Isolation of a Highly Tolerant Lactic Acid Bacterium and HighTiter L-Lactic Acid Fermentation Using Lignocellulosic Feedstock

Production of Llactic acid from abundant lignocellulosic resource has become an important trend for research and commercialization because polylactic acid (PLA) from Llactic acid is regarded as the next generation biodegradable plastic. A highly tolerant lactic acid bacterium (LAB) was isolated from the cellulosic ethanol fermentation broth at elevated temperature and identified as Pediococcus acidilactici using 16S rDNA and phylogenic analysis. P. acidilactici DQ2 is high thermotolerance and high resistance to the lignocellulose derived inhibitors. These characteristics probably are associated with environmental mutation and stimulating factors naturally present in the lignocellulosic hydrolysate system. The titer and yield of Llactic acid in the simultaneous saccharification and fermentation (SSF) using the diluted acid pretreated corn stover (CS) were 75 g/L and 0.63 g/g cellulose, respectively, and showed a great potential for cellulosic lactic acid production for the future commercial application.