L(+)-Lactic Acid Production production from glucose and Xylose with Rhizopus Oryzae Mutant RQ4015 Breeding by Low-Energy Ion Implantation

摘要

To obtain an industrial strain using glucose and xylose as carbohydrate feedstock to produce high yields of L(+)-lactic acid, a wild type strain, Rhizopus oryzae PW352, was irradiated by nitrogen ion beams. The energy of ion beams was 36 h shake-flask cultivation, the yield of L(+)-lactic acid reached 130g/l when the glucose at a concentration of 150 g/l was added as the sole carbon source in the medium..In contrast, the yield of L(+)-lactic acid from xylose at concentration of 100 g/l reached 74 g/l after 72h fermentation. In case of mixed substrates, available xylose (25g/l) and glucose (75g/l) present in Bubble column with PH4.5, the concentration of L(+)-lactic acid reached 83g. Diauxic growth was observed where consumption of glucose and xylose occurred subsequently. Sugar consumption rate and lactic acid production rate were significantly higher during glucose consumption phase compared to xylose consumption phase..