定向筛选组氨酸营养缺陷型突变菌株的研究

STUDIES ON THE ORIENTED SCREENING OF HISTIDINE AUXPTROPHIC MUTANTS

从机理上探讨了青霉素浓缩法中关键参数确定的依据。确定饥饿培养至菌浓不再增加为止。青霉素作用前培养至细胞生长进入对数期。当 5 0 %～ 6 0 %细胞转变为原生质球时 ,停止青霉素的作用。在此条件下 ,组氨酸营养缺陷型突变菌株的获得率达 8%。

In this paper, studies were made of the determination of some key parameters in the penicillin method at the theoretical level. We optimized the conditions as followings. Starving-incubation should be processed until the population of cells begins to increase no longer. Then, before the addition of penicillin, the cells should be pre-incubated in the hypotonic medium contains 20% glucose and 0.02M MgSO 4 until the cells are in their logarithmic phrase. The most critical parameter, i.e., the duration of exposure to penicillin, could be determined by microscopic observation, and the desired time responding to a visible conversion of about 50%～60% cells to protoplasts. Under these conditions, we screened 8% histidine auxotrophic mutants on the plates.