Valorisation of CO 2 -rich off-gases to biopolymers through biotechnological process

Abstract

As one of the key enabling technologies, industrial biotechnology has a high potential to tackle harmful CO₂ emissions and to turn CO₂ into a valuable commodity. So far, experimental work mainly focused on the bioconversion of pure CO₂ to chemicals and plastics and little is known about the tolerance of the bioprocesses to the presence of impurities. This work is the first to investigate the impact of real CO₂-rich off-gases on autotrophic production of polyhydroxybutyrate. To this end, two-phase heterotrophic-autotrophic fermentation experiments were set up, consisting of heterothrophic cell mass growth using glucose as substrate followed by autotrophic biopolymer production using either pure synthetic CO₂ or industrial off-gases sampled at two point sources. The use of real off-gases did not affect the bacterial performance. High biopolymer content (up to 73%) and productivities (up to 0.227 g/lh) were obtained. Characterisation of the polymers showed that all biopolymers had similar properties, independent of the CO₂ source. Moreover, the CO₂-derived biopolymers' properties were comparable to commercial ones and biopolymers reported in literature, which are all produced from organic carbon sources.