Production of biosolvents and acids by salinity-adapted strain of clostridium acetobutylicum: Effects of salt and molasses concentrations

Abstract

In this study, the growth of Clostridium acetobutylicum was evaluated in Clostridium basal medium (CBM) containing 0.001, 0.5, 1, 2 and 4 % salt concentrations. Although the strain is sensitive to salinity of more than 2 %, the adapted strain was shown to grow even at 6 % salinity. Results indicate adverse effects of salinity on bacterial growth and bioproducts, such as 1- -butanol and butyric acid, whereas the produced acetone is increased by salinity in CBM. In addition, the glucose of CBM is substituted by sugar beet molasses, due to its lower price and greater accessibility. Therefore, molasses-based mediums (MBM) at different concentrations of molasses were examined to assess the effect of molasses concentration on the adapted strain at low salinity. The results showed that 4 and 6 % concentrations of molasses are optimum concentrations for bacterial growth and its production of bioproducts at low salinity. Finally, the simultaneous effects of salinity and molasses concentration on the adapted strain were investigated. For this purpose, molasses-based mediums (MBM) containing 2, 3 and 4 % molasses concentration at 4 % salinity were considered. The results demonstrated that the increase in the molasses concentration raises the production of both butyric acid and acetone.