Antibacterial activity of crude extract from Aspergillus niger isolated from the stilt roots of Rhizophora apiculata along South Andaman coast, India

Abstract

Endophytic fungi are known repositories of secondary metabolites. They also serve as protectors and growth enhancers to their respective plant hosts. The present study was aimed at studying the antibacterial activity of the extract of endophytic fungus Aspergillus niger isolated from the stilt roots of Rhizophora apiculata. The ethyl acetate extract of the fungus species was assayed for bioactivity against five human pathogenic bacterial strains Staphylococcus aureus (MTCC96), Micrococcus luteus (MTCC106), Pseudomonas aeruginosa (MTCC326) and Enterococcus faecalis (MTCC439), Proteus mirabilis (MTCC1429) by disc diffusion method. Sensitivity of the strains varied from P. mirabilis, which was most sensitive followed by P. aeruginosa, M. leuteus, S. aureus and E. faecalis in order. It suggested that both gram positive and negative bacterial strains responded to the effect of crude extract exhibiting the activity zone with a range of 23mm to 15mm at 50µl and 100µl concentrations respectively. Phytochemical analysis of the crude extract revealed the presence of terpenoids, saponins and proteins, suggesting that these biomolecules have potential to serve as antibacterial compounds.