Analysis of Fusarium secondary metabolites through OSMAC strategy

Abstract

[EN] Fungal secondary metabolites (SMs) have been brought to the spotlight due to their numerous promising properties in different fields of the industry, and therefore the research focused on the discovery of novel compounds has considerably increased through the last decades. However, the challenge does not only rely on discovering the SMs, but also on optimizing their production, and to do so, it is essential to link them to their respective biosynthetic gene clusters (BGCs). The expression of PKS35 in Fusarium solani is still under study as it seems to be a complicated BGC to trigger due to its inactivity in usual growth conditions. To overcome this issue, the present study aimed to study the production of PKS35 compounds through an OSMAC strategy and several genetically engineered mutants from both F. solani and F. graminearum. Through phenotypical and metabolical resulting data obtained in this study, it has been possible to draw conclusions regarding the activity of PKS35 in several media and conditions, pointing to rice agar, YES, and PDA as optimum growth media for the study of this BGC, and 3 candidate compounds are proposed. Additionally, UV light seemed to trigger the expression of PKS35 and it was further linked to perithecia pigmentation in F. solani. Still, there were some factors that complicated the study of PKS35’s production rates, such as the connected regulation with PKS3 and the observed interaction with PKS12, since a high rate of one of the pathways’ intermediates rubrofusarin was yielded when PKS35 was found active in F. graminearum mutants.