Predation strategies of the bacterium Bdellovibrio bacteriovorus result in overexploitation and bottlenecks
Predation strategies of the bacterium Bdellovibrio bacteriovorus result in overexploitation and bottlenecks
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食菌蛭弧菌的捕食策略导致过度开发和瓶颈
DOI：
10.1101/621490
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Summers J
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文献类型：
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作者：
Summers J
随着抗菌素耐药性的增加，迫切需要用于治疗感染或去除耐药细菌的替代品，例如细菌捕食者噬菌蛭弧菌或噬菌体。因此，我们需要更好地了解微生物捕食者-猎物动力学。我们开发了大规模行动的数学模型的捕食恒化器，它捕获的低底物浓度和缓慢的增长典型的预定应用领域的捕食者，如废水处理，水产养殖，或肠道。我们的模型预测，捕食者的生存需要一个最小的猎物细胞的大小，解释了为什么蛭弧菌远小于它的猎物。被认为“太好”（攻击率太高，死亡率太低）的捕食者过度开发其猎物，导致灭绝（公地悲剧）。令人惊讶的是，一个捕食者需要更长的时间来产生更多的后代比捕食者更快地产生更少的后代（率与产量权衡）。捕食是有效的，只有在一个狭窄的区域周围的最佳参数。此外，各种条件下的极端振荡导致严重的瓶颈。当两种猎物在交替的季节出现时，这些情况就可以避免。噬菌体由于其更高的爆发大小和更快的生命周期而击败了蛭弧菌。总之，研究结果表明蛭弧菌将努力生存在一个单一的猎物，解释了为什么它必须是一个多面手捕食者，并表明它是更适合比噬菌体环境与多个prey. IMPORTANCE抗生素的发现导致了死亡人数急剧下降，由于传染病。然而，抗生素耐药性的增加有可能逆转这一进展。因此，需要替代疗法，例如基于噬菌体和捕食性细菌的疗法，这些疗法可以杀死细菌，而不管它们是病原体还是对抗生素有抗性。为了更好地利用它们，我们需要更好地了解是什么决定了它们的有效性。通过建立数学模型研究细菌在实际缓慢生长条件下的捕食行为，我们发现，对于每种猎物，通才捕食者蛭弧菌在一个狭窄的条件范围内最有效。例如，需要一个最小的猎物细胞大小，捕食者不应该“太好”，因为这将导致过度开发有灭绝的危险。这些发现共同提供了对微生物捕食生态学的见解，并有助于解释为什么蛭弧菌是一种多面手捕食者。
With increasing antimicrobial resistance, alternatives for treating infections or removing resistant bacteria are urgently needed, such as the bacterial predator Bdellovibrio bacteriovorus or bacteriophage. Therefore, we need to better understand microbial predator–prey dynamics. We developed mass-action mathematical models of predation for chemostats, which capture the low substrate concentration and slow growth typical for intended application areas of the predators such as wastewater treatment, aquaculture, or the gut. Our model predicted that predator survival required a minimal prey cell size, explaining whyBdellovibriois much smaller than its prey. A predator considered to be “too good” (attack rate too high, mortality too low) overexploited its prey, leading to extinction (tragedy of the commons). Surprisingly, a predator taking longer to produce more offspring outcompeted a predator producing fewer offspring more rapidly (rate versus yield trade-off). Predation was only efficient in a narrow region around optimal parameters. Moreover, extreme oscillations under a wide range of conditions led to severe bottlenecks. These could be avoided when two prey species became available in alternating seasons. A bacteriophage outcompetedBdellovibriodue to its higher burst size and faster life cycle. Together, results suggest thatBdellovibriowould struggle to survive on a single prey, explaining why it must be a generalist predator and suggesting it is better suited than phage to environments with multiple prey.IMPORTANCEThe discovery of antibiotics led to a dramatic drop in deaths due to infectious disease. Increasing levels of antimicrobial resistance, however, threaten to reverse this progress. There is thus a need for alternatives, such as therapies based on phage and predatory bacteria that kill bacteria regardless of whether they are pathogens or resistant to antibiotics. To best exploit them, we need to better understand what determines their effectiveness. By using a mathematical model to study bacterial predation in realistic slow growth conditions, we found that the generalist predatorBdellovibriois most effective within a narrow range of conditions for each prey. For example, a minimum prey cell size is required, and the predator should not be “too good,” as this would result in overexploitation risking extinction. Together these findings give insights into the ecology of microbial predation and help explain whyBdellovibrioneeds to be a generalist predator.