Design of Fungal Co-Cultivation Based on Comparative Metabolomics and Bioactivity for Discovery of Marine Fungal Agrochemicals.

Microbial co-cultivation is employed for awakening silent biosynthetic gene clusters (BGCs) to enhance chemical diversity. However, the selection of appropriate partners for co-cultivation remains a challenge. Furthermore, competitive interactions involving the suppression of BGCs or upregulation of known, functional metabolite(s) during co-cultivation efforts is also common. Herein, we performed an alternative approach for targeted selection of the best co-cultivation pair. Eight marine sediment-derived fungi were classified as strong or weak, based on their anti-phytopathogenic potency. The fungi were co-cultured systematically and analyzed for their chemical profiles and anti-phytopathogenic activity. Based on enhanced bioactivity and a significantly different metabolite profile including the appearance of a co-culture specific cluster, the co-culture of (strong) and (weak) was prioritized for chemical investigation. Large-scale co-cultivation resulted in isolation of five polyketide type compounds: two 12-membered macrolides, dendrodolide E () and its new analog dendrodolide N (), as well as two rare azaphilones spiciferinone () and its new analog 8a-hydroxy-spiciferinone (). A well-known -naphtho-γ-pyrone type mycotoxin, cephalochromin (), whose production was specifically enhanced in the co-culture, was also isolated. Chemical structures of compounds - were elucidated by NMR, HRMS and [] analyses. Compound showed the strongest anti-phytopathogenic activity against and with IC values of 0.9 and 1.7 µg/mL, respectively.