Continuous consolidated bioprocessing of lignocellulose to ethanol or organic acids in a multispecies biofilm membrane reactor
Wednesday, April 30, 2014: 10:10 AM
Grand Ballroom F-G, lobby level (Hilton Clearwater Beach)
Robert Shahab, Institute of Process Engineering, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland, Simone Brethauer, School for Agricultural, Forest and Food Science, Bern University of Applied Sciences, Zollikofen, Switzerland and Michael Studer, School of Agricultural, Forest and Food Sciences, Bern University of Applied Sciences, Zollikofen, Switzerland
The biochemical conversion of recalcitrant lignocellulosic biomass to desired chemicals requires complex process schemes that need to be simplified to improve economics. To this end, we developed a process, which allows the consolidated bioprocessing of lignocellulose to ethanol or organic acids in a single multi-species biofilm membrane (MBM) reactor featuring coexistent aerobic and anaerobic conditions necessary for the simultaneous fungal cellulolytic enzyme production and fermentation of the hydrolysis-derived sugars.

After demonstrating the successful production of ethanol from pretreated wheat straw in 30 mL flat sheet membrane batch reactors by the combined action of T. reesei, S. cerevisiae and S. stipites (70% yield) we scaled up the process to 500 mL. The improved reactor design allowing for state of the art process control features a tubular silicone membrane submerged in the fermentation slurry. We then set up a continuous MBM process by connecting up to four of such stirred tank reactors in series in order to characterize system stability, optimize fermentation conditions and establish achievable yields.

Furthermore, the product range of the MBM process was extended by changing the product forming microorganism. In conjunction with T. reesei, e.g. Lactobacillus delbrückii produced lactic acid and Actinobacillus succinogenes produced succinic acid based on microcrystalline cellulose and steam exploded biomass. These examples show the huge potential of the MBM-process to be applied as a universal synthesis platform for desired bio-chemicals based on lignocellulosic biomass.