Exploration of Antifungal Metabolites of Aspergillus terreus (ENF12), an Endophytic Fungus Isolated from Mulberry (Morus indica L.) Leaf

Aims: The aim of this study was to explore the metabolic profile of endophytic fungi, Aspergillus terreus (ENF12) isolated from mulberry leaf and evaluate their antifungal efficacy against Macrophomina phaseolina causing charcoal rot disease of mulberry.

Study Design: Completely Randomized Block Design.

Place and Duration of Study: Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu during August 2018 to June 2019.

Methodology: The isolation was done by serial dilution and plating method. The culture was identified by utilizing the morphological, microscopical and taxonomical keys as A. terreus. The macroscopic observations such as colony growth, color, texture, pigmentation, growth rate and microscopic observations viz. hyphal and conidial characters were studied. The molecular confirmation was done by DNA sequencing using ITS 1 and ITS 4 primers. The extracellular secondary metabolites were extracted from A. terreus and screened against M. phaseolina by agar well method. The composition of the metabolites was analyzed through GC-MS.

Results: The septate and hyaline mycelium along with aleurioconidia was observed under microscope and based on the DNA sequencing, the ENF12 isolate was identified as A. terreus. The major compounds identified from the extracellular metabolites of A. terreus were tromethamine, benzenediol, tetracosamethyl cyclododecasiloxane, hexadecanoic acid, benzoic acid and pregnatriene. The ethyl acetate extract of the metabolite at 4000 ppm suppressed the growth of M. phaseolina by 77.78%. The pathway analysis revealed that the metabolites are involved in the metabolism of drug development, cellular processes, organismal systems and other pathways. The major identified metabolites and pathways were grouped under biosynthesis of other secondary metabolites, lipid metabolism and energy metabolism.

Conclusion: The endophytic fungi, A. terreus from mulberry could be an effective antifungal agent against M. phaseolina. The metabolic pathway analysis found that the major metabolites identified from A. terreus were also reported in mulberry plants thereby showed the mutual interaction between the host and endophyte.