Cooney P H, Whiteman P F, Freese E
J Bacteriol. 1977 Feb;129(2):901-7. doi: 10.1128/jb.129.2.901-907.1977.
At some time during sporulation development, cells of Bacillus subtilis develop a commitment to continue sporulation even after addition of or dilution into a fresh nutrient. The extent of commitment was measured by the titer of spores produced at the time at which the original culture sporulated maximally. Since newly formed spores of B. subtilis soon germinate in the replenished medium, the measurement of their titer, especially of heat-resistant spores, gave low values. This problem was avoided by the germination-delaying effect of methyl anthranilate (1 mM) when added together with the fresh nutrients. In a given culture, the titer of committed cells was then independent of the method by which it was measured, i.e., by the phase-bright, octanol-resistant, or heat-resistant spore titer. The time of commitment depended on the type of nutrient added. Commitment occurred earlor casein hydrolysate. The rates at which non-metabolizable amino acid analogues or the 14C from an amino acid mixture were taken up by the cells increased toward the end of growth and later declined. This decline occurred slowly and was only weakly correlated with the commitment time of an analogous amino acid.
在芽孢形成发育的某个阶段，枯草芽孢杆菌的细胞即使在添加新鲜营养物质或稀释到新鲜营养物质中后，也会产生继续进行芽孢形成的倾向。通过在原始培养物最大程度地形成芽孢时所产生的芽孢滴度来衡量这种倾向的程度。由于枯草芽孢杆菌新形成的芽孢很快会在补充培养基中萌发，所以对其滴度的测量，尤其是对耐热芽孢滴度的测量，得到的值较低。当与新鲜营养物质一起添加时，邻氨基苯甲酸甲酯（1 mM）的萌发延迟效应避免了这个问题。在给定的培养物中，处于倾向状态的细胞滴度与测量方法无关，即与明亮相、耐辛醇或耐热芽孢滴度无关。倾向发生的时间取决于添加的营养物质类型。在添加酪蛋白水解物的情况下，倾向发生得更早。细胞对不可代谢的氨基酸类似物或氨基酸混合物中14C的摄取速率在生长末期增加，随后下降。这种下降发生得很缓慢，并且与类似氨基酸的倾向时间只有微弱的相关性。
