Butyric Acid and Caproic Acid Production Using Single and Mixed Bacterial Cultures

Abstract

In this study, we explored different bacterial strains (Clostridium beijerinckii, C. acetobutylicum, C. oryzae, and C. kainantoi) belonging to the Clostridium group and produced butyric acid (C4) using 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 capacity (1.63 g/L) 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 added to the mixed culture, and it stimulated 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 to our previous study, the C6 production was higher and faster. These results indicated the dilution ratio of CW is an important factor in facilitating the C6 production, and higher fatty acids are produced with mixed culture than that of a single culture, i.e., C. kluyveri. Results have depicted the potential of employing the bio-augmentation strategy for the valorization of bioresources into valuable products like butyric acid and caproic acid.

Keywords

• butyric acid
• caproic acid
• <i>C. kluyveri</i>
• mixed culture
• PHB
• biomass