Investigación

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https://hdl.handle.net/10669/1419

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Examinando Investigación por Autor "Abarca Alvarado, Juan Gabriel"

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    Ítem
    Characterization of Batrachochytrium dendrobatidis Inhibiting Bacteria from Amphibian Populations in Costa Rica
    (2017) Madison, Joseph D.; Berg, Elizabeth A.; Abarca Alvarado, Juan Gabriel; Whitfield, Steven M.; Gorbatenko, Oxana; Pinto Tomás, Adrián A.; Kerby, Jacob L.
    Global amphibian declines and extinction events are occurring at an unprecedented rate. While several factors are responsible for declines and extinction, the fungal pathogen Batrachochytrium dendrobatidis (Bd) has been cited as a major constituent in these events. While the effects of this chytrid fungus have been shown to cause broad scale population declines and extinctions, certain individuals and relict populations have shown resistance. This resistance has been attributed in part to the cutaneous bacterial microbiome. Here, we present the first study characterizing anti-Bd bacterial isolates from amphibian populations in Costa Rica, including the characterization of two strains of Serratia marcescens presenting strong anti-Bd activity. Transcriptome sequencing was utilized for delineation of shifts in gene expression of the two previously uncharacterized strains of S. marcescens grown in three different treatments comprising Bd, heat-killed Bd, and a no Bd control. These results revealed up- and down-regulation of key genes associated with different metabolic and regulatory pathways. This information will be valuable in continued efforts to develop a bacterial-based approach for amphibian protection as well as providing direction for continued mechanistic inquiries of the bacterial anti-Bd response.
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    Characterization of the Skin Microbiota of the Cane Toad Rhinella cf. marina in Puerto Rico and Costa Rica
    (2017) Abarca Alvarado, Juan Gabriel; Zúñiga Chaves, Ibrahim; Ortiz Morales, Gilmary; Lugo, Armando; Víquez Cervilla, Mariel; Rodríguez Hernández, Natalia; Vázquez Sánchez, Frances; Murillo Cruz, Catalina; Torres Rivera, Ernesto A.; Pinto Tomás, Adrián A.; Godoy Vitorino, Filipa
    Rhinella marina is a toad native to South America that has been introduced in the Antilles, likely carrying high loads of microorganisms, potentially impacting local community diversity. The amphibian skin is involved in pathogen defense and its microbiota has been relatively well studied, however, research focusing on the cane toad microbiota is lacking. We hypothesize that the skin microbial communities will differ between toads inhabiting different geographical regions in Central America and the Caribbean. To test our hypothesis, we compared the microbiota of three populations of R. cf. marina toads, two from Costa Rican (native) and one Puerto Rican (exotic) locations. In Costa Rica, we collected 11 toads, 7 in Sarapiquí and 4 from Turrialba while in Puerto Rico, 10 animals were collected in Santa Ana. Separate swab samples were collected from the dorsal and ventral sites resulting in 42 samples. We found significant differences in the structure of the microbial communities between Puerto Rico and Costa Rica. We detected as much as 35 different phyla; however, communities were dominated by Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. Alpha diversity and richness were significantly higher in toads from Puerto Rico and betadiversity revealed significant differences between the microbiota samples from the two countries. At the genus level, we found in Santa Ana, Puerto Rico, a high dominance of Kokuria, Niabella, and Rhodobacteraceae, while in Costa Rica we found Halomonas and Pseudomonas in Sarapiquí, and Acinetobacter and Citrobacter in Turrialba. This is the first report of Niabella associated with the amphibian skin. The core microbiome represented 128 Operational Taxonomic Units (OTUs) mainly from five genera shared among all samples, which may represent the symbiotic Rhinella’s skin. These results provide insights into the habitat-induced microbial changes facing this amphibian species. The differences n the microbial diversity in Puerto Rican toads compared to those in Costa Rica provide additional evidence of the geographically induced patterns in the amphibian skin microbiome, and highlight the importance of discussing the microbial tradeoffs in the colonization of new ecosystems
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    Community richness of amphibian skin bacteria correlates with bioclimate at the global scale
    (2019) Kueneman, Jordan G.; Bletz, Molly C.; McKenzie, Valerie J.; Becker, C. Guilherme; Joseph, Maxwell B.; Abarca Alvarado, Juan Gabriel; Archer, Holly Margaret; Arellano, Ana Lisette; Bataille, Arnaud; Becker, Matthew; Belden, Lisa K.; Crottini, Angelica; Geffers, Robert; Haddad, Célio Fernando Baptista; Harris, Reid N.; Holden, Whitney M.; Hughey, Myra C.; Jarek, Michael; Kearns, Patrick Joseph; Kerby, Jacob L.; Kielgast, Jos; Kurabayashi, Atsushi; Longo, Ana V.; Loudon, Andrew H.; Medina, Daniel; Nuñez Navarro, José J.; Perl, R. G. Bina; Pinto Tomás, Adrián A.; Rabemananjara, Falitiana C. E.; Rebollar Caudillo, Eria Alaide; Rodríguez Gomez, Ariel Ricardo; Rollins Smith, Louise A.; Stevenson, Robert; Tebbe, Christoph C.; Vargas Asensio, Juan Gabriel; Waldman, Bruce; Walke, Jenifer Banning; Whitfield, Steven M.; Zamudio, Kelly R.; Zúñiga Chaves, Ibrahim; Woodhams, Douglas C.; Vences, Miguel
    Animal-associated microbiomes are integral to host health, yet key biotic and abiotic factors that shape host-associated microbial communities at the global scale remain poorly understood. We investigated global patterns in amphibian skin bacterial communities, incorporating samples from 2,349 individuals representing 205 amphibian species across a broad biogeographic range. We analysed how biotic and abiotic factors correlate with skin microbial communities using multiple statistical approaches. Global amphibian skin bacterial richness was consistently correlated with temperature-associated factors. We found more diverse skin microbiomes in environments with colder winters and less stable thermal conditions compared with environments with warm winters and less annual temperature variation. We used bioinformatically predicted bacterial growth rates, dormancy genes and antibiotic synthesis genes, as well as inferred bacterial thermal growth optima to propose mechanistic hypotheses that may explain the observed patterns. We conclude that temporal and spatial characteristics of the host’s macro-environment mediate microbial diversity.
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    Genotyping and differential bacterial inhibition of Batrachochytrium dendrobatidis in threatened amphibians in Costa Rica
    (2021-02-02) Abarca Alvarado, Juan Gabriel; Whitfield, Steven M.; Zúñiga Cháves, Ibrahim; Alvarado Barboza, Gilberth; Kerby, Jacob L.; Murillo Cruz, Catalina; Pinto Tomás, Adrián A.
    Amphibians have declined around the world in recent years, in parallel with the emergence of an epidermal disease called chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). This disease has been associated with mass mortality in amphibians worldwide, including in Costa Rica, and Bd is considered an important contributor to the disappearance of this group of vertebrates. While many species are susceptible to the disease, others show tolerance and manage to survive infection with the pathogen. We evaluated the pathogen Bd circulating in Costa Rica and the capacity of amphibian skin bacteria to inhibit the growth of the pathogen in vitro. We isolated and characterized – genetically and morphologically – several Bd isolates from areas with declining populations of amphibians. We determined that the circulating chytrid fungus in Costa Rica belongs to the virulent strain Bd-GPL- 2, which has been related to massive amphibian deaths worldwide; however, the isolates obtained showed genetic and morphological variation. Furthermore, we isolated epidermal bacteria from 12 amphibian species of surviving populations, some in danger of extinction, and evaluated their inhibitory activity against the collection of chytrid isolates. Through bioassays we confirmed the presence of chytrid-inhibitory bacterial genera in Costa Rican amphibians. However, we observed that the inhibition varied between different isolates of the same bacterial genus, and each bacterial isolation inhibited fungal isolation differently. In total, 14 bacterial isolates belonging to the genera Stenotrophomonas, Streptomyces, Enterobacter, Pseudomonas and Klebsiella showed inhibitory activity against all Bd isolates. Given the observed variation both in the pathogen and in the bacterial inhibition capacity, it is highly relevant to include local isolates and to consider the origin of the microorganisms when performing in vivo infection tests aimed at developing and implementing mitigation strategies for chytridiomycosis.