Engineered Bacteria Turn Potato Starch Into Biodegradable Bioplastic

Researchers at the University of Barcelona have developed a biodegradable bioplastic from unprocessed potato starch. The material offers a promising alternative to conventional petroleum-based plastics. As a result, it could help reduce dependence on fossil resources while creating value from agricultural by-products.

The study, published in Bioresource Technology, shows how the bacterium Bacillus subtilis can be engineered to produce polyhydroxybutyrate (PHB). This biodegradable biopolymer could be used in packaging, consumer products and other applications that require more sustainable materials.

Turning Potato Starch Into Bioplastic

PHB belongs to a family of bioplastics known as polyhydroxyalkanoates (PHAs). Microorganisms naturally produce these materials from renewable resources. Unlike conventional plastics, PHB can biodegrade under suitable conditions. Consequently, it offers a way to reduce persistent plastic waste.

To improve PHB production, the researchers used CRISPR-Cas9 gene-editing technology. They redesigned the metabolism of Bacillus subtilis, a non-pathogenic bacterium already widely used in industrial biotechnology. The team introduced several genes and optimised their expression. As a result, the bacterium produced much larger quantities of the biopolymer.

A key breakthrough involved the addition of the amyQ gene. This gene enables the bacterium to produce an α-amylase enzyme that breaks down raw potato starch. Therefore, the microorganism can convert unprocessed starch directly into PHB. The entire process takes just 24 hours and requires only a single production step.

Higher Yields With Commercial Potential

Earlier studies achieved only limited PHB production in Bacillus subtilis. However, the newly engineered strain delivered significantly better results. In laboratory-scale cultures, it produced 11.3 g/L of biomass and 5.8 g/L of PHB.

The material accounted for 51.8% of the dry cell weight. Moreover, its purity matched commercial PHB grades. According to the researchers, using inexpensive feedstocks such as potato starch could make bioplastic production more economically viable.

Supporting A Circular Economy

PHB is attracting growing interest as a renewable alternative to conventional plastics. Because it originates from biological resources, it can help close material loops and reduce long-term waste accumulation. In addition, several life-cycle assessments have shown that bio-based plastics can have a lower carbon footprint than many petrochemical plastics. The environmental benefits become even greater when manufacturers use waste-derived feedstocks.

The researchers believe that technologies like this can transform agricultural waste into valuable materials. Consequently, they could support the transition towards a more circular and decarbonised economy. For designers and manufacturers, advances in PHB production may also increase the availability of biodegradable materials for future products and packaging.

Source: University of Barcelona
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