Isolation and identification of actinomycetes associated with the rhizospheric soil of Machaeranthera gypsophila (Gypsum plant) with potential antagonistic activity against phytopathogenic microorganisms.

Abstract

 The gypsum plant (Machaeranthera gypsophila) is a shrub adapted to grow in gypsophilous soils within the dunes of the Cuatrociénegas Valley. In recent years, the rhizosphere of plants in various ecosystems have been the subject of bioprospecting activities in the targeted search for new sources of actinomycetes with biotechnological importance. In this work, 43 actinomycete strains were isolated from samples of rhizosphere soil of Machaerentera gypsophila. Through a discriminatory analysis using colonial morphology and color production in the culture medium and mycelium, it was possible to reduce them to 24 strains or morphotypes. Of the total number of identified morphotypes, 12 showed multiple abilities in cellulolytic, xylanolytic, pectinolytic and phosphate solubilizing enzymatic activities. Likewise, of these 12 morphotypes, 10 presented antagonism to the fungus Sporisorium reilianum and to the phytopathogenic bacteria Pseudomonas viridiflava, Pseudomonas savastanoi pv. nerii and Xantomonas translucens pv. undulosa. According to the percentages of inhibition of the phytopathogens and potency indices of the enzymatic activity, 12 actinomycetes were selected for molecular identification of the partial sequencing of the 16S rDNA gene. The partial sequences of each actinomycete were analyzed for similarity in the GenBank and by phylogenetic construction, showing as a result that they belong to the genera Streptomyces and to the species thinghiriensis, tendae, rochei and sp., which are used as plant growth promoters and biocontrol agents.