Selander R K, Levin B R
Science. 1980 Oct 31;210(4469):545-7. doi: 10.1126/science.6999623.
A survey of electrophoretic variation in 20 enzymes from 109 clones of escherichia coli from natural populations yielded an estimate of mean genetic diversity approximately twice that reported in an earlier study and four to five times larger than estimates fro most eukaryotic species. Despite this extensive variability, the number of distinctive genotypes apparently is rather limited. Identical clones were obtained from unassociated hosts, and a clone that is electrophoretically indistinguishable from the laboratory strain Escherichia coli K-12 was isolated from a human infant. The results suggest that rates of genetic recombination in natural populations of Escherichia coli are low. These findings have implications for our understanding of the genetic structure of Escherichia coli populations and the factors determining the amount of neutral gene variability in this bacterial species.
对来自自然群体的109个大肠杆菌克隆体中的20种酶进行电泳变异调查，得出的平均遗传多样性估计值约为早期一项研究报告值的两倍，比大多数真核生物物种的估计值大四到五倍。尽管存在这种广泛的变异性，但独特基因型的数量显然相当有限。从无关联的宿主中获得了相同的克隆体，并且从一名人类婴儿体内分离出了一个在电泳上与实验室菌株大肠杆菌K-12无法区分的克隆体。结果表明，大肠杆菌自然群体中的基因重组率很低。这些发现对于我们理解大肠杆菌群体的遗传结构以及决定这种细菌物种中性基因变异性数量的因素具有重要意义。
