(624e) Production of Optically Pure L-Lactic Acid from Paper Sludge By Bacillus Coagulans

Compare to lactobacillus, a well-known lactic acid producer, Bacillus coagulans can produce optically pure L-lactic acid at high temperature. The purity of L-lactic acid was over 99%, which is essential to make polylactic acid. The thermophilic feature of this strain makes it a good candidate to produce lactic acid because the fermentation could be performed in open condition without sterilization. In addition, it benefits the fermentation temperature to be optimum of enzymatic hydrolysis and greatly improves the fermentation efficiency. The effect of temperature, pH, and nutrient source on cell growth and fermentation was investigated. The L-lactic acid optical purity was improved as the temperature increased but higher temperature lowered the cell growth and fermentation yield. Thus, the optimal temperature was found towards the optical purity of L-lactic acid and overall fermentation performance. In the meantime, the technical feasibility of using paper sludge as feedstock to produce L-lactic acid was demonstrated.