The effects of different yeast extracts on secondary metabolite production in Fusarium.

Yeast extract is an important constituent in several media used for metabolite profiling of filamentous fungi. The nutrient composition can vary between brands and thereby influence production of secondary metabolites, which can be regulated in response to nitrogen, carbon and pH. In the present study we examined the production of known secondary metabolites in Fusarium pseudograminearum, Fusarium graminearum, Fusarium avenaceum and Fusarium fujikuroi and in each species we identified several secondary metabolites which are influenced by yeast extract brands. Deoxynivalenol and zearalenone were produced in high levels on some yeast extract by F. pseudograminearum and F. graminearum, while absent on others. Chlamydosporol, 2-AOD-3-ol and enniatins were influenced by yeast extracts in F. avenaceum, while bikaverin, gibberellic acid, fumonisin and fusaric acid were affected in F. fujikuroi. Aurofusarin and fusarin C on the other hand were not affected by yeast extracts in all producing strains. The observed differences in production in metabolite profiles show the need to use the same yeast extract brand in repeating experiments. The study illustrates furthermore that it can be beneficial to use more than one yeast extract in metabolite profiling a species.