Microorganism selected from Gluconobacter, Gluconacetobacter, Acetobacter or Ketogulonicigenium, wherein a gene encoding a polypeptide with the activity of a repressor of L-sorbosone dehydrogenase (SNDH) and L-sorbose dehydrogenase (SDH) is disrupted. The gene has a polynucleotide selected from polynucleotides encoding a polypeptide comprising the amino acid sequence of which is represented by SEQ ID NO:2, polynucleotide comprising the nucleotide sequence according to SEQ ID NO:1, polynucleotides the complementary strand of which hybridizes under stringent conditions to a polynucleotide as defined above and which encodes a polypeptide with the activity of a repressor of SNDH and SDH. The microorganism produces at least 10% more Vitamin C and/or 2-KGA from L-sorbose compared to a microorganism wherein the repressor is intact.