Isolation and Characterization of Endophytic Fungi from Passiflora edulis, Mercurialis annua and Pouteria campechiana Using MALDI-TOF and Evaluation of Antimicrobial Efficacy of Leaf Extracts

Abstract

Aim: The present study aimed to isolate and identify the endophytic microflora of Passiflora edulis, Pouteria campechiana and Mercurialis annua plant leaves and to evaluate antimicrobial activity of their leaf extracts against pathogenic bacterial and Candida strains. Background: Endophytes have extensive uses in agriculture and medicine and provide a host with various unknown advantages in addition to producing hormones that support plant growth and help the host resist abiotic stress. In addition, bioactive secondary metabolites are produced by endophytic fungi, some of which come from the host plants. Methodology: The healthy plant leaves were subjected to surface sterilization. The leaf segments were cut aseptically (1cm x 1cm) and placed in Petri dishes containing Potato Dextrose Agar (PDA) and incubated at room temperature for 7 days. Identification was done based on macroscopic, microscopic characteristics and MALDI-TOF Analysis. Ethanolic leaf extracts were prepared and the antimicrobial activity of three plants were evaluated by using Disc diffusion and Agar well diffusion method. Results: A total of 40 endophytic fungi were isolated from healthy leaves such as, Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Talaromyces spp, Fusarium solani, Mucor spp, Rhizopus spp and Candida albicans. The overall colonization rate of endophyte in all the 3 leaf segments was found to be 74.07%. The extracts of P. edulis, P. campechiana and M. annua exhibited considerable effectiveness in the agar well diffusion method compared to the disc diffusion method. P. campechiana leaf extracts exhibited significant antimicrobial activity against all the tested organisms such as Escherichia coli, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Staphylococcus aureus and Candida spp. Conclusion: This study highlights the diversity of endophytic fungal communities inhabiting P. edulis, P. campechiana and M. annua, as well as the antimicrobial property of ethanolic leaf extracts.  These findings imply the potential of endophytic fungi as a source of bioactive compounds and the effectiveness of plant extracts in antimicrobial applications.