A recombinant microorganism includes a transgene encoding a polypeptide of a Type II biotin synthase, wherein a holo-protein of the Type II biotin synthase comprises per polypeptide chain a first [4Fe—4S] cluster (radical SAM (RS) cluster) coordinated to a CxxxCxxC motif in the polypeptide chain and a second [4Fe—4S] cluster. The Type II biotin synthase contains a serine to cysteine swap in its holo-protein amino acid sequence, that is the amino acid at the position corresponding to Ser-43 in the E. coli K12 Type I biotin synthase holo-protein is a Cysteine and the amino acid corresponding to Cys-97 in the E. coli K12 Type I biotin synthase holo-protein is a Serine. A method for producing biotin includes cultivating the recombinant microorganism in a growth medium to produce a culture; and recovering biotin from the culture.

The invention provides a genetically modified bacterial cell capable of improved iron-sulfur cluster delivery, characterized by a modified gene encoding a mutant Iron Sulfur Cluster Regulator (IscR) as well as one or more transgenes encoding polypeptides that enhance the biosynthesis of either biotin, lipoic acid or thiamine. The invention provides a method for producing either biotin, lipoic acid or thiamine using the genetically modified bacterium of the invention; as well as for the use of the genetically modified bacterial cell for either biotin, lipoic acid or thiamine production.

The invention relates to a genetically modified prokaryotic cell capable of improved iron-sulfur cluster delivery, characterized by a modified gene encoding a mutant Iron Sulfur Cluster Regulator (IscR) and one or more transgenes or upregulated endogenous genes encoding iron-sulfur (Fe—S) cluster polypeptides or proteins that catalyze complex radical-mediated molecular rearrangements, electron transfer, radical or non-redox reactions, sulfur donation or perform regulatory functions. The prokaryotic cells are characterized by enhanced activity of these iron-sulfur (Fe—S) cluster polypeptides, enhancing their respective functional capacity, and facilitating enhanced yields of compounds in free and protein-bound forms, including heme, hemoproteins, tetrapyrroles, B vitamins, amino acids, δ-aminolevulinic acid, biofuels, isoprenoids, pyrroloquinoline quinone, ammonia, indigo, or their precursors, whose biosynthesis depends on their activity. The invention further relates to a method for producing said compounds or their precursors using the genetically modified prokaryotic cell of the invention, and the use of the genetically modified prokaryotic cell.