Diversity of root endophytic bacteria associated with the date palm tree from the south of Tunisia

Endophytes are the microbes colonizing the internal tissues of plants. These microbes are able to establish different types of interaction with their host, such as mutualism, commensalism and symbiosis. The present work deals with the identification of entophytic bacteria from the palm date routs sampled in different oasis located in the south of Tunisia and the determination of the prevalent species adapted to such extreme conditions. The molecular characterization of isolates, based on the analysis of the intergenic-spacer amplification profiles, showed the differentiation of 16 different haplotypes. These groups reflect the diversity of isolates within the different samples and the spatial diversity inherent to the sampling region. The identification of these isolates by 16S rDNA sequençing showed the prevalence of Proteobacteria, Actinobacteria and Bacteroidetes groups, including the species of Pseudomonas brassicacearum, Yersinia kristensenii, Ranella aquatilis, Pantoea ananatis, Microbacterium phyllosphareae and Buttiauxella noakiae. Screening of the strains for plant growth promoting properties showed that some of the strains were able to fix nitrogen, to produce high amounts of auxins and/or to express anti-fungal activity inhibiting the growth of Botrytis cineria and Aspergillus niger. This study showed the importance of these bacteria for potential application in the biocontrol of phytopathogenic fungi and in promoting the growth of plants.