The New Technology Of Fermentation And In Situ Product Removal For Lactic Acid Production

In this paper, the breeding of lactic acid-resistant stains, culture condition on the fermentation and In Situ product removal of lactic acid production was studied. The most lactic acid-resistant strain Lactobacillus delbrueckii YJS-2 was selected from three original L. delbrueckii YJS- 1, YJS-2, YJS-3. L.delbrueckii YJS-2 could breed on the medium with the concentra-tion of lactic acid 16g/L. By means of U.V irradiation, L.delbrueckii YJS-2-1 was obtained on the lactic acid and glucose medium with lactic acid 22g/L and glucose 1 60g/L respectively. By means of conventional batch fermentation, auxotroph of L.delbrueckii YJS-2-1 was studied. The result showed that L.delbrueckii YJS-2-1 was unable to synthesized L-glutamic acid, L-aspartic acid, L-tryptophan, L-isoleucine, Biotin, p-aminobenzoic acid and thiamine-HC1 accelerated reproduction of the stain and im-proved the yield of lactic acid. Meanwhile, the fermentation medium was optimized. A maximum yield was obtained under the following conditions: rice starch saccharification of 1 50g/L, L-glutamic acid 3Omg/L, L-aspartic acid O.88rng/L, L-tryptophan 1 .2mg/L, L-isoleucine 1 .2mg/L, biotin 1 80[tg/L, thiamine-HC1 4mg/L, p-aminobenzoicacid 2Omg/L. On lactic acid optimum batch fermentation, the yield of 140.3g/L lactic acid, sucrose conversion of 93.5%, productivity of 1.9SgLh was obtained. Bran could be substituted. The characteristic of anion-exchange resin was studied. It showed that the D408 anion-exchange resin few was damaged, decolored, absorbed glucose and pigment, etc. At the same time, D408 didn effect the cell growth. Glucose and cell in the medium did not effected exchangeable amount of Lactic acid. The D408 anion-exchange resin could be used to adsorb lactic acid. The In Situ product removal batch-wise fermentation with D408anion-exchange resin were studied. The optimum conditions were ascertained. The maximum yield was obtain under the following conditions: glucose of 1 5OgIL, exacting when the concentration of lactic acid was 1 Og/L, the broth of 80% via resin column, supplying glucose, supplying the cell of 6%. Under the optimum technics condition, the reclaiming rate of 91.8%, productivity of 2.1 5g.UW biomass of 30. lg/L was obtained. The new technology reduced time to 64 hours and was evidently better than the now technology.