Tuesday, April 30, 2013
Exhibit Hall
Solid-state fermentation (SSF) has attracted a lot of industrial interest since the formation of aerial hyphae induced by this cultivation mode promotes the production and excretion of a lot of valuable metabolites. However, SSF suffers from technological limitations, such as the control of humidity, temperature and pH inducing a several technical issues during the scaling-up procedures. This study is focused on the design of a biofilm reactor comprising a metal structured packing for fungal fermentation combining the technical advantages of submerged fermentation (Smf) with the microbial physiology related to Solid-State Fermentation (SSF). High-energy X-ray tomography has allowed us to determine the best bioreactors operating conditions leading to the best fungal colonization of the metal packing. The organism used in this work is Aspergillus oryzae carrying a glaB::gfp translational reporter. The glaB promoter is induced specifically in SSF conditions and can thus be used as a physiological reporter of the conditions encountered in biofilm reactor. Several fermentation runs have been carried out either in submerged reactor or in the biofilm reactor in order to determine the excretion efficiency of the glaB::GFP. We have shown that the biofilm reactor allows the enhancement of glaB::GFP excretion in some operating conditions suggesting that the SSF-like physiology can be encountered in this particular bioreactor configuration.