Molecular identification of endophytic fungi from known herbal plants and effect of co-cultivation on the fungi bgcs using gc-ms as a tool

Abstract

The increasing prevalence of antimicrobial resistance has necessitated the search for novel bioactive compounds from alternative natural sources. Endophytic fungi are recognized as prolific producers of structurally diverse secondary metabolites, many of which possess significant pharmaceutical potentials. This study investigated the effects of co-cultivation on secondary metabolite production by endophytic fungi isolated from the medicinal plants Bryophyllum pinnatum and Sansevieria trifasciata. The objective was to evaluate whether co-culture could stimulate metabolic diversification through activation of silent biosynthetic gene clusters (BGCs) compared with monoculture fermentation. Endophytic fungi were isolated from healthy leaf tissues, purified, and identified using internal transcribed spacer (ITS) region sequencing and BLAST analysis. The isolates were identified as Penicillium oxalicum (BP1), Diaporthe sp. (BP8), Curvularia chiangmaiensis (BP5), and Curvularia lunata (ST1). Pure cultures and co-cultures (BP1+BP8 and ST1+BP5) were fermented on rice-based solid-state media for 21 days, and metabolites were extracted with ethyl acetate. Gas chromatography–mass spectrometry (GC–MS) analysis revealed metabolite profiles dominated by fatty acids, fatty acid esters, and terpenoid derivatives. Monoculture extracts showed prominent peaks corresponding to hexadecenoic acid, linoleic acid, oleic acid, and related esters, while BP5 exhibited a more complex profile containing terpenoid compounds such as squalene. Comparative chromatographic analysis demonstrated that the BP1+BP8 co-culture maintained a metabolite profile similar to those of the parent strains, indicating an additive interaction with minimal metabolic disruption. In contrast, the ST1+BP5 co-culture displayed substantial alterations in metabolite distribution, characterized by increased volatile compounds and reduced fatty acid dominance, suggesting metabolic reprogramming and activation of previously silent biosynthetic pathways. These findings demonstrate that fungal co-cultivation can significantly influence secondary metabolism, although the outcome depends on the interacting species. The study highlights co-culture as a valuable strategy for enhancing chemical diversity and facilitating the discovery of novel natural products with potential pharmaceutical applications.