Life cycle assessment of microbial protein production using hybrid living materials

Description

Hybrid living materials (HLMs) are systems that integrate artificial components, such as porous membranes, with living elements, such as microbial biofilm consortia. This study aims to design and develop HLMs that capture and utilise carbon dioxide (CO2) and methane (CH4), while producing protein-rich microbial biomass suitable for use in animal feed. To assemble an optimum synthetic microbial consortium for microbial protein production, porous recycled PET membrane and microbial consortia of photoautotrophic and methanotrophic strains were utilised. Methanotrophs use CH₄ as a carbon and energy source, while photoautotrophs use light and CO₂. The resulting system offers a potential solution to interconnected global challenges: climate change, plastic pollution, and protein demand in food systems.
Alongside technical development, the study performs a life cycle assessment (LCA) to evaluate the environmental performance of HLM production. It (1) identifies environmental hotspots at the laboratory scale and proposes mitigation scenarios, (2) examines conditions under which the environmental performance of HLMs exceeds that of alternative phototrophic or methanotrophic systems, and (3) establishes a baseline for comparing HLM-derived protein with conventional protein sources such as fishmeal and soymeal.
LCA is based on two interlinked production processes: the development of recycled PET membrane and the production of microbial proteins. The core process is microbial protein production. The system boundary is cradle-to-gate, covering stages from raw material acquisition, microbial pre-cultivation, biofilm formation, biomass harvesting (via mechanical scraping), to drying. Recycled PET membrane production includes PET processing, membrane preparation, and subsequent modification.
Two functional units (FUs) were applied: FU1 – production of 1 kg of microbial protein via HLMs, used for identifying process-level environmental hotspots; and FU2 – production of 1 kg of protein equivalent to that in fishmeal, used for benchmarking against conventional proteins. The LCA was conducted using SimaPro software, Ecoinvent 3.10 database, and the ReCiPe 2016 Midpoint method.
Results show that membrane preparation is the main contributor (48%) to total environmental impact in membrane production, followed by membrane modification (30%) and PET processing (22%). Key impacts are associated with the solvent N-methyl-2-pyrrolidone and electricity use. For microbial protein production, electricity accounts for 73% of the environmental burden. Compared to fishmeal and soymeal, HLM protein shows environmental benefits in land and water use. Soymeal has the highest land use impact, while HLMs return water to the system, resulting in net water savings.
The LCA results obtained are based on empirical data from the lab-scale experiments. Future steps include scaling up experiments to pilot-scale, reducing electricity use in energy-intensive steps, improving membrane durability, and evaluating alternative biomass harvesting methods. A carbon footprint analysis will also be conducted to assess HLMs’ potential for greenhouse gas mitigation.

Period	24 Sept 2025 → 27 Sept 2025
Event title	5th International Conference: Rethink Food Resources, Losses, and Waste
Event type	Conference
Conference number	5
Location	Athens, GreeceShow on map
Degree of Recognition	International