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Butyric acid and caproic acids production using single and mixed bacterial cultures
* 1 , 2
1  Course of Chemical and Biological Engineering, Division of Sustainable and Environmental Engineering, Muroran Institute of Technology, Hokkaido 050-8585, Japan
2  Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, Colorado, 80523, USA
Academic Editor: Marco Annunziata


In this study, we produced butyric acid (C4) using different bacterial strains (Clostridium beijerinckii, C. acetobutylicum, C. oryzae, and C. kainantoi) belonging to the Clostridium group and acetate as a carbon source. All the strains produced significant amounts of C4, but C. beijerinckii produced 1.54 g/L of C4, which is almost equivalent to the production (1.63 g/L) capacity of C. kluyveri. Further experiments were performed using diluted raw cheese whey (CW) by inoculating mixed bacterial cultures containing Clostridia, Bacillus, and Desulfobacteraceae groups. Clostridium kluyveri was also added to the mixed culture to stimulate the caproic acid (C6) production. Mixed bacterial culture produced 13.97 g/L, 10.83 g/L and 6.81 g/L of C6 when incubated with two times, five times and ten times diluted CW, respectively, within a 20-day incubation period. Compared with our previous study, the C6 production was higher and faster. These results indicated the dilution ratio of CW is an important factor in facilitating C6 production, and higher amounts of fatty acids are produced with the mixed culture than that of a single culture, i.e., C. kluyveri. Results have depicted the potentiality of employing the bio-augmentation strategy for the valorization of bioresources into valuable products like butyric acid and caproic acid.

Keywords: butyric acid, caproic acids, Clostridium kluyveri, mixed culture, cheese whey