Method for the incorporation of formaldehyde into biomass

A recombinant microorganism expressing enzymes for catalyzing the following sequence of reactions for in vivo incorporation of formaldehyde into carbon compounds that can be assimilated into metabolism:

• (1) condensation of pyruvate with a first formaldehyde into 4-hydroxy-2-oxobutanoic acid (HOB) by an aldolase classified in EC 4.1.2._;
• (2) amination of the thus produced 4-hydroxy-2-oxobutanoic acid (HOB) to produce homoserine by an aminotransferase enzyme classified in EC 2.6.1._ or by an amino acid dehydrogenase classified in EC 1.4.1._;
• (3) phosphorylation of thus produced homoserine to produce o-phosphohomoserine by a homoserine kinase classified in EC 2.7.1.39;
• (4) dephosphorylation of the thus produced o-phosphohomoserine to produce threonine by a threonine synthase classified in EC 4.2.3.1;
• (5) conversion of the thus produced threonine into glycine by a threonine aldolase (selected from the group consisting of a threonine aldolase classified in EC 4.1.2.5, a threonine aldolase classified in EC 4.1.2.6, a threonine aldolase classified in EC 4.1.2.48, and a threonine aldolase classified in EC 4.1.2.49, or by a combination of a threonine dehydrogenase classified in EC 1.1.1.103 and a 2-amino-3-ketybutyrate CoA ligase classified in EC 2.3.1.29;
• (6) condensation of the thus produced glycine with a second formaldehyde to produce serine by a threonine aldolase selected from the group consisting of a threonine aldolase classified in EC 4.1.2.5, a threonine aldolase classified in EC 4.1.2.6, a threonine aldolase classified in EC 4.1.2.48, and a threonine aldolase classified in EC 4.1.2.49;
• and
• (7) deamination of the thus produced serine to produce pyruvate by a serine deaminase classified in EC 4.3.1.17 or a threonine deaminase classified in EC 4.3.1.19, wherein said pyruvate can then be used as a substrate in step (1),
• wherein said microorganism contains at least one heterologous nucleic acid molecule encoding the aldolase catalyzing step (1) and overexpresses the enzyme catalyzing step (6) for the condensation of glycine with formaldehyde to form serine.