399: Optimizing Downstream Processing to Produce a Sustainable Protein Ingredient From Gas-Fermented Cupriavidus Necator

Introduction

The growing demand for sustainable protein sources has highlighted microbial protein-rich biomass production using non-food feedstocks as an environmentally friendly alternative to traditional agriculture. This study explores the potential of Cupriavidus necator, a hydrogen-oxidizing bacterium, produced via gas fermentation, to convert green hydrogen (H₂) and carbon dioxide (CO₂) into single-cell protein. The focus is on optimizing the downstream processing to extract proteins and improve yield, scalability, stability, and safety for food and feed applications.

Methods

Biomass production of C. necator was performed under batch cultivation. Analytical methods determined yield, macromolecular composition, and amino acid profile. Cell disruption was achieved with a French press under different pressure and cycle conditions (50-270 MPa, 1–5 passes, 10–100 g/L biomass concentration) combined with enzymatic pre-treatment. Protein fractions were separated by centrifugation and purified via isoelectric point precipitation, followed by lyophilization.

Results

Depending on cultivation conditions, the dry biomass contained 35–83% crude protein, 0.5–0.9% lipids, 2.6–26% polyhydroxybutyrate (PHB), and 5–7% nucleic acids. Up to 95–98% cell disruption was achieved after 2–3 passes at a pressure of 2.7 kbar with biomass concentrations of 10–100 g/L. Protein recovery efficiency was enhanced using chemical and lysozyme-assisted disruption. Fractionation experiments revealed a soluble protein fraction that could be purified using isoelectric point precipitation, yielding a protein ingredient suitable for formulating climate-resilient foods.

Significance

Gas fermentation offers a unique advantage by decoupling protein production from traditional agriculture, reducing reliance on resource-intensive farming, and minimizing environmental impacts. The high protein yield, combined with a complete amino acid profile, makes C. necator biomass a promising alternative for sustainable food and feed applications.

Authors: Prerana Balasubramanian, Carlos Woern, Lutz Grossmann