Effect of Cohabiting Endophytic Fungi with Aspergillus subramanianii of Gyrinops walla on the Antibacterial Activity Against Staphylococcus aureus

Abstract

The ability to cure infectious diseases is being threatened by the emergence and global dissemination of antimicrobial resistance mechanisms. Mix culturing of fungi plays a significant role in the quest for new antimicrobial compounds and/or enhanced production of known active compound/s synthesized by either organism. Aspergillus subramanianii, an endophyte of Gyrinops walla; is known to possess antibacterial activity against Staphylococcus aureus. In the present study, out of eight endophytic fungi of G. walla cohabiting with A. subramanianii tested, only two; VEF 4 and VEF 8 showed poor antibacterial activity against S. aureus in agar plug assay. These two and another four endophytes (VEF 1, VEF 3, VEF 9, and VEF 10) of G. walla which did not show any antagonistic activity against A. subramanianii in the dual culture assay were selected and separately co-cultured with A. Subramanianii in Potato Sucrose Agar. A significant increase was observed in the zone of inhibition when the ethyl acetate fraction of 3 week–old mix culture of A. subramanianii and VEF 4, compared to that of the monocultures of each candidate. The TLC bioautogram showed a single active spot for both the crude ethyl acetate fractions of mixed culture and the axenic culture of A. subramaianii. The HPLC-UV profiles of the active spots revealed that both members produced the same compounds suggesting the increased efficiency may be due to the total effect of the two members in mixed cultures.