Engineered Microbial Carbon-Capture Pathways for Sustainable Biomanufacturing of Bioplastics

Abstract

The global environmental crisis provoked by plastics made of petroleum products demonstrates that the alternatives must be sustainable and biodegradable. Microbial fermentation is a promising source of bioplastics, though more established technology uses sugar- and biomass-derived feedstocks which compete with agriculture and increase the cost of production. This article aims to evaluate how bioplastic production can be revolutionized by using engineered microbial carbon-capture pathways to use CO₂ and industrial off-gases as major sources of carbons. The review methodologically summarizes the current progress in metabolic engineering and synthetic biology, discussing natural biosynthetic pathways like the CalvinBensonBassham and the WoodLjungdahl cycles, synthetic pathways like the CETCH cycle or the reductive glycine pathway. The efficiency of carbon fixation is compared, along with the integration of the pathways into microbial hosts, and connection with subsequent bioplastic biosynthesis, i.e. polyhydroxyalkanoates (PHAs) and polylactic acid (PLA). The outcomes of the latest experimental and pilot-scale research indicate that the engineered strains have the potential of reaching as high as 30 percent cost reduction and 50-60 percent lower CO 2 emission, to the production of bioplastics, as compared to the conventional bioplastic production. Moreover, the analysis of techno-economic and lifecycle shows the possibility of climate-positive production in case of incorporating renewable energy sources. The conclusions highlight both opportunities and challenges: on the one hand, improvements in pathway efficiency and bioreactor design is driving progress faster, on the other hand, there are still problems with enzyme kinetics, energy requirements, and scale implementations. This review places microbial carbon-capture biomanufacturing as a disruptive platform in the bioeconomy of the U.S. and globally, and a promising pathway to sustainable, circular, and low-carbon plastic replacement.