Aims This research aimed to isolate and characterize nonrhizobial endophytic bacteria from root nodules of Medicago sativa L. and Lotus corniculatus L. with plant growth-promoting characteristics and to test its activity in a pot experiment with acid soil. Methods and Results Out of 44 nonrhizobial isolates, the majority exhibited indole-3-acetic acid (IAA) production; 29 produced siderophores, few isolates performed phosphate solubilization and/or produced lytic enzymes, while 30% of isolates showed notable antifungal activity. The most promising strains were identified as members of Bacillus, Pseudomonas and Serratia genera, based on 16S rRNA. Bacillus megaterium DZK1BH exhibited the overall best attributes for plant growth promotion and positively influenced the growth of L. corniculatus and Dactylis glomerata. Conclusions Root nodule endophytic B. megaterium DZK1BH could potentially be used as a biofertilizer for growing L. corniculatus L. and D. glomerata L. in acid soils, while Bacillus mojavensis L3 is a candidate for further antifungal potential investigation. Significance of Impact of the Study The use of root nodule endophytic bacteria with PGP traits may find its future application in organic agriculture, as their utilization could decrease the use of chemical fertilizers and pesticides and simultaneously promote plant growth, especially in soils with low production quality.

Application of liquid microbial inoculants on legume seeds is a sustainable agricultural practice that can improve plant nutrient uptake and increase crop productivity. Inoculants should provide long-term survival of rhizobia in the final product and after application, to legume seeds. Ten different medium formulations of microbial inoculants were examined (yeast mannitol broth with the addition of agar, sodium-alginate, calcium chloride, glycerol or ferric chloride and combinations thereof) for the survival of the efficient nitrogen-fixing rhizobium, Sinorhizobium (Ensifer) meliloti L3Si strain. The most suitable liquid inoculant for survival of L3Si during a storage time of 150 days was the medium formulation containing glycerol in combination with agar or sodium-alginate. Alfalfa seeds were pre-inoculated with four formulations (yeast mannitol broth (YMB), YMB with agar (1 g L-1), YMB with 1 or 5 g L-1 sodium-alginate) for up to three months. Seeds pre-inoculated and stored for one month produced successful alfalfa plants. The nitrogen content in alfalfa obtained from pre-inoculated seeds one month before sowing was adequate and ranged from 3.72-4.19%. Using S. meliloti-based liquid inoculants for alfalfa and application of the pre-inoculation technique can increase the quality of alfalfa crops and reduce cultivation cost.