Molecular characterization and in situ detection of bacterial communities associated with rhizosphere soil of high altitude native Poaceae from the Andean Puna region

Puna is a harsh bio-geographical region in South America that characterized by distinct plant diversity, high aridity and irradiance. In the present study, rhizospheric bacterial communities were analyzed along an altitudinal gradient in this region while considering the different photosynthesis pathways (C3/C4) of the native grasses. This analysis included cultivation-dependent and -independent approaches such as PCR-DGGE analysis of the 16S rRNA genes and FISH. DGGE revealed that the band richness differed along the altitudinal gradient, but that it did not differ significantly among plants with different metabolic pathways. Overall, we found that Bacillus and Pseudomonas were the dominant phylotypes based on the DGGE analysis. Additionally, nearly 80% of the species identified by PCR were also identified using the cultivation method. FISH analysis revealed that the Gammaproteobacteria and Actinobacteria were the dominant bacterial groups at most sites, followed by Archaea. Finally, low bacterial diversity was detected in samples collected from all heights, possibly due to the harsh environment. Overall, evaluation of the results obtained using the two different approaches revealed that the culture method is efficient for screening of the bacterial community in Puna rhizospheric soils. Additionally, we discuss possible effects of Puna rhizospheric bacteria on the protection of native grasses and nutrient capture.