Towards industrial application of fungal pretreatment in 2G biorefinery: scale-up of solid-state fermentation of wheat straw

Fungal pretreatment of lignocellulosic biomass for bioethanol production is an environmental-friendly alternative to steam explosion. However, this biological pretreatment has been tested on a small scale, where most of the typical problems of solid-state fermentations (SSF), such as limited aeration or temperature control, are not observed. The main objective of this study was to assess the feasibility of the fungal pretreatment of lignocellulosic biomass (wheat straw) at a demonstration scale using the white-rot fungus Irpex lacteus to improve straw digestibility. Different configurations were evaluated for the design of a 22 L SSF reactor, but a versatile vertical design that can operate as a packed-bed and as a tray reactor was selected. The wheat straw digestibility obtained in the SSF bioreactor after 21 days of pretreatment (60.6%) was similar to that achieved on a small scale (57.9%). In addition, the most common online monitoring variables (temperature and CO2 production) correlate with the fungal action on wheat straw. As well as the weight loss, obtaining comparable results at flask and reactor scale (30 and 34.5%, respectively)Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This research was funded by the Spanish Ministry of Science and Innovation: Demo E2 project (PEN-120000–2009-31), as part of the National Plan of Scientific Research, Development and Technological Innovation, related to the Special Fund of the Government for enhancing the Economy and Employment, Plan E (Local investment fund for the Employment, Government of Spain), WooBAdh project (PCI2018-092866, ERA-CoBioTech program), and BioFlav-OH project (RTI2018-094482-J-I00). S.G. and G.E. received financial support from the Spanish Ministry of Science, Innovation and Universities (Grant references BES-2017–081677 and RYC2018-024846-I)S