HotCircularity: Harnessing thermophilic Archaea for production of biodegradable alternatives to microplastics from biodiesel waste byproducts

In this Volkswagen Stiftung funded project, we utilize waste products from the biodiesel industry by producing high-value archaeal lipids and upcycling wastewater using microalgae to generate nutrient-rich biomass for fertilization.

Motivation

Plastic materials are essential for modern life, but their massive production and improper disposal are causing environmental pollution. In agriculture, microplastics are used for the encapsulation of soil improvers, pesticides, and seeds, significantly contributing to soil contamination and potentially harming human health. To address this, the EU is considering bans on non-biodegradable polymer coatings, highlighting the urgent need for biodegradable alternatives. 
Current alternatives to microplastics face limitations. Tetraether lipids (TELs) from the thermoacidophilic archaeon Sulfolobus acidocaldarius offer a highly stable, biodegradable option. The HotCircularity project aims to engineer S. acidocaldarius and optimize bioprocesses to convert waste by-products like crude glycerol and bio-acetate into TEL-based archaeosomes. To design a circular bioprocess, the project also aims to use the spent cultivation medium and the CO₂ generated during fermentation of S. acidocaldarius to feed the microalgae Galdieria sulphuraria, which can then be processed into bio-fertilizers. This creates a fully integrated bioprocess that reduces waste and provides biodegradable alternatives to microplastics in agriculture. 

Goals

• Development of a scalable bioprocess for the continuous cultivation of S. acidocaldarius utilizing crude glycerol from biodiesel production.

• Establishment of a circular bioprocess by utilizing spent cultivation media and produced CO2 for microalgal growth and biofertilizer production.

• Demonstration of the suitability of TEL-based archaeosomes as biodegradable alternatives to microplastics in agricultural applications. 

Sources

1. Plastics Europe - Enabling a sustainable future, Plastics the fast facts 2023. (https://www.plasticseurope.org/en/about-plastics/what-areplastics/how-plastics-are-made). (2023), access date 13.02.2024

2. R. Geyer, J. R. Jambeck, K. L. Law, Production, use, and fate of all plastics ever made. Sci Adv 3, e1700782 (2017).

3. K. Istel, M. Jedelhauser, Naturschutzbund Deutschland (NABU) e. V., Plastics in soils - plastic emissions from agriculture and horticulture in Germany. The Fact Sheet, Ed. H. Pfüller, 1st edition 07/2021. www.nabu.de/imperia/md/content/nabude/ konsumressourcenmuell/2021_factsheet_nabu_plastics_soils_english.pdf, access date 13.02.2024

4. T. Hofmann et al., Plastics can be used more sustainably in agriculture. Communications Earth & Environment 4, 332 (2023).

5. A. Khan et al., Ecological risks of microplastics contamination with green solutions and future perspectives. Sci Total Environ 899, 165688 (2023).

6. K. Blackburn, D. Green, The potential effects of microplastics on human health: What is known and what is unknown. Ambio 51, 518-530 (2022).

7. Plastics in Agriculture - an Environmental Challenge, United Nations Environment Programme, Foresight Brief, 029, (2022) (https://wedocs.unep.org/20.500.11822/404032022), access date 13.02.2024

8. T. Pirzada et al., Recent advances in biodegradable matrices for active ingredient release in crop protection: Towards attaining sustainability in agriculture. Current Opinion in Colloid & Interface Science 48, 121-136 (2020).

9. J. Quehenberger, L. Shen, S. V. Albers, B. Siebers, O. Spadiut, Sulfolobus - A Potential Key Organism in Future Biotechnology. Front Microbiol 8, 2474 (2017).

10. T. Attarbachi, M. D. Kingsley, V. Spallina, New trends on crude glycerol purification: A review. Fuel 340, 127485 (2023).