The co-cultures of Ketogulonigenium vulgare and Bacillus cereus were subcultured daily for a total of 150 transfers. The yield of 2-keto-gulonic acid (2-KGA) and medium pH in the co-cultures were measured. We found that the serial subcultivation increased the yield of 2-KGA from 77% (original co-culture) to 93% (the 150th transfer of transferred co-culture). The resulted strains are of industrial interests for vitamin C production. (C) 2012 Elsevier Ltd. All rights reserved.