New coculture system of Clostridium spp. and Megasphaera hexanoica using submerged hollow-fiber membrane bioreactors for caproic acid production.

Graphical abstract Highlights • The first attempt to produce caproic acid by M. hexanoica with s-HF/MBRs. • Caproic acid of 10.08 g L−1 was produced with the fastest productivity of 0.69 g L−1 h−1. • The s-HF/MBRs showing potentials on caproic acid production by co-culture process. Abstract In this study, a coculture bioprocess was developed with Clostridium strains producing butyric acid and Megasphaera hexanoica producing caproic acid from the butyric acid. The two bacterial strains were each cultivated in two submerged hollow-fiber membrane bioreactors (s-HF/MBRs), separately. Each fermentation broth was filtered through the membrane modules, and the filtered broth was either interchanged on another reactor or obtained sequentially through. Using s-HF/MBRs, the caproic acid concentration increased to 10.08 g L−1, with the fastest productivity of 0.69 g L−1 h−1, which higher than that previously reported. [ABSTRACT FROM AUTHOR]