critical genomic sequences underscores the importance of these traits in understanding the bacterium's adaptive mechanisms. These findings underscore the importance of genomic surveillance and advanced bioinformatics to manage emerging pathogens like Salmonella Infantis. © 2024 The Authors
  • Miniatura
    Ítem
    Characterization of biofilm formation by Exiguobacterium strains in response to arsenic exposure
    (PubMed, 2023-12-12) Pavez, Valentina B.; Pacheco, Nicolás; Castro-Severyn, Juan; Pardo-Esté, Coral; Álvarez, Javiera; Zepeda, Phillippi; Krüger, Gabriel; Gallardo, Karem; Melo, Francisco; Vernal, Rolando; Aranda, Carlos; Remonsellez, Francisco; Saavedra, Claudia P.
    In this work, we characterized the composition, structure, and functional potential for biofilm formation of Exiguobacterium strains isolated from the Salar de Huasco in Chile in the presence of arsenic, an abundant metalloid in the Salar that exists in different oxidation states. Our results showed that the Exiguobacterium strains tested exhibit a significant capacity to form biofilms when exposed to arsenic, which would contribute to their resistance to the metalloid. The results highlight the importance of biofilm formation and the presence of specific resistance mechanisms in the ability of microorganisms to survive and thrive under adverse conditions.
  • Miniatura
    Ítem
    Engineering the Osmotic State of Pseudomonas putida KT2440 for Efficient Cell Disruption and Downstream Processing of Poly(3-Hydroxyalkanoates)
    (Frontiers Media S.A., 2020-03) Poblete-Castro, Ignacio; Aravena-Carrasco, Carla; Orellana-Saez, Matias; Pacheco, Nicolás; Cabrera, Alex
    In the last decade, the development of novel programmable cell lytic systems based on different inducible genetic constructs like the holin–endolysin and lysozyme appears as a promising alternative to circumvent the use of costly enzymes and mechanical disrupters for downstream processing of intracellular microbial products. Despite the advances, upon activation of these systems the cellular disruption of the biocatalyst occurs in an extended period, thus delaying the recovery of poly(3-hydroxyalkanoate) (PHA). Herein the osmotic state of Pseudomonas putida KT2440 was engineered by inactivating the inner-membrane residing rescue valve MscL, which is responsible mainly for circumventing low-osmolarity challenges. Then the major outer membrane porin OprF and the specific porin OprE were overproduced during PHA producing conditions on decanoate-grown cells. The engineered P. putida strains carrying each porin showed no impairment on growth rate and final biomass and PHA yield after 48 h cultivation. Expression of both porins in tandem in the mutant strain KTΔmscL-oprFE led to a slight reduction of the biomass synthesis (∼10%) but higher PHA accumulation (%wt) relative to the cell dry mass. Each strain was then challenged to an osmotic upshift for 1 h and subsequently to a rapid passage to a hypotonic condition where the membrane stability of the KTΔmscL-oprFE suffered damage, resulting in a rapid reduction of cell viability. Cell disruption accounted for >95% of the cell population within 3 h as reported by colony forming units (CFU), FACS analyses, and transmission electron microscopy. PHA recovery yielded 94.2% of the biosynthesized biopolymer displaying no significant alterations on the final monomer composition. This study can serve as an efficient genetic platform for the recovery of any microbial intracellular compound allowing less unit operation steps for cellular disruption. © Copyright © 2020 Poblete-Castro, Aravena-Carrasco, Orellana-Saez, Pacheco, Cabrera and Borrero-de Acuña.