In a groundbreaking advancement that could revolutionize the plastics industry and mitigate environmental degradation, researchers at the University of Barcelona have successfully engineered the bacterium Bacillus subtilis to produce biodegradable polyhydroxybutyrate (PHB) directly from unprocessed potato starch. This single-step biosynthesis process, achieved within a 24-hour timeframe, represents a significant leap in sustainable bioplastic production, highlighting the potential to drastically reduce reliance on petrochemical plastics that dominate the global market.
Every year, humankind produces hundreds of millions of tonnes of plastic derived from petroleum, most of which contributes to severe pollution problems. Such plastics accumulate in landfills and oceans, posing risks to wildlife and human health, while their incineration exacerbates greenhouse gas emissions driving climate change. The urgent demand for eco-friendly alternatives has propelled scientific efforts toward renewable bioplastics capable of degrading naturally without leaving persistent pollutants behind. The work by the University of Barcelona team arrives at a timely opportunity where biotechnology addresses these challenges by converting abundant, low-cost agricultural by-products into valuable materials.
Bacillus subtilis, already a workhorse in industrial biotechnology for enzyme synthesis and chemical production, emerges as a robust microbial chassis for PHB synthesis. Until now, attempts to exploit this organism’s full potential in biopolymer accumulation have met with limited success, primarily due to intrinsic metabolic constraints and suboptimal expression of relevant biosynthetic genes. This research utilized advanced CRISPR-Cas9 genome editing to rewire metabolic pathways, overcoming bottlenecks that previously capped PHB yields at sub-13% of the bacterial dry cell weight, inadequate for commercial scalability.
By integrating the phaA gene into the bacterial genome and employing controlled expression of the phaRBC operon, the researchers optimized the enzymatic cascade responsible for polymer assembly. In addition, the strategic insertion of the amyQ gene, encoding a potent α-amylase enzyme, empowered B. subtilis to hydrolyze raw potato starch efficiently. This single-step bioconversion eliminated the need for preliminary starch processing, drastically simplifying the production pipeline and cutting operational costs associated with pretreatment and enzyme supplementation.
Experimental flask-scale cultures vividly demonstrated the process’s efficacy, achieving an impressive 11.3 grams per liter biomass concentration with 5.8 grams per liter of PHB synthesis. The resultant biopolymer purity matched or exceeded commercial standards, with PHB constituting 51.8% of the dry cell mass. Such yields, attained within one day, mark a transformative improvement over prior studies, showcasing genetically enhanced B. subtilis as a competitive platform for industrial bioplastic manufacture.
Unlike traditional plastics sourced from finite fossil fuels, PHB is a bio-based polyester that biodegrades into harmless constituents under natural conditions. Its utilization offers a dual environmental benefit: reducing the carbon footprint inherent in petrochemical manufacturing and minimizing persistent plastic waste polluting terrestrial and marine ecosystems. Life-cycle assessments consistently reveal that bioplastics like PHB, especially when manufactured from agricultural residues or waste streams, have substantially lower global warming potential and resource depletion metrics compared to conventional plastics.
This innovative production method exemplifies a circular economy model, wherein low-value crop waste is valorized into high-demand biodegradable materials. By leveraging renewable biomass feedstocks and synthetic biology tools, the approach significantly decarbonizes bioplastic supply chains, offering scalable solutions to pressing environmental crises. The researchers advocate that such integrated bioprocesses hold promise to supplant petrochemical dominance gradually while fostering sustainable industrial development aligned with global climate targets.
Moreover, the safe, non-pathogenic status of B. subtilis and its established use in food and pharmaceutical industries mitigate biosafety concerns, smoothing regulatory pathways for commercial deployment. The genetic modifications introduced are designed to be stable and constitutive, ensuring consistent PHB production under industrial fermentation conditions. This robustness, paired with cost-effective feedstock utilization, positions the method favorably for eventual scale-up and market penetration.
The study, recently published in the journal Bioresource Technology, reflects a collaborative scientific effort led by Professor Pere Picart at the University of Barcelona’s Faculty of Pharmacy and Food Sciences. Contributions from Dr. Mercedes Berlanga and colleagues at the Biodiversity Research Institute further enriched the multidisciplinary expertise driving this breakthrough. Their shared vision underscores biotechnology’s potential to transform sustainable material production through precision genetic engineering and process innovation.
Looking ahead, the team envisions refining the production system to enhance polymer molecular weight control, tailor material properties, and integrate downstream processing for efficient PHB recovery. Coupling this with expanded substrate flexibility could diversify feedstock options, including food waste and other starch-rich residues, magnifying environmental and economic benefits. The integration of bioplastic synthesis into existing agricultural and manufacturing ecosystems could catalyze a more resilient, low-carbon bioeconomy on a global scale.
In conclusion, the engineered Bacillus subtilis platform exemplifies a milestone achievement bridging microbiology, synthetic biology, and green chemistry to tackle the plastic pollution challenge head-on. By converting ubiquitous agricultural waste directly into biodegradable plastics within a streamlined, cost-effective process, this technology offers an inspiring vision for a circular, sustainable future. Continued innovation and investment in such bio-based solutions may well herald the transition from a petrochemical-dependent society toward one harmonized with nature’s regenerative cycles.
Subject of Research: Not applicable
Article Title: One-step polyhydroxybutyrate production from potato starch by engineered Bacillus subtilis
News Publication Date: 20-May-2026
Web References: https://www.sciencedirect.com/science/article/pii/S0960852426010151
References: doi:10.1016/j.biortech.2026.134933.
Image Credits: UNIVERSITY OF BARCELONA
Keywords
Biodegradable bioplastics, Bacillus subtilis, polyhydroxybutyrate (PHB), genetic engineering, CRISPR-Cas9, renewable resources, potato starch, synthetic biology, sustainable materials, circular economy, metabolic pathway optimization, environmental biotechnology
