Production of polyhydroxybutyrate in sugarcane

Area of Science:

• Biotechnology
• Plant Molecular Biology
• Polymer Science

Background:

• Polyhydroxybutyrate (PHB) is a biodegradable bacterial polyester with potential industrial applications.
• Engineering plants for PHB production offers a sustainable alternative to petrochemical plastics.
• Sugarcane is a high-biomass crop with potential for large-scale biopolymer synthesis.

Purpose of the Study:

• To engineer sugarcane for the production of polyhydroxybutyrate (PHB).
• To investigate the subcellular localization (cytosol, mitochondria, plastids) of PHB biosynthesis enzymes.
• To evaluate PHB accumulation levels and potential effects on plant physiology.

Main Methods:

• Transgenic sugarcane lines were created expressing PHB biosynthesis genes from Ralstonia eutropha.
• Enzymes were targeted to different cellular compartments: cytosol, mitochondria, and plastids.
• PHB accumulation was quantified using microscopy and biochemical analysis.

Main Results:

• PHB accumulated in leaves of plastidic lines up to 1.88% of dry weight without apparent negative effects.
• Trace amounts of PHB were found in cytosolic lines; none were detected in mitochondrial lines.
• Lower PHB concentrations in culm internodes were attributed to cellular dilution, not protein expression limits.

Conclusions:

• Plastid-targeted expression is a viable strategy for PHB production in sugarcane leaves.
• Further strategies are needed to enhance PHB yields in non-photosynthetic tissues like culms.
• Optimizing PHB production in sugarcane could lead to sustainable bioplastic manufacturing.