Screening, isolation, biochemical and plant growth promoting characterization of endophytic bacteria.

Abstract

Microbially unexplored medicinal plants can have a genetically diverse microbial population with multi-functional plant growth promoting traits. Altogether, 75 endophytic bacterial strains were isolated from Withania coagulans Dunal and Olea ferruginea Royal, medicinal plants of Karak, Pakistan. Isolated endophytic bacterial strains were grouped into 8 clusters while, 4 remained ungroup on the basis of the SDS-PAGE profile of whole cell protein. Clusters representative bacterial strains were evaluated for different activities, among them 4 strains were selected for 16s rDNA gene sequencing due to their prominent results. The 16s rDNA gene sequencing homology of the representative strain WC2, WC58, WC138 and OFR115 were assigned to Enterobacter cloacae, Enterobacter dissolvens, Enterobacter hormaechei and Cronobacter Sakazakii respectively. Phylogenetic tree indicated evolutionary relationship of these bacteria to their closely related species. All of the representative bacterial isolates were screened for biochemical characteristics, and various plant growth promoting activities like phosphate solubilization, ammonia production, and indole-3- acetic acid (IAA). Indirect plant growth promoting traits, such as hydrogen cyanide production, protease production, salt tolerant capability and antagonistic activities against plant pathogenic fungi under in vitro conditions were also evaluated. These isolates were also characterized biochemically. Furthermore, the isolation of endophytic bacteria from Withania coagulans and Olea ferruginea is novel in association to these plants. Owing to these characters, the representative isolated bacteria are suggested to be used in bio-fertilizer and bio-pesticides.