BACKGROUNDButyric acid is an important chemical with wide industrial applications, but large-scale bio-production still requires an efficient bioprocess. For this purpose, one novel moving fibrous-bed bioreactor (MFBB) was developed in this work for economical production of butyric acid. RESULTSThe cells of Clostridium tyrobutyricum were immobilized on a fibrous matrix packed in porous levitated sphere carriers. Each carrier was packed with a fiber quantity 2 cm x 6 cm (0.42 g) and was rotated at 100 rpm in a stirred-tank fermentor having pH and temperature controls. Batch and repeated-batch fermentations were carried out to produce butyric acid with a high yield (0.48 0.015 g g(-1)). Subsequent fed-batch fermentation using the MFBB resulted in a high concentration of butyric acid (65.4 +/- 1.4 g L-1). This novel MFBB could be employed to produce high concentration butyric acid (64.5 +/- 1.2 g L-1) by a simple repeated-batch addition of a high concentration of glucose (>100 g L-1). CONCLUSIONS

The MFBB system developed could practically and economically produce butyric acid from glucose for long-term operation. (c) 2013 Society of Chemical Industry