Efficient production of l-lactic acid from cassava powder by Lactobacillus rhamnosus

Cassava is one of the most efficient and rich crops in terms of carbohydrate production, which is a tropical perennial plant that grows on poor or depleted soils. Microbial conversion of such a renewable raw material to useful products is an important objective in industrial biotechnology. l-Lactic acid was efficiently produced from cassava powder by a Lactobacillus rhamnosus strain CASL. The fermentation properties of cassava powder were compared with those of glucose and corn powder. The efficiencies of various fermentation strategies for l-lactic acid production from cassava powder, including simultaneous saccharification and fermentation (SSF), two-step fermentation (TSF) and simultaneous liquefaction, saccharification and fermentation (SLSF), were investigated. The high l-lactic acid concentration (175.4 g/l) was obtained using 275 g/l of cassava powder concentration (total sugar of 222.5 g/l) in SSF batch fermentation. This is the highest l-lactic acid concentration reported, from cassava source, and it provides an efficient l-lactic acid production process with cheap raw bioresources, such as cassava powder.