Isolation and identification of endophytic bacteria with plant growth promoting and biocontrol potential from oak trees

Abstract

SummarySamples of roots, leaves and stems of healthy oak trees were collected from various locations in the Baneh and Marivan regions, Iran. In total, 63 endophytic bacteria were isolated and grouped according to phenotypic properties. Seven selected isolates were further identified by partial sequencing of the 16S rRNA gene. Isolates Pp54, Pp88, Pp95 and Pp177 were Pseudomonas spp., isolates Sm59 and Sm79 were Stenotrophomonas spp., and isolate Bf 172 was a Bacillus sp. The ability of these isolates for plant hormone production such as auxin and gibberellin was evaluated, along with siderophore production, phosphate solubilization, atmospheric nitrogen fixation, protease and hydrogen cyanide production. All strains produced auxin and gibberellin in different amounts. Atmospheric nitrogen fixation ability was positive for strains Sm79, Pp54, Pp88 and Pp95. All strains except Sm79 solubilized phosphate. Strains Sm59, SM79, Pp88, Pp177 and Bf172 produced protease. Pp88, Pp95, Bf172 and Pp177 were able to produce siderophore. Strains Sm79 and Pp95 released low concentrations of hydrogen cyanide. Amongst the strains tested, Pp95, Pp88, Pp177 and Sm79 had different inhibitory effects on the bacterial plant pathogen, Pseudomonas syringae pv. syringae under in vitro conditions. This is the first reported case of endophytic Bacillus, Pseudomonas and Stenotrophomonas strains from oak trees in Iran.