Production of polyhydroxybutyrate in switchgrass, a value‐added co‐product in an important lignocellulosic biomass crop

TLDR

Polyhydroxyalkanoate bio‑based plastics derived from renewable resources can reduce petroleum use and lower plastic waste problems because they are biodegradable in soil, compost, and marine environments. This paper reports the successful engineering of switchgrass (Panicum virgatum L.) to synthesize polyhydroxybutyrate (PHB). The authors monitored PHB production in over 400 primary transformants grown in vitro and in glasshouse conditions and analyzed accumulation in the T1 generation from controlled crosses of transgenic plants. Engineered switchgrass produced up to 3.72 % PHB dry weight in leaves and 1.23 % in whole tillers; cellular and whole‑plant distribution analyses identified target areas for improvement, and the study demonstrates the first successful expression of a functional multigene pathway in this high‑yielding crop, confirming its suitability for complex metabolic engineering to produce high‑value biomaterials alongside lignocellulose‑derived biofuels.

Abstract

Polyhydroxyalkanoate bio-based plastics made from renewable resources can reduce petroleum consumption and decrease plastic waste disposal issues as they are inherently biodegradable in soil, compost and marine environments. In this paper, the successful engineering of the biomass crop switchgrass (Panicum virgatum L.) for the synthesis of polyhydroxybutyrate (PHB) is reported. Polymer production was monitored in more than 400 primary transformants grown under in vitro and glasshouse conditions. Plants containing up to 3.72% dry weight of PHB in leaf tissues and 1.23% dry weight of PHB in whole tillers were obtained. Results from the analysis of the polymer distribution at the cellular and whole plant levels are presented, and target areas for the improvement of PHB production are highlighted. Polymer accumulation was also analysed in the T(1) generation obtained from controlled crosses of transgenic plants. This study presents the first successful expression of a functional multigene pathway in switchgrass, and demonstrates that this high-yielding biomass crop is amenable to the complex metabolic engineering strategies necessary to produce high-value biomaterials with lignocellulose-derived biofuels.