Genetic diversity and salt tolerance of bacterial communities from two Tunisian soils

Microbial ecology studies on and soils are particularly important for the analysis of biological functions during desertification. Although much is known about the and saline flora, few researches have directly compared the bacterial communities of saline and soils with cultivated soils in Northern Africa. Bacterial communities present in two soils from Soliman (north of Tunisia), one salty and neglected, and the other cultivated, were investigated by using both cultivation dependent and independent approaches. The first approach was used to assess the presence of salt tolerant bacteria and the relationships among salt (NaCl) resistance phenotype, soil characteristics and phylogenetic assignment of strains. Total community ana lysis, performed by T-RFLP on total DNA, was carried out to investigate the relationships between total community fingerprinting with cultivated isolates diversity. The cultivated isolates from salty soil were more genetically diverse, harbouring strains that can grow at high salt concentration. Moreover, the salt resistance of isolates was found not to be related to-any particular phylogenetic group, being widespread among isolates belonging to different bacterial subdivisions. Ribotype richness, evaluated as number of different T-RFLP bands (TRFs), was shown to be higher in the agricultural soil than in the salty soil and several agricultural soil-specific TRFs were detected.