Described herein are recombinant microbial host cells comprising biosynthetic pathways and their use in producing oxidation products and downstream products, e.g., melatonin and related compounds, as well as enzyme variants, nucleic acids, vectors and methods useful for preparing and using such cells. In specific aspects, the present invention relates to monooxygenases, e.g., amino acid hydroxylases, with a modified cofactor-dependency, and to enzyme variants and microbial cells providing for an improved supply of cofactors.

Described herein are recombinant microbial host cells comprising biosynthetic pathways and their use in producing oxidation products and downstream products, e.g., melatonin and related compounds, as well as enzyme variants, nucleic acids, vectors and methods useful for preparing and using such cells. In specific aspects, the present invention relates to monooxygenases, e.g., amino acid hydroxylases, with a modified cofactor-dependency, and to enzyme variants and microbial cells providing for an improved supply of cofactors.

The present invention relates to a hydantoinase having an amino acid sequence selected from (i) or (ii), with (i) amino acid sequence selected from SEQ ID NO: 6-20 and SEQ ID NO: 73-119 (ii) amino acid sequence wherein in the amino acid sequence of SEQ ID NO: 6-20 and SEQ ID NO: 73-119, 1 to 75 amino acid residues have been substituted, deleted, inserted and/or added, and wherein further the catalytic activity of the hydantoinase is higher by a factor of at least 1.2 than the catalytic activity of the hydantoinase having amino acid sequence SEQ ID NO: 1. The present invention further relates to a process for preparing amino acids, wherein said hydantoinase is used.

The present disclosure provides methods for preparing -substituted tryptophan compounds. The methods include: combining i) an unsubstituted indole or a substituted indole, ii) a -substituted serine, and iii) a tryptophan synthase -subunit (i.e., a TrpB); and maintaining the resulting mixture under conditions sufficient to form the -substituted tryptophan. The TrpB contains at least one amino acid mutation which promotes formation of an amino-acrylate intermediate. New TrpB variants and new -substituted tryptophan analogs are also described.

A biotechnological production of tryptophan and derivatives thereof, as well as a method for an enhanced microbial L-tryptophan synthesis. In one aspect the invention provides a bacterial cell being genetically modified to express anindole-3-glycerol phosphate synthase, IGPs, the IGPs being less sensitive to inhibition or even being activated by anthranilate compared to the wild type IGPs of the bacterial cell.

The present disclosure provides methods for preparing tryptophans and tryptophan derivatives. The methods include: combining i) an indole substrate or azulene substrate, ii) a serine substrate, and iii) an engineered tryptophan synthase -subunit (TrpB); and maintaining the resulting mixture under conditions sufficient to form the product compound. The engineered TrpB comprises a PLP binding loop mutation, a helix 1 mutation, a strand 7-8 mutation, or a combination thereof. New TrpB variants are also described.

The present invention relates to genetically modified bacteria and methods of optimizing genetically modified bacteria for the production of a metabolite.

The invention provides a method of producing L-tryptophan, the method comprising culturing a L-tryptophan producing microorganism belonging to the Enterobacteriaceae family in a fermentation medium; wherein the L-tryptophan producing microorganism has been modified by enhancing the expression level of the mdfA gene or by enhancing the expression level of an mdfA allele.

This invention involves to Bacillus licheniformis JSC-69 for producing the 5-HTP, deposited as CGMCC NO: 13533; and a method for the producing 5-HTP using Bacillus licheniformis. Bacillus licheniformis JSC-69 said in this invention produces 5-HTP using tryptophan as the substrate, and the transformation efficiency is 95%100%.

This disclosure relates to modified tryptophan synthase and more particularly to modified beta-subunits of tryptophan synthase. The disclosure further relates to cells expressing such modified subunits and methods of producing non-canonical amino acids.