9-17: Characterization of a newly isolated Clostridium sp. strain S1 capable of producing butyric acid from galactose

Galactose is a main carbohydrate of red seaweed, which is considered as a candidate feed stock for microbial fermentation. A newly isolated bacterial strain, designated as Clostridium sp. S1, was capable of producing butyric acid from galactose as a sole carbon source. On the basis of polyphasic taxonomy, the isolate was closely related to Clostridium tyrobutyricum ATCC 25755^T (95.7%). In batch cultures, strain S1 produced 3.12 g/L of butyric acid from galactose 11.9 g/L within 3 days. When 50 mM sodium lactate and 100 mM 2-(N-morholino) ethanesulfonic acid were added simultaneously, butyric acid production was increased up to 9.52 g/L. Interestingly, in a culture of Clostridium sp. S1 in mMRS medium, only butyric acid was produced as liquid bioproducts. These results suggest that the strain S1 can be a candidate for producing butyric acid from galactose, a main hydrolysate of red seaweed.