Enhancement of Biobutanol Production by Butyric Acid Addition Using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564)

Butanol is an important industrial chemical and has gained attention as an important fuel because of its advantages of being less corrosive and water tolerant as compared to the ethanol. This study revealed the effects of butyric acid as an additive on growth and Acetone-butanol-ethanol (ABE) production using batch culture of Clostridium saccharoperbutylacetonicum N1-4. Different combinations of glucose and butyric acid were studied to finalize the best productive ratio for ABE and butanol production. The highest ABE and butanol production was obtained when 4 g L-1 of butyric acid was used in the presence of 30 g L-1 of glucose. The inhibitory effects of butyric acid on bacterial growth were also investigated using C. saccharoperbutylacetonicum N1-4 and mild inhibitory effects were found at high butyric acid concentration. On the other hand, no linear correlation between butyric acid and butanol production was observed. Production of 17.76 g L-1 butanol with a productivity of 0.15 g L-1 h-1 from 4 g L-1 of butyric acid proved the ability of C. saccharoperbutylacetonicum N1-4 to be tolerant to the certain concentration of butyric acid for the enhanced butanol production. Butyric acid was not only contributing as an additive or stimulating agent to the butanol pathway but also was being utilized as a co-substrate. Enhanced butanol production using growing cells of C. saccharoperbutylacetonicum N1-4 in the presence of specific concentration of butyric acid (4 g L-1 butyric acid) as a co-substrate with glucose can be carried out without any remarkable inhibition to bacterial growth.