La production de matières plastiques a dépassé les 390 millions de tonnes par an à partir de 2021 et ne cesse d’augmenter. Ces matériaux aux propriétés versatiles et aux coûts de fabrication faibles s
Gabrielle Derippe, chercheur·e au sein de IRDL (Institut National Polytechnique de Bretagne).
Thèse soutenue en 2023 à l'école doctorale École doctorale Sciences Pour l'Ingénieur (Lorient ; 2022-....).
Référencée dans le réseau ABES/STAR, cette thèse répond aux critères de rigueur de l'enseignement supérieur français.
Plastic pollution has become a major environmental issue, with over 390 million tons of plastics produced each year. This alarming situation has disastrous consequences for marine ecosystems, wildlife, and human health. Polyhydroxyalkanoates (PHA) are emerging as a promising alternative, particularly due to their biodegradability. Indeed, these biopolymers, produced by bacteria, can naturally decompose in the environment, thereby reducing the accumulation of plastic waste. Gabrielle Derippe, at the Institute for Research and Development in Coastal Areas (IRDL), has conducted extensive research on the production of PHA by marine bacterial strains, focusing on A. plasticoclasticus MED1. This strain has demonstrated its ability to produce PHAs, such as polyhydroxybutyrate (PHB) and polyhydroxyhexanoate (PHN), while being isolated in a marine environment, highlighting its potential under real marine pollution conditions.
The results of this research are significant and pave the way for new strategies to combat plastic pollution. They reveal not only the metabolic pathways involved in the production and biodegradation of PHAs but also the ability of certain bacteria to degrade these biopolymers in marine conditions. For example, previous studies have shown that strains of Pseudomonas and Bacillus can also degrade conventional plastics, but the specificity of A. plasticoclasticus MED1 in a marine environment is particularly promising. This opens interesting prospects for combating plastic pollution, as understanding the mechanisms of biodegradation could lead to the development of more effective solutions for managing plastic waste in marine environments.
The strategic recommendations of this thesis include exploring alternative growth substrates for bacterial strains. For instance, using marine organic waste as substrates could not only promote PHA production but also contribute to the valorization of marine resources. Furthermore, using genomic tools to quickly identify genes associated with PHA production could revolutionize how we cultivate these bacteria. This could not only improve the production of these biopolymers but also enhance their use in environmental and industrial applications, such as in the manufacture of biodegradable packaging materials or medical devices.
It is crucial to ask the question: how can these advances be integrated into public policies to encourage the use of PHAs? Policymakers should consider incentives for companies that adopt these biodegradable materials while supporting research and development in this field. For example, subsidies could be granted to companies investing in PHA production, or regulations could be implemented to limit the use of non-biodegradable plastics. Additionally, awareness campaigns could be launched to inform the general public about the benefits of PHAs and encourage their adoption.
In summary, Gabrielle Derippe's research highlights the opportunities offered by PHAs in the fight against plastic pollution. The implications of this study go beyond the mere production of biopolymers; they touch on how we can rethink our approach to plastic materials and their impact on the environment. By integrating this new knowledge into waste management strategies and environmental policies, we can hope for a future where harmful plastics are replaced by sustainable alternatives, thereby contributing to the preservation of our oceans and our planet. It is time to act and transform these scientific discoveries into concrete actions for a cleaner and more environmentally friendly world.
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Sources et accès
Gabrielle Derippe. Les polyhydroxyalcanoates (PHA) en milieu marin : production bactérienne à façon et biodégradabilité : étude des communautés bactériennes et des mécanismes de biodégradation impliqués. Génie des procédés. Université de Bretagne Sud, 2023. Français. ⟨NNT : 2023LORIS671⟩. ⟨tel-04624309⟩