赭曲霉转化甾体过程中色素的分析和控制

THE ANALYSIS AND CONTROL OF PIGMENT PRODUCED IN STEROID BIOCONVERSION BY ASPERRGILLUS OCHRACEUS

通过对甾体Ｃ(１１)α羟基化菌株赭曲霉发酵液中色素的分离纯化，得到一种砖红色的色素。经紫外－可见分光光度法、红外光谱法和核磁共振谱图分析，证明该色素为苯醌类色素，与初级代谢过程中的芳香族氨基酸有相同的代谢途径，利用芳香族氨基酸的代谢模式，在加有２％沃氏氧化物的发酵体系中添加５ｍｍｏｌ／Ｌ的色氨酸，或５ｍｍｏｌ／Ｌ等体积的苯丙氨酸和酪氨酸混合液，均能明显抑制发酵过程中色素的产生，提高产物的收率。同时通过诱变选育的莽草酸缺陷型菌株发酵后，甾体转化力均有所下降，但发酵液不再产生砖红色色素，进一步选育的抗碘乙酸突变株使甾体的转化率又恢复到原有水平。

One orange-red pigment was purified from fermentation solution of steroid C_(11)-α hydroxylgenation by Aspergillus ochraceus. The spectrum of UV-VIS, IR and NMR show that the pigment belongs to the kind of benzquinione compound. The metabolic pathway of the pigment is the same as aromatic amino acids. According to the metabolic model of aromatic acids, tryptophane of 5mmol/ L or the mixed phenylalanine and tyrosine (at same volume) of 5mmol / L was added in fermentation solution containing 2% 16α, 17α-epoxy-4-pregene-3,20-dione, the production of pigment could be inhibited in the process of steroid conversion obviously. The shikimic acid auxotrophs derived by mutating original Aspergillus ochraceus were used to convert steroid. C_(11)α-hydroxygenation activity of mutants decrease, but fermentation solution have not orange-red pigment. Then the auxotroph was mutated by UV-ray, one AcI-resistance strain with original conversion ratio was obtained.