Isolation and characterization of endophytic bacteria from Panax vietnamensis Ha et Grushv.

This study aimed to isolate and characterize endophytic bacteria from Panax vietnamensis Ha et Grushv., a rare medicinal ginseng species endemic to Vietnam. Several bacterial strains were isolated from root, stem, and leaf tissues, among which strain HS10, identified as Burkholderia sp., exhibited notable plant growth-promoting traits including indole-3-acetic acid (IAA) production, proteinase activity, and strong growth. Phylogenetic analysis based on 16S rRNA gene sequences confirmed the taxonomic placement of HS10 within the Burkholderia genus. IAA production was evaluated over a 5-day period with varying concentrations of L-tryptophan, revealing optimal production (46.61±5 µg/mL) on the fourth day at 0.1–0.15% tryptophan. Additionally, antibiotic susceptibility testing showed that HS10 was highly sensitive to cefadroxil and tetracycline, while resistant to cefpodoxime. These findings contribute to the understanding of the microbial diversity associated with P. vietnamensis and support the potential application of endophytic Burkholderia strains as biofertilizers to enhance sustainable ginseng cultivation medium.