Experimental design for optimization of D-lactic acid production using a UV-light selected strain

Abstract

Several microorganisms have been reported to be natural D-LA producers. 15-17 Also, genetically engineered microorganisms have been reported to be pure D-LA producers. 10,12,14,18-21 However, to the best of our knowledge, it is the first time that UV-light is used as a tool to enhance D-LA production. Bearing all this in mind, the main objective of this study is to improve the D-LA production with high isomeric purity, using an isolated S_porolactobacillus nakayamae subsp. nakayamae submitted to UV-light mutation. It was also evaluated the effects of different media composition, such as different carbon and nitrogen sources on D-LA production. Methods Microorganism The microorganism S_porolactobacillus nakayamae subsp. nakayamae Vini6 is gram-positive, rod-shaped, spore-forming, and a D-LA producer. It was isolated from Desmodium adscendens root. 22 The strain was stored in GYP (Glucose-Yeast-Peptone) medium 23 with 20% glycerol (v/v) at-20°C. The microorganism was cultivated in GYP culture medium and incubated at 35°C for 24hours. Afterwards, the bacterial suspension was transferred to an Erlenmeyer flask at the same conditions and used as the inoculum. 10% of the workload was inoculated in all fermentation tests.