| 초록 |
Recently, oil-shortage and environmental pollution have caused increasing needs of producing biochemicals using non-food biomass to replace petroleum based chemicals. In this study, we produced lactic acid which is used to be a monomer for producing polylactic acids (PLA) from rice straw in Saccharomyces cerevisiae. Fermentable sugars derived from the rice straw, glucose and xylose, were prepared using the ammonia pretreatment. In addition, we constructed a S. cerevisiae harboring a plasmid containing a codon-optimized lactate dehydrogease (LDH) gene derived from Bos taurus and selected an optimal promoter to increase expression of the LDH. We produced 10.6 g/L of lactic acid and 13.0 g/L of ethanol with 40 g/L of fermentable sugars derived from the rice straw under flask fermentation. In addition, we are also constructing another lactic acid producing S. cerevisiae in which pyruvate decarboxylases (PDCs) encoding ethanol producing genes will be replaced with lactate dehydrogease (LDH) on the chromosome to increase the yield of lactic acid. This production of lactic acid with the rice straw can be applied to produce other organic acids such as 3-hydroxypropionic acid, adipic acid, succinic acid, etc, which will result in producing cost-effective biochemicals against petroleum-based chemicals. |
