米曲霉Aspergilus oryzae发酵生产曲酸的研究

Production of Kojic Acid by Aspergillus oryzae Fementation

分离到Ａｓｐｅｒｇｉｌｕｓｏｒｙｚａｅ１３个菌株，其曲酸产量变化幅度１６６—４８６ｍｇ／ｍｌ，从中选出４个高产菌株。在１％酵母提取物和１５％蔗糖培养液中３０℃发酵培养，８—１０天菌体生长量和曲酸产量达到最大值，随后曲酸产量迅速下降。蔗糖浓度对菌体生长和曲酸产量影响甚大，最适蔗糖浓度为１５％。天冬氨酸、甘氨酸、赖氨酸、谷氨酸、吡哆醇、叶酸和抗坏血酸有利于菌体生长并显著提高曲酸产量。将在ＹＥＳ培养液中培养１０天的菌体重新悬浮于含１５％蔗糖的ＹＥＳ培养液或０２Ｍ磷酸缓冲液（ｐＨ６５）中８—１０天曲酸产量仍可达到４５ｍｇ／ｍｌ以上。低温条件下制备的培养８—１０天的Ａｏｒｙｚａｅ菌体匀浆反应系统仅有痕量曲酸形成。

13 strains of Aspergillus oryzae , isolated from air, soil, bread, cooked rice and soy sauce, were screened for their ability to produce kojic acid on a 15% sucrose and 1% yeast extract medium. The amount of kojic acid produced by different strains ranged from 16.6-48.6mg/ml. Time course producing kojic acid was studied, and the yield of kojic acid in the fermentation medium rapidly increased with the period of incubation and reached a maximum around 8-10 days after which it decreased rapidly. With sucrose as a carbon source, the best growth and yields of kojic acid were obtained at a substrate concentration of 15%, and the yield of kojic acid as per cent of sucrose added to the medium increased with sucrose concentration up to 15% followed by slight fall at the higher concentration. Aspartic acid, glycine, lysine, glutamic acid, pyridoxine, folic acid and ascorbic acid stimulated growth and raised the yield of kojic acid, and but other amino acids and vitamins were unfavorable for mycelia growth and kojic acid production. A.oryzae mycelia grown in yeast extract sucrose (YES) and resuspended in YES medium or in 0.2M phosphate buffer, pH6.5, supplemented with 15% sucrose produced kojic acid almost to the same extent as in the case of growth medium. No kojic acid was produced if buffer or media used for resuspension lacked sucrose. Only trace of kojic acid was formed in A.oryzae mycelia homogenate reaction system supplemented sucrose at 30℃ for 60min.