Screening and biochemical identification of Tef (Eragrostis tef Zucc.) Trotter) endophytic bacterial species with plant-growth-promoting, biotic and abiotic stress tolerance properties

Endophytic bacteria play many important beneficial roles in the metabolism and physiology of the host plants, including fixing atmospheric nitrogen, solubilizing phosphates, synthesizing phytohormones, sequestrating iron, suppression of the ethylene production, and inhibiting pathogens. The present study was conducted to screen and identify endophytic bacterial species with plant growth-promotion, biotic and abiotic stress tolerance properties to develop bio inoculants. For this purpose, root and seed samples of different cultivated tef varieties were collected. A total of 195 pure endophytic bacterial colonies were isolated and screened for PGP traits, biotic and abiotic stress tolerance factors. Fourteen endophytic bacterial species or strains were identified using the Biolog microbial identification system. Among the identified endophytes, the majority of them utilized different carbon sources tagged on microplates. Three potential endophytic bacterial species or strains were evaluated for seed germination and seedling growth ability using tef seeds. Tef seeds inoculated with potential endophytes showed 100 % germination performance on 3 to 4 days after inoculation. An increase in mean shoot and roots length of the inoculated seeds were observed up to 3 and 2.6 cm respectively. Vigor index of seedling was measured from 460 to 520 on the last day of the experiment. These promising identified tef endophytic bacterial species or strains having PGP, biotic and abiotic stress tolerance properties could be candidate organisms for the development of microbial inoculants as single strain or consortia. This strategy would work towards solving the problem of over-utilizing chemical fertilizers, and reducing environmental pollution while increasing the yield and productivity of tef crops and other agricultural plants.