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Plants live in association with complex populations of microorganisms, including Plant Growth-Promoting Rhizobacteria (PGPR) that confer to plants an improved growth and enhanced stress tolerance. This large and diverse group includes endophytic bacteria that are able to colonize the internal tissues of plants. In the present study, we have isolated a nonrhizobial species from surface sterilized root nodules of Retama monosperma, a perennial leguminous species growing in poor and high salinity soils. Sequencing of its genome reveals this endophytic bacterium is a Bacillus megaterium strain (RmBm31) that possesses a wide range of genomic features linked to plant growth promotion. Furthermore, we show that RmBm31 is able to increase the biomass and positively modify the root architecture of seedlings of the model plant species Arabidopsis thaliana both in physical contact with its roots and via the production of volatile organic compounds. Lastly, we investigated the molecular mechanisms implicated in RmBm31 plant beneficial effects by carrying out a transcriptional analysis on a comprehensive set of phytohormone-responsive marker genes. Altogether, our results demonstrate that RmBm31 displays plant growth-promoting traits of potential interest for agricultural applications.

The objective of this study was to isolate and select Lactobacillus strains with probiotic features for a potential use as starter for the preservation of animal feed. Olives, cow’s and camel’s milk, butter, beer drech and maize silage were used as isolation sources. Molecular identification using 16S rRNA gene sequencing identified four isolates of Lactobacillus plantarum and three of Lactobacillus fermentum. The different screening tests revealed that four strains: Lactobacillus plantarum OV13, Lactobacillus sp. OV15, Lactobacillus fermentum E161 and Lactobacillus sp. E631 are the best probiotic candidates , based on the results of their tolerance to acidic pH between 2 and 3.5, to 0.3% bile, to artificial gastric conditions for 18h of incubation , to their antibiotics resistance, their inhibition power on pathogenic bacteria (Pseudomonas sp., Staphylococcus aureus , Escherichia coli and Listeria ivanovii), and finally to their adhesion capacity to intestinal epithelial cells. The selected probiotic strains are considerate as good candidates for further investigation and should be tested, in vivo, to elucidate their potential health benefits on the animal performance as novel probiotic starters.