Acetic acid bacteria and Pseudomonas savastanoi were the cultures initially observed to produce gluconic acid.
Unlike in fungi, in bacteria the reaction is carried out by glucose dehydrogenase (GDH, E.C. 1.1.99.17) that oxidises glucose to gluconic acid, which is further oxidised to 2-ketogluconate by gluconic acid dehydrogenase (GADH).