Sustainable PHA production in integrated lignocellulose biorefineries

In emerging bioeconomies, the compostable biopolymers polyhydroxyalkanoates (PHAs) are desirable products due to their similarity to petropolymers. While industrial PHA production has been growing rapidly, obtaining a cheap and sustainable carbon source is still a challenge. Among biobased feedstocks, lignocellulose is a cheap, abundant and potentially sustainable carbon source. However, because of its recalcitrance, separation and depolymerization processes that have not reached industrial maturity are usually required. Integrated biorefineries utilize a holistic approach to conversion processes to minimize feedstock price and maximize resource use. This review examines the technical feasibility of merging PHA production and lignocellulose biorefining in integrated processing facilities. Among lignocellulosic feedstocks, wood is a promising carbon source due to its mature industrial infrastructure. Among the lignocellulose components, the hemicellulose fraction is the most promising feedstock for PHA production since it is underutilized and can be combined with bioethanol production from the cellulose fraction. Fractionation processes allow separate recovery of cellulose, hemicellulose and lignin, to which PHA can be added as a co-product.