Barlati S, Majerfeld I
J Bacteriol. 1970 Feb;101(2):355-60. doi: 10.1128/jb.101.2.355-360.1970.
The decline in colony-forming ability observed during tryptophan starvation of Bacillus subtilis auxotrophs is a concentration-dependent phenomenon. It does not manifest itself when the initial cell concentration is 10(6) cells/ml or lower. This property has been used to test the killing activity of different fractions of the dying cells. Most of the activity recovered is found in the supernatant fluid of the starved culture. Sensitive and resistant strains can be identified. Active supernatant fluids can only be isolated from tryptophan auxotrophs sensitive to tryptophanless death. Resistant cells neither produce nor respond to the factor, and sensitive cells respond only when deprived of tryptophan. The killing activity is continuously produced and released into the medium at least up to 4 hr after removal of tryptophan from the culture. The killing activity is deoxyribonuclease-, ribonuclease-, and heat-resistant.
枯草芽孢杆菌营养缺陷型菌株在色氨酸饥饿期间观察到的集落形成能力下降是一种浓度依赖性现象。当初始细胞浓度为10(6)个细胞/毫升或更低时，这种现象不会表现出来。这一特性已被用于测试不同部分死亡细胞的杀伤活性。回收的大部分活性物质存在于饥饿培养物的上清液中。可以鉴定出敏感菌株和抗性菌株。活性上清液只能从对无色氨酸死亡敏感的色氨酸营养缺陷型菌株中分离出来。抗性细胞既不产生也不响应该因子，而敏感细胞只有在缺乏色氨酸时才会响应。至少在从培养物中去除色氨酸后4小时内，杀伤活性持续产生并释放到培养基中。杀伤活性对脱氧核糖核酸酶、核糖核酸酶和热具有抗性。
