The production of poly-gamma-glutamic acid (gamma-PGA) by Bacillus subtilis NX-2 using a moving bed biofilm reactor (MBBR) system was tested for the first time in this study. Polypropylene TL-2 was chosen as a suitable carrier, and gamma-PGA concentration of 42.7 +/- 0.86 g/L and productivity of 0.59 +/- 0.06 g/(L h) were obtained in batch fermentation. After application of the strategy of dissolved oxygen (DO)-stat feeding, higher gamma-PGA concentration and productivity were achieved than with glucose feedback feeding. Finally, the repeated fed-batch cultures implemented in the MBBR system showed high stability, and the maximal gamma-PGA concentration and productivity of 74.2 g/ L and 1.24 g/(L h) were achieved, respectively. In addition, the promotion of oxygen transfer by an MBBR carrier was well explained by a computational fluid dynamics (CFD) simulation. These results suggest that an MBBR system could be applied to large-scale gamma-PGA production. (C) 2016 Elsevier Ltd. All rights reserved.