Bacterial communities are governed by a wide variety of social interactions, some of which are antagonistic with potential significance for bacterial warfare. Several antagonistic mechanisms, such as killing via the type VI secretion system (T6SS), require killer cells to directly contact target cells. The T6SS is hypothesized to be a highly potent weapon, capable of facilitating the invasion and defence of bacterial populations. However, we find that the efficacy of contact killing is severely limited by the material consequences of cell death. Through experiments with Vibrio cholerae strains that kill via the T6SS, we show that dead cell debris quickly accumulates at the interface that forms between competing strains, preventing physical contact and thus preventing killing. While previous experiments have shown that T6SS killing can reduce a population of target cells by as much as 106-fold, we find that, as a result of the formation of dead cell debris barriers, the impact of contact killing depends sensitively on the initial concentration of killer cells. Killer cells are incapable of invading or eliminating competitors on a community level. Instead, bacterial warfare itself can facilitate coexistence between nominally antagonistic strains. While a variety of defensive strategies against microbial warfare exist, the material consequences of cell death provide target cells with their first line of defence.

中文翻译：

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接触杀伤引起的死亡细胞的积累促进细菌生物膜中的共存


细菌群落受到多种社会互动的控制，其中一些是对抗性的，对细菌战具有潜在的意义。多种拮抗机制，例如通过 VI 型分泌系统 (T6SS) 进行杀伤，需要杀伤细胞直接接触靶细胞。 T6SS 被认为是一种高效武器，能够促进细菌群体的入侵和防御。然而，我们发现接触杀伤的功效受到细胞死亡的物质后果的严重限制。通过对通过 T6SS 杀死的霍乱弧菌菌株进行的实验，我们发现死细胞碎片会在竞争菌株之间形成的界面上迅速积聚，从而阻止物理接触，从而防止杀死。虽然之前的实验表明 T6SS 杀伤可以使靶细胞数量减少多达 106 倍，但我们发现，由于死细胞碎片屏障的形成，接触杀伤的影响敏感地取决于初始浓度杀伤细胞。杀伤细胞无法在群落层面上入侵或消灭竞争对手。相反，细菌战本身可以促进名义上拮抗菌株之间的共存。虽然存在多种针对微生物战的防御策略，但细胞死亡的物质后果为靶细胞提供了第一道防线。