Bacterias rizosféricas asociadas a Dryopteris pseudofilix-mas (Dryopteridaceae) en el Monte Tláloc, México

Introduction: Plant roots harbor communities of bacteria that can provide benefits to their host through the production of phytohormones, phosphate solubilization, and nitrogen fixation. In Mexico, there are few studies on the richness and diversity of rhizobacteria communities associated with ferns. Objective: To analyze and identify the functional groups of bacteria from the rhizosphere of Dryopteris pseudofilix-mas in Mount Tlaloc, Mexico. Methods: Rhizospheric soil from D. pseudofilix-mas was collected at four sites where this fern occurs naturally. Bacterial populations were quantified by the plate count and dilution method. The isolated strains were characterized and identified using the 16S rDNA gene. Physical and chemical characteristics of the soil were determined and data of soil moisture, temperature and light in the canopy were collected. Results: The total bacteria population was from 30.1 to 92.3 x 104 CFU g-1 soil. Soil pH and phosphorus content influenced the density of bacterial populations. About 120 bacterial strains were isolated, 101 were Gram-negative and 19 Gram-positive. The isolated strains belonged to 20 genera, being the most abundant Pseudomonas and Bacillus. The Sørensen index indicates that the species of bacteria are similar in the four sites; Pseudomonas jessenii was present in the four sites. The bacterial strains presented more than one plant growth promoting activity, being the group of nitrogen fixers the most abundant. Conclusions: The rhizosphere of D. pseudofilix-mas harbors diverse groups of functional bacteria that could potentially be used in biotechnology for ecological restoration or agricultural purposes. The bacterial population of the four sites was dominated mainly by Pseudomonas and Bacillus.