The present invention relates to a recombinant microorganism which exhibits i) a conversion activity from D-ribulose-5-phosphate into D-arabinose-5-phosphate, increased in comparison with the same, non-modified microorganism; ii) a cleavage catalysis activity from D-arabinose-5-phosphate into D-glyceraldehyde-3-phosphate and glycolaldehyde, increased in comparison with the same, non-modified microorganism; iii) an oxidation activity from glycolaldehyde into glycolate, increased in comparison with the same, non-modified microorganism; and iv) an oxidation activity from glyceraldehyde-3-phosphate into 1,3-bisphosphoglycerate, decreased in comparison with the same, non-modified microorganism. The present invention also relates to a process for preparing glycolic acid from pentoses and/or hexoses, using such a recombinant microorganism. The present invention also relates to a process for producing glycolic acid involving a biomass production phase and a bioconversion phase from hexoses and/or pentoses into glycolic acid.