Work

Production of hydrogen from crude glycerol via an integrated process of L-malate biosynthesis by Escherichia coli and photofermentation by Rhodobacter capsulatus

Year: 2025

Type: article

Abstract: Biorefinery is an innovative concept for resource utilization. To further increase its efficiency, the integration of different biomass conversion technologies (integrated biorefinery) is essential. Biodiesel, a traditional biofuel, generates glycerol as an inevitable byproduct; making it an attractive carbon source for biorefineries due to its abundance, low price, and high degree of reduction. In this work, we propose an integrated two-step process of dark fermentation with Escherichia coli to produce L-malate from glycerol and photofermentation by Rhodobacter capsulatus to convert this L-malate into hydrogen, a clean and sustainable energy carrier. To this end, we optimized an E. coli L-malate-producing strain by overexpressing GlpK in the M4-Δ iclr /pBAD- pck strain and scale up the process from shake flask to bioreactor using waste crude glycerol from a biodiesel biorefinery instead of pure glycerol. Under the optimized conditions, E. coli produced up to 11 g/L L-malate in 24 h. The culture medium from this dark fermentation was used to formulate an L-malate enriched medium for Rhodobacter that led to the production of 58.0 ± 6 mM H 2 in 90 h. Graphical abstract

Source: Microbial Cell Factories

DOI: 10.1186/s12934-025-02866-y

Authors: Jose L. Marcos, Gema Cabrera, Daniel F. Hernandez, Beatriz Luque, Antonio Valle, Jorge Bolivar

Institution: Universidad de Cádiz

Language: English

Topic: Microbial Metabolic Engineering and Bioproduction

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDGs: Affordable and clean energy, Responsible consumption and production, Climate action, Industry, innovation and infrastructure

Open Access status: gold

Estimated APC paid: $3,590