| 摘要 |
PURPOSE:To easily obtain D-lactic acid having high optical purify, by culturing a microbial strain assimilating L-lactic acid in a medium containing racemic lactic acid or a mixture of the recemic compound and an optically active lactic acid or by contacting the racemic lactic acid, etc., with cultured microorganism. CONSTITUTION:A culture medium is prepared by using racemic lactic acid or a mixture of racemic lactic acid and an optically active lactic acid as a carbon source and compounding the source with a nitrogen source such as urea, inorganic salt such as MgSO4 and, if necessary, a proliferation promoting factor such as yeast extract. The obtained medium is inoculated with a microbial strain (e.g. Bacillus subtilis IFO 3134) belonging to Bacillus genus and having an assimilation rate of L-lactic acid high than that of D-lactic acid. The strain is cultured in the medium at 3-10pH and 20-60 deg.C for several hours several days under supply of air. The microbial cells are separated and removed from the cultured product and the supernatant liquid is concentrated and refined by ion exchange treatment, solvent extraction, etc., to obtain the objective D-lactic acid. |
