Abstract

Aim: The study aimed at studying, identifying, and evaluating the bioactive properties of endophytic bacteria isolated from the medicinal plant Dillenia pentagyna Roxb.
Methods: An agar well diffusion assay was employed for antimicrobial screening. 16S rRNA gene sequencing was done to identify selected bacteria. Antioxidant assays using DPPH and ABTS radical scavenging assays were performed. Cytotoxicity was tested using the MTT assay, and detection of secondary metabolites was done using HPTLC.
Results: Among the 96 isolates, one endophytic bacterium, BPSL8, identified as Bacillus pumilus, had the most significant activity. The crude methanol extract of BPSL8 exhibited antibacterial activity against Micrococcus luteus, Bacillus subtilis, and Klebsiella pneumoniae. BPSL8 has a potent antioxidant capacity of DPPH and ABTS free radicals with an IC₅₀ of 6.29 and 4.25 µg/mL, respectively. BPSL8 was found to have cytotoxicity against HT29 (IC50 55.2 µg/mL) and HeLa (IC50 51.9 µg/mL). HPTLC analysis done for three fractions (DCM, EA, and MeOH) of BPSL8 detected the presence of phytochemicals.
Conclusion: This study demonstrates the potential of the identified endophytic bacterium B. pumilus as a source of as a potent antibacterial, antioxidant, and anticancer agent with a key role in providing insights into their impact on the host as well as their applications in the field of pharmaceuticals.

Key words: Antimicrobial, Bacillus, Bioactive compounds, Endophytes, HPTLC