Genomic and Metabolomic Analysis of the Endophytic Fungus S6 Isolated from : Identification of Anti-Bacterial Properties and Production of Succinic Acid.

Endophytic fungi are prolific sources of bioactive metabolites with potential in pharmaceutical and biotechnological applications. Here, the endophytic fungus, S6, was isolated from (speedwell), and conducted its anti-microbial activities, whole-genome sequencing and metabolome analysis. The ethyl acetate extract of this fungus exhibited strong anti-bacterial activity and the inhibition zones, induced by the fungal extract at 20 mg/mL, reached 16.25 ± 0.5 mm and 26.5 ± 0.5 mm against Gram-positive and Gram-negative bacteria. To unravel the biosynthetic potential for anti-bacterial compounds, whole-genome sequencing was conducted on S6, resulting in a high-quality assembly of 42.93 Mb encoding 13,885 protein-coding genes. Comprehensive functional genome annotation analyses, including gene ontology (GO) terms, clusters of orthologous groups (COGs), Kyoto encyclopedia of genes and genomes (KEGG), carbohydrate-active enzymes (CAZymes), and antibiotics and secondary metabolites analysis shell (antiSMASH) analyses, were performed. According to the antiSMASH analysis, 58 biosynthetic gene clusters (BGCs), including 16 non-ribosomal peptide synthetases (NRPSs), 21 terpene synthases, 12 polyketide synthetases (PKSs), and 9 hybrids, were identified. In addition, succinic acid was identified as the major metabolite within the fungal extract, while 20 minor bioactive compounds were identified through LC-MS/MS-based molecular networking on a GNPS database. These findings support the biotechnological potential of S6 as an alternative producer of succinic acid, as well as novel anti-bacterial agents.