Current status and future perspectives on fungal solid-state fermentation scale-up

Solid-state fermentation and, particularly, fungal bioprocesses, face relevant scale-up challenges. Motivated by the immense potential of fungal solid-state fermentation in the context of the circular bioeconomy, this review studies fungal solid-state fermentation scale-up, analysing the current status and perspectives of the main reactor configurations used: bags, trays, packed-beds and rotatory drums. It shows that most studies reach technology readiness level 4 but few have gone further due to the necessity of a relevant industrial environment. Challenges corresponding to each configuration are summarized and discussed, including heat generation (main bottleneck when scaling most bioprocesses), productivity rise, the use of complex substrates and the integration into the modern biorefinery concept. It also offers an up-to-date revision of the most recent patents involved in fungal solid-state fermentation scale-up, providing an accurate picture of the current status of the industrial sector and highlighting a tendency for packed-bed and tray bioreactor related patents, with emphasize on modelling to overcome heat generation. Finally, it concludes that, despite substantial efforts performed during the last decade, collaboration between research and industry will be mandatory to further scale fungal solid-state fermentation up to industrial volumes, ensuring its role into the modern biorefinery concept.