Production of tetrapyrrole compounds and vitamin B₁₂ using genetically engineering of Propionibacterium freudenreichii. An overview

Propionibacterium freudenreichii is a commercially important bacterium that is used in the production of cheeses, cobalamin (vitamin B₁₂) and propionic acid. Metabolic engineering using genetically improved strains will make the fermentation process more economical and also enhance the quality of the products. Host-vector systems and expression vectors using strong promoters from P. freudenreichii were developed in propionibacteria. By using these expression vectors and amplification of various genes, productions of 5-aminolevulinic acid, tetrapyrrole compounds and vitamin B₁₂ were reported. Here, we review the advancement of genetic engineering in P. freudenreichii in recent years, covering the molecular aspects of the formation of tetrapyrrole compounds and vitamin B12.