Isolation and Identification of Bacterial Endophytes from Grain Amaranth (Amaranthus caudatus) for Plant Growth Promotion

Background: Bacterial endophytes lives in internal tissues of root, stem and leaves of grain amaranth plants. Isolation and screening of efficient bacterial endophytes for plant growth promotion, biocontrol activities and drought tolerance can develop as suitable bioinoculants for alleviate drought and stress tolerance and plant growth promotion.
Methods: Bacterial endophytes were isolated from grain amaranth (Amaranthus spp) and all isolates were screened for nitrogen fixation, phosphorous solubilisation, growth hormone production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production. Molecular identification of bacterial isolates was done by 16S rRNA sequencing to identify the organisms.
Result: Seventeen isolates showed high growth in N-free media and nine isolates could efficiently solubilize phosphates. Two isolates significantly produced higher concentrations of gibberellins, maximum number of bacterial isolates produced Indole-3-acetic acid (IAA) and eight isolates were able to produce cytokinins. Fifteen isolates have shown positive for ACC activity [1-Aminocyclopropane-1-carboxylate (ACC) deaminase production] in grain amaranth and five bacterial isolates (RAR-5, RAS-3, RAL-7, WAR-1 and WAS-11) have significant plant growth promoting activities compared to others. Further, significant bacterial isolates were identified as Alcaligenes faecalis subsp. phenolicus, Pseudomonas moorei, Bacillus siamensis, Bacillus cereus and Acromobacter deleyi by 16S rRNA gene sequencing.
