Dykes G A, Hastings J W
Department of Genetics, University of Natal, Scottsville, South Africa.
Proc Biol Sci. 1997 May 22;264(1382):683-7. doi: 10.1098/rspb.1997.0097.
Bacteriocins are proteinaceous anticompetitor molecules produced by bacteria against closely related species. A number of theoretical models have been used to explain experimental data that indicate high polymorphisms among bacteriocins and a frequency-dependent nature of selection for bacteriocin-producing strains. The majority of these experimental data were, however, obtained from investigations into the colicin group of bacteriocins produced by Gram-negative bacteria. The conclusions drawn from these models have been extrapolated to other bacteriocins and allelopathic compounds in general. Examination of more recent experimental investigations into the bacteriocins of Gram-positive bacteria indicate a lower degree of polymorphism and a less frequency dependent mode of selection among these strains them among the colicin-producing strains. Here we examine these contradictions in the light of the assumptions and conclusions of the theoretical models and reported data. We show that fitness costs as indicated by decreased relative maximum growth rate associated with bacteriocin production may be much lower in many cases than is assumed in the present models. A lower fitness cost associated with bacteriocin production adequately explains the newer data from Gram-positive bacteria cited here, and indicates that extrapolation of existing models to all bacteriocins and other allelopathic compounds is not appropriate.
细菌素是细菌产生的针对密切相关物种的蛋白质类抗竞争分子。许多理论模型已被用于解释实验数据，这些数据表明细菌素之间存在高度多态性，以及产生细菌素的菌株的选择具有频率依赖性。然而，这些实验数据大多来自对革兰氏阴性菌产生的大肠杆菌素类细菌素的研究。从这些模型得出的结论已被外推到其他细菌素和一般化感物质。对革兰氏阳性菌细菌素的最新实验研究表明，这些菌株之间的多态性程度较低，选择模式的频率依赖性也低于产生大肠杆菌素的菌株。在这里，我们根据理论模型的假设和结论以及报告的数据来审视这些矛盾。我们表明，与细菌素产生相关的相对最大生长速率降低所表明的适应性成本在许多情况下可能比当前模型所假设的要低得多。与细菌素产生相关的较低适应性成本充分解释了此处引用的革兰氏阳性菌的新数据，并表明将现有模型外推到所有细菌素和其他化感物质是不合适的。
