Cutting-edge technologies and strategies have been developed for each stage of the BIOCON-CO2 platform that can be combined as “puzzle pieces” depending on the target chemical and the used biological system.
• Creation of a database of gas composition. The CO2-producing industrial partners (iron&steel, cement and electric power industries) have analysed and integrated statistics of gaseous effluents from different gas streams. This database has guided the research performed on WP3 to WP5 to develop robust MCFs able to use real gases with any or minimum pre-treatments as raw materials.
• CO2 solubilisation technologies. An array of technologies/strategies for increasing CO2 solubility, applicable to the different types of microorganisms and enzymes have been developed. This includes: a fixed trickle bed reactor with advanced materials, gas fermentation systems such as AnaRAMOS and glasshaker, pressure fermentation and an engineered carbonic anhydrase enzyme with improved performances.
• Bioprocess development. During BIOCON-CO2 four microbial cell factories (MCFs) had been developed using anaerobic microorganisms (Clostridium spp. for C3-C6 alcohols), aerobic microorganisms (Cupriavidus necator for PHAs) and enzymes (formate dehydrogenase for formic acid and multienzymatic system for lactic acid production), thus proving high flexibility and versatility to the BIOCON-CO2 platform. In each MCF different strategies to increase tolerance to impurities and to enhance their productivity applying genetic improvement tools have been investigated.
• Downstream processes: The main goal of the BIOCON-CO2 approach for the downstream processes is to create an integrated process for extracting and purifying the different building blocks based on their differential properties of the products compared to those of the media they are in. An automated tailored statistical tool, called DS-OptiDoE (DSODE), able to optimise downstream strategies has been developed and it has been published as an open-source tool in the platform Zenodo (DOI: 10.5281/zenodo.6606670). Efficient downstream processes for C3-C6 alcohols through pervaporation, PHB by cell lysis and precipitation/washing, lactic acid using a membrane filtration cascade of ultrafiltration, nanofiltration and reverse osmosis, and formic acid through two successive steps of nanofiltration and reactive liquid-liquid extraction have been developed. In addition, an integrated biocatalytic-chemocatalytic route to convert n-butanol into 2-ethylhexanol and an enzymatic process for ring-opening polymerisation of lactic acid to PLA have been developed.
• Demonstration in industrially relevant conditions: The goal is to demonstrate and validate the developed biological processes in a real industrial environment and with actual flue gasses from the steel mill industry. a mobile gas fermentation pilot plant, Bio Base Mobile Pilot Plant (BBMPP) has been constructed and installed at Arcelor Mittal site. The BBMPP was designed as flexible in operation as possible, though allowing the ability to work with a wide array of microbial strains all requiring process-specific operational procedures. The BBMPP is equipped with 3 bioreactors pressurizable up to 8 barg: a 157L stirred tank reactor or STR, a 24 L STR, and a 10 L trickle-bed reactor or TBR. Even some additional experiments should be performed for optimizing the process, the results obtained in the fermentation of C. necator to produce PHA using real gases are very promising.