BIOLOGICAL ACTIVITIES AND BIOACTIVE COMPOUNDS OF ENDOPHYTIC BACTERIA FROM <i>Ocimum gratissimum</i> (<i>Scent leaf</i>)

Abstract

Endophytic bacteria are beneficial microorganisms residing within plant tissues, often producing bioactive compounds with therapeutic potential. Ocimum gratissimum, a medicinal plant, is known to host diverse endophytic bacteria. This study investigated the biological activities of metabolites produced by endophytes isolated from O. gratissimum using the imprinting method. The isolates were characterized based on cultural and molecular identification. Antibacterial activity of the crude metabolites was assessed against clinical isolates using the agar well diffusion method, while antioxidant potential was evaluated using standard procedure. Gas Chromatography–Mass Spectrometry (GC-MS) analysis of crude metabolites was done to identify bioactive compounds. Identified bacterial strains included Bacillus siamensis, Bacillus cereus, Pseudomonas aeruginosa, Pseudomonas putida, Bacillus subtilis, Pseudomonas fluorescens, and Enterobacter aerogens. Pseudomonas aeruginosa exhibited the highest antibacterial activity, and exhibited concentration-dependent inhibitory effects, with maximum zones of inhibition reaching 12.66 ± 0.33 mm at 100% and 0.00±0.00 mm at 12.5% concentration. Antioxidant Properties of Crude Metabolites of P. aeruginosa was determined using Vitamin C control, the result indicated that the metabolite had very minimal activity (<100%) when compared to the control. Crude metabloites from P. aeruginosa revealed the presence of bioactive compounds such as 4(1H)-Isobenzofuranone, hydrocinnamic acid, and 2-hydroxy-3,5,5-trimethyl-cyclohex-2-enone compounds known for their antioxidant properties. These findings highlight the potential of endophytic bacteria from O. gratissimum as promising sources of natural bioactive agents for pharmaceutical and therapeutic applications.