Screening of plant growth-promoting endophytic bacteria from the roots of the medicinal plant Aloe vera

Abstract This work aimed to test the hypothesis that the root bacteria of Aloe vera (Asphodelaceae) present multifunctionality with potential in biotechnology for plant growth. A total of 129 endophytic bacteria from three environments, a field, a garden, and nursery were isolated and evaluated for indole-3-acetic acid-producing ability. Thirty-two of the total bacteria isolates were evaluated for siderophore production, phosphate solubilization and antibiosis to phytopathogenic fungi. The phylogenetic analysis revealed the presence of four groups: Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria. The functional trait for indole-3-acetic acid (IAA) synthesis was observed in 32 of the isolates, with emphasis on the 135 V Enterobacter tabaci strain, which revealed the highest production (225.2 μg mL−1). The results found for Bayovar phosphate solubilization were not expressive, with the highest values observed for the bacterium 149H Paraburkholderia sp. (45.7 mg L−1). The 3 V isolate Brevibacillus agri presented 45.6% antagonism against Sclerotinia sclerotiorum. The greatest inhibition of the phytopathogens Fusarium sp. and Rhizoctonia sp. was observed with 149H Paraburkholderia sp. and 348 V E. tabaci, respectively. Studies evaluating to evaluate the potential of endophytic bacteria of A. vera for plant growth promotion are rare and our results indicate that the isolates 135 V and 348 V E. tabaci and 149H Paraburkholderia sp. have potential for to be field-tested as growth promoter inoculants.