In a groundbreaking development that could reshape the energy and chemical industries, researchers have engineered a microbial strain capable of producing styrene, a crucial building block for plastics and resins, through a sustainable and eco-friendly process. This innovation, published in the journal mBio, which translates to ‘Microbiology’, offers a stark contrast to traditional petrochemical methods, which are notorious for their high energy consumption and environmental impact.
At the heart of this research is Ana García-Franco, a scientist at the Experimental Station of Zaidín, part of the Higher Council for Scientific Research in Granada, Spain. García-Franco and her team have harnessed the power of synthetic biology to create a microbial factory that can produce styrene from sugars at room temperature and ambient pressure. “This approach not only reduces carbon emissions but also significantly cuts down on energy consumption,” García-Franco explained. “We’re talking about a potential reduction of up to 90% compared to conventional methods.”
The key to this breakthrough lies in the bacterium Pseudomonas putida DOT-T1E, known for its remarkable tolerance to solvents. The researchers engineered this strain to produce styrene in a two-step process. First, phenylalanine is converted into trans-cinnamate using phenylalanine ammonia lyase enzymes. The second step, decarboxylation of trans-cinnamate to styrene, is where the real innovation lies. This step has traditionally been challenging because trans-cinnamate decarboxylases have only been found in fungi.
To overcome this hurdle, García-Franco and her team designed a novel protein called PSC1. This protein is a consensus design, meaning it was created by aligning multiple fungal ferulate decarboxylases and identifying the most common sequences. The result is a highly efficient enzyme that can decarboxylate trans-cinnamate to produce styrene.
PSC1 is a globular dimer with a molecular mass of 104.7 kDa and exhibits high thermal stability, with a melting temperature of 63°C. It remains active at temperatures up to 50°C, making it robust for industrial applications. The crystal structure of PSC1, determined at 2.1 Å resolution, reveals a homodimer with three domains per monomer. A crucial hydrophobic pocket in domain 2 is essential for cofactor and substrate binding, and mutagenesis studies have identified key amino acids—Arg175, Glu280, and Glu285—that are vital for catalysis.
The implications of this research are far-reaching. The petrochemical industry is one of the most polluting sectors, relying on extreme temperatures, high pressure, and toxic catalysts. Synthetic biology offers a greener alternative, enabling the production of chemicals through cell factories that operate under much milder conditions. “This technology has the potential to revolutionize the way we produce aromatic compounds,” García-Franco said. “It’s not just about styrene; the principles we’ve demonstrated can be applied to a wide range of chemicals.”
The energy sector, in particular, stands to benefit significantly from this innovation. The production of styrene and other aromatic compounds is a critical component of the chemical industry, which in turn is a major consumer of energy. By shifting to microbial biosynthesis, companies can reduce their carbon footprint and energy costs, making their operations more sustainable and economically viable.
Moreover, this research paves the way for future developments in synthetic biology. The design and engineering of novel enzymes like PSC1 open up new possibilities for creating microbial factories that can produce a variety of valuable compounds. As García-Franco and her team continue to refine their methods, we can expect to see more breakthroughs that will further integrate synthetic biology into the energy and chemical industries.
This study, published in mBio, marks a significant step forward in the quest for sustainable chemical production. By leveraging the power of synthetic biology, researchers are not only addressing environmental concerns but also driving innovation in the energy sector. The future of chemical production may well lie in the hands of microbes, and García-Franco’s work is leading the way.