Breeding Of L-lactic Acid High-producing Strain And Optimization Of A Low-cost Media Base On Corn Steep Liquor

Lactic acid is generally recognized as one of the three organic acids。Lactic acid, lactate and its derivates have a wide range of applications in many fields such as food, medicament, chemicals etc. In the food stuff and medicine industry D and DL-lactic acid should be replaced by L-lactic acid because the human body can only metabolize L-lactic acid. Moreover, the potential use of L-lactic acid to produce poly-lactic acid for synthesis of biodegradeing plastic, makes it to have even greater potential market. Lactic acid bacteria are generally recognized as nutritionally fastidious. The complexity of the media increases the cost of lactic acid production. The cost of the fermentation medium can account for almost 30% of the total cost. Nowadays, research effort is focused on Breeding of L (+)-Lactic acid bacteria and looking for new and effective nutritional sources enabling the achievement of both high substrate conversion and high production yields.In this paper a strain of Lactobacillus rhamnosus that can produce L-lactic acid was studied。The start strain was selected by observing the color change zone. Multiple mutagenesis treatments with ultraviolet irradiation and EMS were applied and the L(+)-lactic acid producing mutant was selected based on the pathway...