An antimicrobial peptide from endophytic Fusarium tricinctum of Rhododendron tomentosum Harmaja

Abstract

Endophytic microbes have attracted considerable attention as a completely new source of pharmaceuticals in recent years. An endophytic Fusarium tricinctum was isolated from Rhododendron tomentosum, a shrub that is found widely across the northern hemisphere. The endophytic F. tricinctum produced antimicrobial compounds that were active against Staphylococcus carnosus, Candida albicans and C. utilis. The transcriptome of the F. tricinctum was sequenced, and a total of 12,006 contigs were assembled, having an N50 value of 1390 bp. Analysis of the transcriptomic PD library of F. tricinctum yielded an antimicrobial peptide named Trtesin. The expression of Trtesin transcripts was >1000 fold in the mRNA library originating from PDB-grown fungi exhibiting high antimicrobial activity compared to FG4-grown fungi with no antimicrobial activity. Trtesin was cloned, expressed, and purified in pET32(a), and it consisted of 52 amino acids with 6 cysteine molecules. The molecular weight of Trtesin is 6138.92 Da. An additional N-terminal sequencing was done to confirm the intact peptide, as well as to check the correct amino acid sequence. The MIC of Trtesin was determined against several bacteria as 64 μg/mL, and peptide showed a mild activity against F. oxysporum in agar diffusion assay, as a zone of inhibition of 10 mm was formed at 100 μg of peptide.