AISLAMIENTO Y SELECCIÓN DE ACTINOMICETOS RIZOSFÉRICOS CON ACTIVIDAD ANTAGONISTA A FITOPATÓGENOS DE LA PAPA (Solanum tuberosum spp. andigena)

ISOLATION AND SELECTION OF RHIZOSPHERIC ACTINOMYCETES WITH ANTAGONISTIC ACTIVITY AGAINST POTATO PHYTOPATHOGENS  (Solanum tuberosum spp. andigena)

Junior Caro Castro[1], Claudia Mateo Tuesta[1], Jessica Cisneros Moscol[1], Nadia Galindo Cabello[1] y Jorge León Quispe^1,[2]

Resumen

El cultivo de la papa se ve afectado por una gran cantidad de patógenos que disminuyen su calidad y productividad. Uno de los métodos de control de estos fitopatógenos es mediante el uso de microorganismos antagonistas, en especial aquellos que se aíslan de la comunidad microbiana presente en la rizósfera. En este trabajo, se aislaron 49 cepas de actinomicetos y se evaluaron sus capacidades antagonistas frente a fitopatógenos que afectan a Solanum tuberosum. El 26.5% presentó capacidad antagónica frente a Pectobacterium carotovorum, el 69.4% a Fusarium sp., el 44.9% a Lasiodiplodia sp., el 55.1% a Rhizoctonia solani y el 46.9% a Phytophthora infestans. Cultivos de dos actinomicetos seleccionados (AND 12 y AND 24) fueron tratados con acetato de etilo, diclorometano, hexano y butanol, cuyos extractos crudos mostraron actividad antimicrobiana, siendo el extracto obtenido con acetato de etilo el más importante por presentar mayor espectro de actividad inhibitoria. Las cepas seleccionadas se identificaron por análisis filogenético del gen del ARNr 16S como miembros del género Streptomyces. Los actinomicetos rizosféricos, por su probada capacidad antagonista demostrada en el presente estudio, podrían ser considerados como potenciales candidatos a ser utilizados en programas de control de patógenos que afectan a la papa.

Palabras clave: Streptomyces, microorganismos de suelo, patógenos de la papa, compuestos bioactivos, antagonismo.

 

Abstract

Potato crops are affected by a great number of pathogens that decrease their quality and productivity. One way of controlling these phytopathogens is through the use of antagonistic microorganisms, especially those isolated from the microbial community located in the rhizosphere. In this study, 49 strains of actinomycetes were isolated and their antagonist capacity against phytopathogens that affect Solanum tuberosum was assessed. 26.5% showed antagonist activity against Pectobacterium carotovorum, 69.4% against Fusarium sp., 44.9% against Lasiodiplodia sp., 55.1% against Rhizoctonia solani and 46.9% against Phytophthora infestans. Cultures of two selected actinomycetes (AND 12 and AND 24) were treated with ethyl acetate, dichloromethane, hexane and butanol, whose crude extracts showed antimicrobial activity, being the most important the extract obtained with ethyl acetate due to its greater spectrum of inhibitory activity. The selected strains were identified by phylogenetic analysis of the 16S rRNA gene as members of the genus Streptomyces. Due to their antagonist capacity demonstrated in the present study, rhizospheric actinomycetes could be considered as potential candidates to be used in pathogen control programs that affect potatoes.

Key words: Streptomyces, soil microorganisms, potato pathogens, bioactive compounds, antagonism.