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New PROMICON paper addresses sustainable PHA production: Challenges, progress, and future perspectives

28 June 2024
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Amid growing environmental concerns over conventional petroleum-based plastics, the search for sustainable alternatives has become increasingly important. In this regard, PROMICON is pleased to announce the publication of a new paper by one of our partners - UPC, focusing on the production of polyhydroxyalkanoates (PHA) - Challenges, progress, and future perspectives for cyanobacterial polyhydroxyalkanoate production.

The paper highlights how cyanobacteria – photosynthetic organisms that produce PHA from CO2 and sunlight – can offer a cost-effective and environmentally friendly alternative to traditional petroleum-based plastics. Unlike heterotrophic bacteria, cyanobacteria use inorganic carbon sources for growth and do not require intensive aeration for oxygenation. Additionally, various copolymers with customisable properties can be produced by supplementing cultures with precursors such as propionate, acetate, and valerate. 

The paper covers recent advances in PHA production, including insights into the metabolism interplay between PHA and glycogen, new cultivation strategies to enhance PHA accumulation, and improved purification processes. It also discusses the challenges and potential solutions for industrial-scale PHA production, as well as underscores the reliance of 21st-century industries on plastics, highlighting the environmental challenges posed by conventional petroleum-based plastics due to their limited biodegradability and pollution issues. PHA offers a promising alternative as it can degrade in various environments such as marine waters, freshwaters, landfills, soils, or home composting devices. It also has properties similar to conventional polymers and is processable with existing techniques.

According to the paper, achieving industrial-scale PHA production with cyanobacteria requires comprehensive workflow optimisation, from cultivation and stimulation of PHA production to extraction and purification. It notes that much of the existing literature focuses on isolated aspects of the process, leaving uncertainties about the overall feasibility. The paper identifies the need for increased biomass productivity, improved PHA accumulation, and better recovery methods, alongside addressing the gaps in fundamental knowledge about the metabolic functions and regulations critical to developing viable industrial processes.

For more detailed information, you can access the full article here.

Schematic representation of the PHA production process using cyanobacteria. First, cyanobacteria are grown with light and sufficient nutrients (growth phase). Nutrients are reduced with time. Next, the biomass is separated from the cultivation medium and placed in a new medium without N or/and P (two-step cultivation). It is possible to omit the separation step by optimizing the initial nutrient concentration so they are completely exhausted by the end of the growth phase. Without nutrients, the accumulation phase starts and other PHA-stimulating conditions can be applied (e.g., high salinity, acetate, light availability). During this phase, glycogen and PHAs accumulate. If the chlorosis persists for a long time, glycogen is degraded and converted into PHAs