Endophytic Fungi from Emblica urinaria as Emerging Sources to Target Multidrug-Resistant Bacterial and Fungal Pathogens

Antimicrobial resistance has become a major global health concern. In this context, the present study aimed to explore endophytic microorganisms from Emblica urinaria as a potential source of antimicrobial metabolites. E. urinaria samples were collected and identified based prior to the isolation of endophytes. The endophytes were then isolated and assessed in terms of their antimicrobial activity against different pathogen strains, including Gram-positive (MRSA_Methicillin-resistant Staphylococcus aureus, Bacillus subtilis, and Streptococcusfaecalis), Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Klebisiella pneumoniae) strains, and Candida albicans, using agar plug method. The endophytes with detectable antimicrobial activity were identified using morphological and molecular methods (Internal Transcribed Spacer sequencing_ITS). Afterwards, the culture conditions of the most potential strain were optimized, using one factor at a time, and Response surface methodology. Eventually, its major bioactive compounds was preliminarily screened using LC-MS-MS method. The results showed that a total of eleven endophytes strains were isolated from E. urinaria. Four of the eleven strains demonstrated promising antimicrobial activity against both Gram-positive and Gram-negative strains. Especially, an antifungal activity against C. albicans was detected for the first time in E. urinaria endophytes. These endophytes were identified to be Colletotrichum aeschynomenes (CD-R1), Diaporthe etinsideae (CD-T1), Phyllosticta fallopiae (CD-R4), and Albifimbria viridis (CD-L1). The CD-L1 (Albifimbria viridis) was the strain with the most relevant antimicrobial activities. Its opitmal culture conditions was determined to be Potato Dextrose Broth (PDB), with five days of incubation, under agitation, at an intial inoculum size of 105 spores/mL, pH 6, and with sucrose (32.5 g/L) and potato extract (200 g/L) as carbon and nitrogen source, respectively. In terms of its metabolites’ chemical compotision, LC–MS/MS profiling detected seven metabolite features putatively annotated as verrucarin-, roridin-, and trichoverrin-type trichothecene derivatives. This study was the first study that focus on the antimicrobial potential of E. urinaria endophytes and reconfirmed the important role of endophytes metabolites as an abundant source for antimicrobial agents.