Boe L, Tolker-Nielsen T, Eegholm K M, Spliid H, Vrang A
Department of Microbiology, Technical University of Denmark, Lyngby.
J Bacteriol. 1994 May;176(10):2781-7. doi: 10.1128/jb.176.10.2781-2787.1994.
Mutations of Escherichia coli from sensitivity to nalidixic acid resistance were studied by fluctuation analysis. The mutant distributions in replicate cultures were not significantly affected either by the age of the carbon-starved preculture used for inocula or by the inoculum size. The data from 23 fluctuation tests (48 cultures each) were pooled. The mean number of mutations per culture was estimated to be 0.71 from the fraction of cultures without mutants or 0.74 and 0.77 by maximum-likelihood estimation based on the two models under consideration. When the pooled data were compared with the theoretical expectations, the fits were unsatisfactory (P < 0.005). The lack of fit was caused mainly by too high a frequency of cultures with between 17 and 32 mutants and too high a frequency of cultures with more than 128 mutants. Possible reasons for the lack of fit and its implications with respect to estimation of mutation rates from fluctuation tests are discussed.
通过波动分析研究了大肠杆菌从对萘啶酸敏感突变为耐药的情况。用于接种的碳饥饿预培养物的年龄或接种量对重复培养物中的突变体分布均无显著影响。汇总了23次波动试验（每次48个培养物）的数据。根据无突变体的培养物比例估计，每个培养物的平均突变数为0.71，基于所考虑的两个模型通过最大似然估计为0.74和0.77。当将汇总数据与理论预期进行比较时，拟合效果不理想（P < 0.005）。拟合不佳主要是由于具有17至32个突变体的培养物频率过高以及具有超过128个突变体的培养物频率过高。讨论了拟合不佳的可能原因及其对从波动试验估计突变率的影响。
