Bacteria form colonies and secrete extracellular polymeric substances that surround the individual cells. These spatial structures are often associated with collaboration and quorum sensing between the bacteria. Here we investigate the mutual protection provided by spherical growth of a monoclonal colony during exposure to phages that proliferate on its surface. As a proof of concept we exposed growing colonies of Escherichia coli to a virulent mutant of phage P1. When the colony consists of less than <mml:math><mml:mo>∼</mml:mo></mml:math>∼50,000 members it is eliminated, while larger initial colonies allow long-term survival of both phage-resistant mutants and, importantly, colonies of mostly phage-sensitive members. A mathematical model predicts that colonies formed solely by phage-sensitive bacteria can survive because the growth of bacteria throughout the colony exceeds the killing of bacteria on the surface and pinpoints how the critical colony size depends on key parameters in the phage infection cycle.

中文翻译：

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不断增长的小菌落可以生存并支持有毒噬菌体的持续繁殖

细菌形成菌落并分泌围绕单个细胞的细胞外聚合物。这些空间结构通常与细菌之间的协作和群体感应相关。在这里，我们研究了在暴露于其表面增殖的噬菌体期间，单克隆菌落的球形生长所提供的相互保护。作为概念验证，我们将大肠杆菌的生长菌落暴露于噬菌体P1的强毒突变体。当菌落组成少于<mml:math><mml:mo>∼</mml:mo></mml:math>〜消除了50,000个成员，而较大的初始菌落则可以使两个噬菌体抗性突变体以及大多数为噬菌体敏感成员的菌落长期存活。数学模型预测，仅由噬菌体敏感性细菌形成的菌落可以生存，因为整个菌落中细菌的生长超过了表面细菌的杀灭力，并指出了关键菌落的大小如何取决于噬菌体感染周期中的关键参数。