Muscodor sp. IBRL OS-94, A Promising Endophytic Fungus of Ocimum sanctum with Antimicrobial Activity

Abstract

Background: An endophytic fungus, Muscodor sp. IBRL OS-94 isolated from the leaf of Ocimum sanctum was believed to possess significant antimicrobial activity and several assays were carried out to evaluate its pharmaceutical potential. Methods: Agar plug diffusion and the disk diffusion assays were performed to evaluate the antimicrobial activity of the fungal extract. Also, the broth microdilution assay was done to investigate the minimum inhibitory concentration (MIC) of the fungal extract. Meanwhile, the scanning electron microscope (SEM) was employed to observe the structural degeneration of the microbial cells treated to the extract. Results: The results revealed that fungal isolate showed favorable antimicrobial activity through agar plug diffusion assay and the disk diffusion assay demonstrated that most of the test microorganisms were susceptible to extracellular extract compared to extracellular extract. As for the MIC and MLC values, the extracellular fungal extract exerted a bactericidal/fungicidal effect against all five Gram-positive bacteria, four Gram-negative bacteria, one yeast, and none of the test fungi. Meanwhile, the intracellular fungal extract exhibited bactericidal/fungicidal activity against three Gram-positive bacteria, one Gram-negative bacterium, and one yeast. The structural degeneration study via SEM revealed that various cell abnormalities including severe damage to the cell wall which led to microbial cell death. Conclusion: The present study suggests the fungal extract from Muscodor sp. IBRLOS-94 as an antimicrobial agent.

Bioactivity of Clitoria ternatea Crude Extracts Against Pathogenic Bacteria

“…The current investigation also showed that the diameter of the inhibition zone was considerably larger in the good diffusion assay (Table 2) than in the disc diffusion assay. This finding was consistent with Jalil et al (2021) who claimed that agar plug diffusion and disc diffusion assays produced differing results for various test microorganisms' susceptibility to an extract. This phenomenon may be influenced by the concentration of bioactive substances, the depth of the agar medium, and the diffusion rate.…”

“…Besides that, the aqueous extract may exert a bacteriostatic effect against P. aeruginosa and K. pneumoniae since the percentage of bacterial reduction was in the range of 79.75% and 82.21%, respectively. A previous study by Jalil et al (2021) on time-killing revealed this pattern and they concluded that the efficacy of the extract is dependent on dose and exposure time. Similar findings were made by Saeloh and Visutthi (2021), who found that the reference strains of S. aureus ATCC29213, Methicillin-resistant S. aureus NPRC001R, and E. coli ATCC25922 were all susceptible to the antimicrobial effects of Piper betle extract.…”