Improved biosynthetic production of 2,3-trans-CHD

The invention relates to a process for the biosynthetic production of [5 S ,6 S ]-5,6-dihydroxy-cyclohexa-1,3-diene-1-carboxylic acid (2,3- trans -CHD) in an Escherichia microorganism having increased activity of isochorismate synthase and isochorismatase, and being deficient in activity of 2,3-dihydroxybenzoate synthase, wherein the process is carried out in a chorismate overproducing host microorganism also having decreased glucose dehydrogenase activity. In this improved biosynthetic process, 2,3- trans -CHD is being produced in high yields and at concentrations in the biosynthetic reaction medium of at least 12 g/l. The invention further relates to the use of the supernatant of a process for the biosynthetic production of [5S,6S]-5,6-dihydroxy-cyclohexa-1,3-diene-1-carboxylic acid (2,3-trans-CHD) where the concentration of 2,3- trans -CHD in the process has arrived at a concentration of at least 12 g/l as a source for a co-factor for PQQ dependent enzymes.