This study was published in the journal Nature Biotechnology, with the doi 10.1038/s41587-024-02267-3. The corresponding authors are Haihong Chen and Yaohong Wang from East China University of Science and Technology, and the publication date is April 26, 2024. The article investigates the high-yield production of chlorophyll through metabolic engineering and biocatalysis.

Research Background

Chlorophyll and its derivatives have wide applications in medicine, food, energy, and materials, but efficient production of these compounds faces significant challenges. The researchers utilized the purple non-sulfur photosynthetic bacterium Rhodobacter sphaeroides as an efficient cell factory and combined enzymatic catalysis with metabolic engineering to produce chlorophyll compounds.

Research Process

Process Design

The research process includes steps such as gene editing, fermentation promotion, metabolic regulation, and enzymatic catalysis.

Gene Editing

The research team used genome-wide CRISPRi screening to identify the target gene heMN in R. sphaeroides, which provided the possibility of improving the production of coproporphyrin III (CPIII).

Fermentation Promotion

By applying temporal regulation of the PrrAB two-component system and a fed-batch fermentation strategy, a high concentration of CPIII production was achieved, reaching 16.5 grams per liter.

Metabolic Regulation

The study regulated metabolic pathways and further improved CPIII production through the adaptation of activation systems and research on the global anaerobic regulator FnRL.

Enzymatic Catalysis

After screening and engineering optimization of high-activity metal chelatases and coproporphyrinogen decarboxylase, various metal porphyrins, including heme and the anti-tumor agent zincphyrin, were synthesized in a 5-liter bioreactor through enzymatic catalysis.

Main Results

The production of CPIII was significantly increased in fed-batch fermentation, and through subsequent enzymatic catalysis, the synthesis of various metal porphyrins was successfully achieved. Heme and zincphyrin were produced in a 5-liter bioreactor following a 200-liter pilot-scale fermentation and the establishment of the CPIII purification process.

Conclusion

This study provides a new pathway for the bio-manufacturing of high-yield porphyrins and related compounds, demonstrating both the potential for large-scale production and the economic feasibility of combining engineered cell factories with in vitro enzymatic catalysis for practical applications.

Significance of the Research

This innovative approach will aid in the large-scale production of heme and other valuable porphyrin compounds in an environmentally friendly and efficient manner, thereby promoting the development of related industries such as pharmaceuticals, food additives, and synthetic meat.

Special Notes

This study employed CRISPR interference (CRISPRi) and high-throughput screening technologies, laying the foundation for further development and optimization of microbial cell factories. Additionally, the proposed techno-economic analysis for assessing industrial potential and financial feasibility provides a new benchmark in the field of porphyrin production.