Since global food insecurity is one of the major problems faced by humanity, there is a necessity to increase plant productivity. For this, biofungicides and biofertilizers present an ecologically... Show moreSince global food insecurity is one of the major problems faced by humanity, there is a necessity to increase plant productivity. For this, biofungicides and biofertilizers present an ecologically friendly alternative to their chemical counterparts. Among these bioinoculants, endophytic bacteria with plant growth promotion and biocontrol abilities are the most promising candidates due to their ability to colonize the plant__s interior and establish a stable, long-lasting relationship with a plant. In this thesis, I succeeded in the isolation of many beneficial endophytic strains. Among them, Bacillus subtilis HC8 isolated from giant hogweed proved to be the most versatile promising bioinoculant since it expressed its beneficial effect on diverse plants under different growth conditions. It was also shown that this strain, so far, is the only endophytic Bacillus __ and one out of a few Bacillus strains __ which is capable of producing excessively high levels of a large variety of lipopeptide antibiotics. Attempts were also made to shed light on the endophytic lifestyle of several strains. This resulted in finding L-arabinose, a carbon source which might be important for endophytic pseudomonads in cucumber plants. This and other (yet-) unidentified traits could contribute to the complex interaction of endophytic bacteria and plants Show less