Long‐term production of butyric acid through immobilization of Clostridium tyrobutyricum in a moving fibrous‐bed bioreactor ( MFBB )

BACKGROUND Butyric 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. RESULTS The 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 × 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. © 2013 Society of Chemical Industry