Applied Microbiology and Biotechnology, Vol.104, No.9, 3835-3846, 2020
Genome-based mining of new antimicrobial meroterpenoids from the phytopathogenic fungus Bipolaris sorokiniana strain 11134
Polyketide-terpenoid hybrid compounds are one of the largest families of meroterpenoids, with great potential for drug development for resistant pathogens. Genome sequence analysis of secondary metabolite gene clusters of a phytopathogenic fungus, Bipolaris sorokiniana 11134, revealed a type I polyketide gene cluster, consisting of highly reducing polyketide synthase, non-reducing polyketide synthase, and adjacent prenyltransferase. MS- and UV-guided isolations led to the isolation of ten meroterpenoids, including two new compounds: 19-dehydroxyl-3-epi-arthripenoid A (1) and 12-keto-cochlioquinone A (2). The structures of 1-10 were elucidated by the analysis of NMR and high-resolution electrospray ionization mass spectroscopy data. Compounds 5-8 and 10 showed moderate activity against common Staphylococcus aureus and methicillin-resistant S. aureus, with minimum inhibitory concentration (MIC) values of 12.5-100 mu g/mL. Compound 5 also exhibited activity against four clinical resistant S. aureus strains and synergistic antifungal activity against Candida albicans with MIC values of 12.5-25 mu g/mL. The biosynthetic gene cluster of the isolated compounds and their putative biosynthetic pathway are also proposed.
Keywords:Meroterpenoids;Phytopathogenic fungus;Bipolaris sorokiniana;Genome-based mining;Antimicrobial activity