In vitro antibacterial activity of endophytic fungus Aspergillus flavus IBRL-C8 from Senna siamea against Gram-bacteria

Abstract

Aims: To evaluate the antibacterial efficacy of ethyl acetate extract of Aspergillus flavus IBRL-C8 against Gram-positive and Gram-negative bacteria. Methodology and results: In this experiment, an endophytic fungus which identified as A. flavus IBRL-C8 was extracted using ethyl acetate and methanol, from Senna siamea, prior to in vitro antibacterial test on eight Grambacteria. The results were significantly more enunciated to the ethyl acetate extract since the Gram-bacteria signified 9.0 to 20.0 mm of inhibition zones on Muller Hinton Agar (MHA) during disc diffusion assay. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extract were ranged from 125-1000 µg/mL and 125-2000 µg/mL, respectively. Time-kill assay depicted the ethyl acetate extract of A. flavus IBRL-C8 exceptionally retarded methicillin-resistant Staphylococcus aureus (MRSA) and also manifested extended antibacterial activity. The maximum reduction in cell numbers occurred at 2MIC concentration (250 µg/mL) during the interval time of 16 h. The malformations noticed from microscopic observations where the transformation of structural annihilation from regular spherical morphology to non-spherical shape with an irregular surface and also disruption around the cell membrane when the MRSA treated with ethyl acetate extract of A. flavus IBRL-C8. Conclusion, significance and impact of study: This study proposed the ethyl acetate extract of A. flavus IBRL-C8 as a potential antibacterial agent against MRSA infection, which can be useful in pharmaceutical application.