Changes in the soil bacterial community along a pedogenic gradient

Current research on the influence of environmental and physicochemical factors in shaping the soil bacterial structure has seldom been approached from a pedological perspective. We studied the bacterial communities of eight soils selected along a pedogenic gradient at the local scale in a Mediterranean calcareous mountain (Sierra de María, SE Spain). The results showed that the relative abundance of Acidobacteria, Canditate division WPS-1, and Armatimonadetes decreased whereas that of Actinobacteria, Bacteroidetes, and Proteobacteria increased from the less-developed soils (Leptosol) to more-developed soils (Luvisol). This bacterial distribution pattern was also positively correlated with soil-quality parameters such as organic C, water-stable aggregates, porosity, moisture, and acidity. In addition, at a lower taxonomic level, the abundance of Acidobacteria Gp4, Armatimonadetes-gp4, Solirubrobacter, Microvirga, Terrimonas, and Nocardioides paralleled soil development and quality. Therefore, our work indicates that the composition of bacterial populations changes with pedogenesis, which could be considered a factor influencing the communities according to the environmental and physicochemical conditions during the soil formation.This work was financed by the Ministry of Economy and Competitiveness of Spain, co-financed with European Regional Development Funds, research grant: CGL2015-71709-R (MINECO/FEDER) and fellowship contract PEJ-2014-A-62057. I.M. acknowledges for funding received from the Marie Curie Intra-European Fellowship (FP7-PEOPLE-2013-IEF, Proposal n° 623393), the UAL HIPATIA Programme from the University of Almería and the Ramon y Cajal (RyC-2016-21191) Programme from the Ministry of Economy and Competitiveness of Spain (MINECO). We thank Mr. David Nesbitt for improving the English editing.Peer Reviewe