Aislamiento y caracterización de bacterias endófitas del manglar (Avicennia germinans) con capacidad de tolerar altas concentraciones de NaCl
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Fecha
2022
Autores
Rolong Orozco, Dani Alexander
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Ediciones Universidad Simón Bolívar
Facultad de Ciencias Básicas y Biomédicas
Facultad de Ciencias Básicas y Biomédicas
Resumen
Los bosques de manglar son ecosistemas que se desarrollan en zonas mareales, intermales y ribereñas de las costas tropicales y subtropicales, poseen una gran biodiversidad de fauna, flora y de microorganismos. Gracias a su particular fisiología y reproducción, los manglares pueden adaptarse a condiciones extremas, como medios acuáticos de alta salinidad (Vera & Martínez, 2013). Los mangles son altamente relevantes, ya que proporcionan las fuentes primarias de la red trófica, dado que, al generar hojarasca, benefician a varios peces y moluscos durante la fase sexual de su ciclo de vida, convirtiéndose en un sitio apto de reproducción de peces y de crustáceos tales como camarones, jaibas, bagres, pargos, entre otros (Ezcurra et al., 2009). Esto último, genera que la economía de gran parte de la población asentada en estos territorios de la costa se beneficie, puesto que su economía está basada en la pesca artesanal, recolección de moluscos, recolección y venta de crustáceos, acuicultura y el turismo (Von Prahl et al., 1990). Los manglares son considerados por la ONU como uno de los mayores captadores de gases de efecto invernadero como lo es el CO2 (Lee et al., 2014; Polidoro et al., 2010) convirtiéndolos en un ecosistema indispensable para afrontar los efectos del cambio climático. Además, al ser ricos en microorganismos y compuestos bioactivos, se emplean en la industria farmacéutica, biotecnológica, agrícola, etc (Bolívar-anillo et al., 2020; Castro et al., 2014; Wu et al., 2008; Xu, 2015). No obstante, a pesar de todos los beneficios que brindan, se encuentran en constante amenaza tanto por impactos antrópicos y naturales, ocasionando graves efectos desde el punto de vista ambiental, social y económico. La Ciénaga de Balboa ubicado en el municipio de Puerto Colombia, presenta características ambientales las cuales permiten el desarrollo de los manglares. Dichos manglares son un ecosistema representativo y poseen un gran valor ecológico y económico para el municipio, lamentablemente dicho ecosistema en los últimos años se ha venido viendo afectados por factores antrópicos y naturales dentro del cual la alteración de la hidrología del bosque, debido a la falta de aportes de agua dulce causada por el encausamiento de los arroyos ha generado un progresivo aumento de la salinidad de los suelos y por ende limita desde hace 10 a 20 años, el crecimiento de plántulas y árboles de mangle (Sánchez et al; 2019). Recientemente se ha documentado sobre el papel fundamental de los microorganismos asociados a la rizosfera del manglar, como los responsables de la adaptación y sobrevivencia de las plantas de mangle, a condiciones extremas de los sedimentos estuarinos en el cual se desarrollan, esto último gracias a la interacción dada por la liberación de exudados ricos en vitaminas y azúcares de las raíces del mangle (Bashan & Holguín; 2002). Por lo tanto, el objetivo de este estudio fue aislar y caracterizar bacterias endófitas del manglar con capacidad de tolerar altas concentraciones de NaCl y evaluar su capacidad de promoción de crecimiento vegetal, para proponerlas como alternativa para la reforestación de los bosques de manglar. La evaluación de tolerancia a diferentes concentraciones de NaCl reveló que todas las bacterias toleran de 0% a 15% y solo una fue capaz de soportar hasta 20% de sal. Igualmente, se detectó que el 42.8% de las cepas aisladas presentan actividad proteolítica, el 57.1% posee actividad amilolítica, ninguna de las cepas posee la capacidad de solubilizar fosfato ni potasio y el 71.4% de las bacterias son capaces de fijar nitrógeno atmosférico. Esta investigación preliminar demuestra que las bacterias endófitas del manglar de la Ciénaga de Balboa pueden ser empleadas para aumentar la tolerancia de las plántulas y árboles de mangle a estrés salino y en la promoción de crecimiento vegetal y proponerlas como una posible estrategia de reforestación de dicho ecosistema. Sin embargo, es necesario que se exploren aún más los manglares y de esta manera conocer el potencial uso que tiene el microbiota endófita de este y la contribución directa en la conservación y recuperación del mismo.
Mangrove forests are ecosystems that develop in tidal, intertidal and riparian zones of the tropical and subtropical coasts, they possess a great biodiversity of fauna, flora and microorganisms. Thanks to their particular physiology and reproduction, mangroves can adapt to extreme conditions, such as high salinity aquatic environments (Vera & Martínez, 2013). Mangroves are highly relevant because they provide the primary sources of the food web, since, by generating litter, they benefit several fish and molluscs during the sexual phase of their life cycle, becoming a suitable breeding site for fish and crustaceans such as shrimps, crabs, catfish, snappers, among others (Ezcurra et al., 2009). The latter, generates that the economy of a large part of the population settled in these coastal territories benefits, since its economy is based on artisanal fishing, shellfish collection, crustacean collection and sale, aquaculture and tourism (Von Prahl et al., 1990). Mangroves are considered by the UN as one of the largest collectors of greenhouse gases such as CO2 (Lee et al., 2014; Polidoro et al., 2010) making them an indispensable ecosystem to face the effects of climate change. In addition, being rich in microorganisms and bioactive compounds, they are used in the pharmaceutical, biotechnology, agricultural, etc (Bolivar-anillo et al., 2020; Castro et al., 2014; Wu et al., 2008; Xu, 2015). However, despite all the benefits they provide, they are constantly threatened by both anthropic and natural impacts, causing serious environmental, social and economic effects. The Ciénaga de Balboa located in the municipality of Puerto Colombia, presents environmental characteristics that allow the development of mangroves. These mangroves are a representative ecosystem and have great ecological and economic value for the municipality, unfortunately this ecosystem in recent years has been affected by anthropogenic and natural factors within which the alteration of the hydrology of the forest, due to the lack of freshwater inputs caused by the channeling of streams has generated a progressive increase in soil salinity and therefore limited for 10 to 20 years, the growth of seedlings and mangrove trees (Sánchez et al; 2019). It has recently been documented the fundamental role of microorganisms associated with the rhizosphere of the mangrove, as those responsible for the adaptation and survival of mangrove plants, to extreme conditions of the estuarine sediments in which they develop, The latter thanks to the interaction given by the release of exudates rich in vitamins and sugars from the roots of the mangrove (Bashan & Holguín; 2002). Therefore, the aim of this study was to isolate and characterize endophytic mangrove bacteria with the ability to tolerate high concentrations of NaCl and evaluate their ability to promote plant growth, to propose them as an alternative for the reforestation of mangrove forests. Tolerance assessment at different concentrations of NaCl revealed that all bacteria tolerate 0% to 15% and only one was able to support up to 20% salt. Likewise, it was detected that 42.8% of the isolated strains have proteolytic activity, 57.1% have amylolytic activity, none of the strains has the ability to solubilize phosphate or potassium and 71.4% of the bacteria are able to fix atmospheric nitrogen. This preliminary research shows that endophytic bacteria from the mangrove of Balboa Swamp can be used to increase the tolerance of saplings and mangrove trees to saline stress and to promote plant growth and propose them as a possible Reforestation strategy for this ecosystem. However, it is necessary to further explore the mangroves and in this way know the potential use that the endophyte microbiota has of this and the direct contribution in its conservation and recovery
Mangrove forests are ecosystems that develop in tidal, intertidal and riparian zones of the tropical and subtropical coasts, they possess a great biodiversity of fauna, flora and microorganisms. Thanks to their particular physiology and reproduction, mangroves can adapt to extreme conditions, such as high salinity aquatic environments (Vera & Martínez, 2013). Mangroves are highly relevant because they provide the primary sources of the food web, since, by generating litter, they benefit several fish and molluscs during the sexual phase of their life cycle, becoming a suitable breeding site for fish and crustaceans such as shrimps, crabs, catfish, snappers, among others (Ezcurra et al., 2009). The latter, generates that the economy of a large part of the population settled in these coastal territories benefits, since its economy is based on artisanal fishing, shellfish collection, crustacean collection and sale, aquaculture and tourism (Von Prahl et al., 1990). Mangroves are considered by the UN as one of the largest collectors of greenhouse gases such as CO2 (Lee et al., 2014; Polidoro et al., 2010) making them an indispensable ecosystem to face the effects of climate change. In addition, being rich in microorganisms and bioactive compounds, they are used in the pharmaceutical, biotechnology, agricultural, etc (Bolivar-anillo et al., 2020; Castro et al., 2014; Wu et al., 2008; Xu, 2015). However, despite all the benefits they provide, they are constantly threatened by both anthropic and natural impacts, causing serious environmental, social and economic effects. The Ciénaga de Balboa located in the municipality of Puerto Colombia, presents environmental characteristics that allow the development of mangroves. These mangroves are a representative ecosystem and have great ecological and economic value for the municipality, unfortunately this ecosystem in recent years has been affected by anthropogenic and natural factors within which the alteration of the hydrology of the forest, due to the lack of freshwater inputs caused by the channeling of streams has generated a progressive increase in soil salinity and therefore limited for 10 to 20 years, the growth of seedlings and mangrove trees (Sánchez et al; 2019). It has recently been documented the fundamental role of microorganisms associated with the rhizosphere of the mangrove, as those responsible for the adaptation and survival of mangrove plants, to extreme conditions of the estuarine sediments in which they develop, The latter thanks to the interaction given by the release of exudates rich in vitamins and sugars from the roots of the mangrove (Bashan & Holguín; 2002). Therefore, the aim of this study was to isolate and characterize endophytic mangrove bacteria with the ability to tolerate high concentrations of NaCl and evaluate their ability to promote plant growth, to propose them as an alternative for the reforestation of mangrove forests. Tolerance assessment at different concentrations of NaCl revealed that all bacteria tolerate 0% to 15% and only one was able to support up to 20% salt. Likewise, it was detected that 42.8% of the isolated strains have proteolytic activity, 57.1% have amylolytic activity, none of the strains has the ability to solubilize phosphate or potassium and 71.4% of the bacteria are able to fix atmospheric nitrogen. This preliminary research shows that endophytic bacteria from the mangrove of Balboa Swamp can be used to increase the tolerance of saplings and mangrove trees to saline stress and to promote plant growth and propose them as a possible Reforestation strategy for this ecosystem. However, it is necessary to further explore the mangroves and in this way know the potential use that the endophyte microbiota has of this and the direct contribution in its conservation and recovery
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Palabras clave
Avicennia germinans, Bacterias endófitas, Puerto Colombia, Manglares, Ciénaga de Balboa, Avicennia germinans, Endophytic bacteria, mangroves
