Artículos científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/14821

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Effect of metal concentration on growth and luminescence of luminous bacteria straims isolated from golfo de Nicoya, Costa Rica
(Universidad Nacional (Costa Rica), 2021-01) Vega-Corrales, Luis; Marín, Carolina
Luminescence in bacteria is catalyzed by luciferase. When these microorganisms are exposed to toxic substances, the bioluminescent enzyme system can be inhibited. The objective of this study was to analyze the potential that these microorganisms offer as native bioindicators of coastal marine pollution. The dynamics of luminescence intensity by visual classification and the effect of metal concentration on the growth and luminescence of 25 strains of luminescent bacteria, isolated during 2016 from seawater samples from the gulf of Nicoya, Costa Rica, was evaluated by the disk diffusion method. The sensitivity of each strain to different concentrations (0.1, 0.5 and 1 mg mL-1) of Cd, Cu, Cr, Pb and Zn was determined by its bioluminescent phenotype. In susceptible strains, a range of metal concentrations less than the growth inhibitory concentration affected the expression of luminescence. Strains with intense luminescence and defined zones of luminescence inhibition were considered to have greater potential as native bioindicators for monitoring environmental toxicity. More studies are required to determine the minimum concentrations that inhibit growth and luminescence with respect to the tested metals and other potentially toxic substances for the coastal marine ecosystems of Costa Rica.
First report on the presence of microplastics in bovine and porcine livers from Costa Rica
(Universidad Nacional de Costa Rica, 2026) Soto Barrientos, Natalia; Ulate Naranjo, Karol; Víquez Murillo, Catalina; García Rojas, Andrea
[Objective] Given the ease with which microplastics (MPs) are transported, ecosystems around the world are being polluted with these particles. Reports on the presence of MPs in marine organisms are alarming, but research on the presence of such particles in the terrestrial environment is still very scarce in Costa Rica, and even scarcer for the Central American region. Given this situation, it was considered urgent to carry out a multidisciplinary investigation to obtain information about MP contamination of animal tissues destined for human consumption. [Methodology] Samples of 20 livers from bovines and 18 from porcine, were purchased from local markets in 4 of the main meat-producing regions of the country. All samples were chemically digested with potassium hydroxide for the extraction of microplastic particles. [Results] Ninety percent of the bovine livers were positive for the presence of MPs, as were 83.3% of the porcine livers. Fibers and films, ranging from 220 μm to 4.5 mm, most of which were blue-green in color, were found. [Conclusions] These findings provide information about the types of MPs that were present in the samples analyzed, but they do not aid in determining the exact origin of the particles and how they reached livers of the animals. Nonetheless, it is now clear that these pollutants are reaching human and animal populations, and since adverse effects have already been reported due to the presence of these particles in the human body, these results must be taken into account by healthcare professionals when considering any emerging diseases
Identificación de cuatro especies de Clupeiformes (Actinopterygii) mediante análisis de secuencias de ADN mitocondrial en áreas de explotación pesquera del Golfo de Nicoya, Costa Rica
(Universidad Nacional, Costa Rica, 2021-01) Sancho Blanco, Carolina; Hernández Noguera, Luis; Vega Alpízar, Luis; Soto Rojas, Rosa Lidia; Umaña Castro, Rodolfo
Las sardinas junto con las anchovetas constituyen unos de los grupos de mayor importancia en la pesquería del golfo de Nicoya. Son alimento para peces de mayor tamaño y aves marinas, por tanto, no solo sufren explotación pesquera, sino también presentan altas tasas de mortalidad natural. Debido a la importancia comercial y ecológica que representan estas especies, es necesario contar con una correcta identificación taxonómica, principalmente para la elaboración de estudios pesqueros. Antes, la determinación de especies de peces se fundamentaba únicamente en características morfológicas externas, sin embargo, no siempre es posible, debido a su similitud morfológica, por lo que el uso combinado de datos morfológicos junto con los genéticos basado en genes mitocondriales puede contribuir en su reconocimiento. Históricamente, estudios taxonómicos han agrupado a las especies O. libertate, O. medirastre y O. bulleri como integrantes del complejo Opisthonema spp., dada la gran similitud de forma. Mientras, para la familia Engraulidae, las indagaciones taxonómicas son escasas. En el presente trabajo, se identificaron molecularmente especies del complejo Opisthonema spp. y una especie del género Cetengraulis sp., colectadas entre junio y diciembre del 2017, mediante secuenciación de genes mitocondriales: COI, Ctyb y 16S ARNr. Los hallazgos confirmaman, con datos moleculares, la identidad y presencia de tres especies del complejo Opisthonema spp. y una especie de anchoveta, localizadas en zonas de explotación pesquera en el golfo de Nicoya, Costa Rica, información que facilita el uso y manejo de estos recursos pesqueros en un área marina de importancia comercial en el país
Identification of biosurfactant-producing fungi isolated from the Costa Rican mangrove
(Universidad Nacional de Costa Rica, 2026) Valerio Aguilar, kenneth; Fallas Méndez, Adriana; Rodríguez Rodríguez, Jorengeth; Singh Thakur, Samrendra; Solano-González, Stefany
In Costa Rica, mangrove potential has not been studied from a biotechnological perspective, despite reports from other latitudes of promising fungi associated with these ecosystems, including biosurfactant potential. These molecules are primarily used in industry as emulsifiers; however, studies indicate their potential in healthcare, pharmaceutical, and agricultural applications. [Objective] This study aimed to screen and preliminarily identify fungal strains capable of producing biosurfactants by implementing a set of effective, low-cost, straightforward assays for future exploitation. [Methodology] Five fungal strains from the Manuel Antonio mangrove in Puntarenas, Costa Rica, were isolated, molecularly identified, and assessed for biosurfactant production utilizing the crude biosurfactant broth. The drop collapse test, oil displacement test, emulsification index, and hemolysis tests were assessed. [Results] The use ofcrude biosurfactant broth minimized the cost and time required for purifications, which enabled the reduction of screening time for all fermentations. Isolate MP4 displayed, overall and consistently, better performance than the other strains evaluated for growth and biosurfactant production assays, especially for the emulsification index and blood hemolysis test. ITS and LSU molecular markers were analyzed, and MP4 was taxonomically assigned as Trichoderma sp.; however, it was shown to be closely related to T. melanomagnum. [Conclusions] Results emphasize the unexplored potential of mangrove resources in Costa Rica for biosurfactant production, and although preliminary, they demonstrate the value of conducting future comprehensive studies to evaluate this fungal potential.

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