Production of D-lactic acid and L-lactic acid from regeneratedresources by Lactobacillus pentosus and characterization ofD-LDH and L-LDH gene.

• Main Authors: Yu-Shiou Luo, 羅毓秀
• Other Authors: Fu-Shyan Wen
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/58145246363637597715

碩士 === 國立中興大學 === 生命科學系 === 93 === Lactic acid and its derivative are used for many applications suck like food, medicine, chemical industry, leather and biodegradable plastic. Lactic acid is mainly produced through fermentation processes. Polylactic acid (PLA) is being developed as a renewable alternative for conventional petroleum-based plastics. That can be lost all mechanical properties when composted for five weeks. PLA can be tailored to specific applications by altering the ratio of the L- lactic acid and D-lactic acid isomers. The annual requirement of international market increases at the speed of 10%-20%. Global lactic acid demand was around 400,000 tons, but the amount of production was 250,000 tons. Lactic acid is ferment from agricultural crops by lactic acid bacteria. Lactobacillus pentosus is a homofermenative lactic acid bacterial with the capacity to produce high level of D-lactic acid and L-lactic acid. In this study, production of D-lactic acid and L-lactic acid from regenerated resources, sewage sludge and waste cola, by L. pentosus. In order to achieve the objective of sustainable development, we should place emphasis on the economical resource, reduce the emission of waste and make use of discarded or trashed materials. D-lactate dehydrogenase and L-lactate dehydrogenase convert pyruvate into D-lactic acid and L-lactic acid, respectively. The study uses molecular technology to finish the whole d-ldh and l-ldh gene sequence and tries to express the whole d-ldh or l-ldh gene into E. coli BL21(DE3) to product D-lactic acid and L-lactic acid. The study also clones many vector and transpormation the vector into L. pentosus by electroporation. Hope the d-ldh or l-ldh gene on chromosome DNA is destructed by homologus recombination and by this way to production single form lactic acid but it hasn’t succeed so far.