Pre-treatment and fermentation of biobased feedstocks

Projecttitel: Developing, optimization & validation of cellulosome based consolidated bioprocesses for pre-treatment and fermentation of biobased feedstocks
Projectnummer: BBE-1711
Looptijd: 2018 – 2021
Budget publiek: € 502.000
Budget privaat: € 171.000
Projectleider: Paulien Harmsen
Betrokken partijen: Biodetection Systems, MicroLife Solutions, Wageningen University & Research

The aim of the BIOCONSOLE project is to further develop and optimize microbial based solutions for biomass pretreatment and fermentation and combine active enzymes discovered in previous and current TKI projects such as BIOCOM, into custom cellulosome based enzyme complexes for consolidated bioprocesses to increase depolymerization and conversion rates. Cellulosomes are enzyme complexes comprised of multiple types of cellulose degrading enzymes bound to scaffolding proteins which contain carbohydrate binding domains to bring the enzymes into close proximity to the cellulose substrate and increase hydrolyzation activity. Cellulosome protein content can be customized to optimize cellulase activity and to add functionality. By engineering active enzymes discovered in other TKI projects, we can assemble custom cellulosomes to simultaneously breakdown lignocellulose and remove fermentation inhibitors with the aim to minimally double the hydrolyzation speed end yields over conventional pretreatment and saccharification levels. Conventional pretreatment and fermentation approaches use harsh physical and chemical methods which are energy demanding, environmentally unfriendly and generate compounds that inhibit downstream fermentation.

After fermentation, cellulolytic enzymes are used to depolymerize cellulose which is followed by fermentation to convert sugar into end products such as ethanol. By combining mild pretreatment with cellulosomic based depolymerization and fermentation inhibitor removal steps, several drawbacks such as low enzyme activity and microbial sugar consumption can be circumvented. In TKI inzet 2014-2015 (BIOCOM) industrially relevant sources and extreme ecosystems are being explored to find microbes and develop enzyme cocktails to efficiently break down biomass in order to investigate which combinations of microbes or enzymes can assist in mild pretreatment methods, efficiently break down lignocellulose and remove fermentation inhibitors. In TKI inzet 2016 optimal combinations of enzymes will be further validated and combined into cellulosome complexes to be used in integrated, consolidated bioprocesses. Mild biomass pretreatment will keep cellulose and lignin fractions intact after which both fractions can be separated and individually converted to desirable endproducts. For the conversion step cellulosome based enzyme complexes will be used for depolymerization and removal of unwanted molecules which can be combined with fermentation by microbes for simultaneous saccharification and conversion. To better assess conversion efficiency, we will further develop and validate monitoring systems in the form of cell based reporter assays to monitor the generation of inhibitory compounds and compounds that may infer toxicity to both the process as well as end products. The generation of these adverse compounds may be biomass specific and by monitoring this process combinations of enzymes can be rapidly deployed to specifically remove inhibitors generated in specific types of biomass. Overall aim and results of this project and inzet projects are expected to significantly improve our capacity to efficiently convert novel and conventional streams of feedstock into biofuels and biochemicals.