Every year, hundreds of millions of tonnes of petrochemical-based plastics are produced, much of which ends up in the environment or is incinerated. This exacerbates greenhouse gas emissions and the environmental crisis caused by plastic pollution. Now, a study led by the University of Barcelona has produced a biodegradable bioplastic of high industrial value - polyhydroxybutyrate or PHB - from unprocessed potato starch in a single 24-hour step, a strategic breakthrough that could help reduce dependence on oil and the volume of persistent plastic waste.
The study thus establishes that the bacterium Bacillus subtilis is a robust platform of great industrial interest for producing PHB - a biodegradable biopolymer derived from renewable sources - from potato starch, an abundant and low-cost agricultural by-product.
The paper, published in the journal Bioresource Technology , is led by Pere Picart, a professor at the UB's Faculty of Pharmacy and Food Sciences, with significant contributions from Mercedes Berlanga, from the same faculty and the UB's Biodiversity Research Institute (IRBio).
Biodegradable bioplastics made from renewable resources
In this study, the team worked with the bacterium Bacillus subtilis, a safe microorganism widely used in industrial biotechnology to produce enzymes and chemicals.
"Commercial production of PHB requires microbial hosts that are non-pathogenic, genetically tractable, fast-growing, metabolically robust and capable of utilising a variety of carbon sources," the authors explain.
Until now, the potential of Bacillus subtilis to produce polyhydroxybutyrate (PHB) had remained largely unexplored, and systematic metabolic engineering strategies to enable high accumulation of this polymer in the bacterium were still lacking.
Using CRISPR-Cas9-based genetic engineering techniques, the team has redesigned the metabolism of B. subtilis to enhance biopolymer production. "Previous studies showed that the bacterium's capacity to produce PHB was limited, with accumulations below 13% of dry cell weight," the team notes. "These low yields required further optimization of pathway expression and polymer granule formation to fully exploit B. subtilis."
