The Thai Journal of Pharmaceutical Sciences
Abstract
Background: A foodborne bacterium, Bacillus cereus is one of the common food contaminants that could cause food poising with several sickness symptoms to humans. Objective: This study was undertaken to evaluate the effect of ethyl acetate extract of endophytic fungus, Lasiodiplodia pseudotheobromae Industrial Biotechnology Research Laboratory (IBRL) OS-64 towards a test bacterium, B. cereus with emphasis on bacterial growth reduction and cell morphological changes. Materials and Methods: The ethyl acetate (fermentative broth) and methanolic (fungal biomass) extracts were screened for their antibacterial activity against test bacteria via agar disc diffusion assay. Results: The results demonstrated that there is a significant antibacterial activity of the ethyl acetate extract with a diameter zone of inhibition in the value of 22.0 ± 0.6 mm. However, no antibacterial activity was observed from the methanolic extract. In broth microdilution assay, the minimum inhibitory concentration and minimum bactericidal concentration values of the extract were 250 and 500 μg/mL, respectively. The results revealed that the extract exhibited a bactericidal effect on the test bacterium. A time-kill study was then performed to determine the efficacy of the extract and the results showed that the antibacterial activity of the extract was dose and time-dependent. The morphological changes of the bacterial cells exposed to the extract were observed under a scanning electron microscope and transmission electron microscope. The results revealed the abnormalities of the treated bacterial cells compared to the control and thus led to ultimate death beyond repair. Conclusion: The present study suggested the potency of the ethyl acetate extract from an endophytic fungus, L. pseudotheobromae IBRL OS-64 could be further used as an antibacterial agent.
Publisher
Faculty of Pharmaceutical Sciences, Chulalongkorn University
First Page
545
Last Page
551
Recommended Citation
Jalil, Mohd Taufiq Mat and Ibrahim, Darah
(2021)
"Effect ethyl acetate extract ofLasiodiplodia pseudotheobromae
Industrial Biotechnology Research Laboratory OS-64 on growth and cell morphology of a foodborne bacterium,Bacillus cereus,"
The Thai Journal of Pharmaceutical Sciences: Vol. 45:
Iss.
6, Article 13.
Available at:
https://digital.car.chula.ac.th/tjps/vol45/iss6/13