Arbuscular Mycorrhizal Fungi and Rhizospheric Bacteria Diversity Along an Altitudinal Gradient in South American Puna Grassland

Abstract

Rhizospheric soil samples were taken from Puna native grasses along an altitudinal gradient. Biodiversity of arbuscular mycorrhizal fungi(AMF) and associated bacteria was analyzed considering altitude and grasses metabolic type. Cultivation-dependent approaches were applied in order to obtain further information about the phylogeny of the dominating cultivable aerobic-heterotrophic bacteria communities present in rhizospheric soil samples. In average, the bacterial count ranged between 1,30 x 10 2 and 8,66 x 10 4 CFU x g of dry weight of soil. Individual bacterial colonies of aerobic heterotrophic bacteria grown on R2A medium were morphologically grouped and identified as typical soil bacteria belonging to the genera Bacillus,Pseudomonas and Arthrobacter. Ten AMF taxa were found: Acaulospora sp., A. laevis, A. spinosa, Gigaspora sp., Gi. ramisporophora, Glomus sp., Gl. aggregatum, Gl. ambisporum, Gl. sinuosum and Scutellospora biornata. AMF richness and density were negatively correlated with altitude. AMF diversity was influenced with increasing altitude.