Guseva Ksenia, Feudel Ulrike
Centre for Microbiology and Environmental Systems Science, University of Vienna, Wien, Austria.
Carl von Ossietzky University of Oldenburg, Oldenburg, Germany.
J R Soc Interface. 2025 Jun;22(227):20250037. doi: 10.1098/rsif.2025.0037. Epub 2025 Jun 18.
Marine bacteria are fundamental to the processes and cycles that sustain ocean ecosystems. Their activity at small scales, where they search for food sources in a highly heterogeneous and dynamic environment, for example controls the decomposition of organic matter. To be effective, these microorganisms have evolved sophisticated behaviours, which include extremely rapid swimming speeds, a precise chemosensing ability and particular swimming patterns. One of these peculiar motility patterns often recorded in the ocean is run-reverse (Mitchell 1996 Clustering of marine bacteria in seawater enrichments. , 3716-3721. (doi:10.1128/aem.62.10.3716-3721.1996), Stocker R. 2011 Reverse and flick: hybrid locomotion in bacteria. , 2635-2636. (doi:10.1073/pnas.1019199108), where bacteria alternate between forward (pushing) and backwards (pulling) swimming modes. In this study, we investigate whether this swimming pattern offers advantages to microorganisms that actively track small and light food sources carried by a dynamic flow. For that we develop an individual-based model, where elongated self-propelled particles (microswimmers) track passive food particles (tracers) in a random kinematic flow field, also known as synthetic turbulent flow. We compare the widely studied motility pattern of run-and-tumble with the run-reverse mode used by marine bacteria. Our results reveal a significant hydrodynamic advantage of the run-reverse motility pattern of bacteria combined with their elongated shapes for efficiently tracking light food sources in dynamic fluid environments.
海洋细菌对于维持海洋生态系统的过程和循环至关重要。例如，它们在小尺度上的活动，即在高度异质和动态的环境中寻找食物来源，控制着有机物的分解。为了高效运作，这些微生物进化出了复杂的行为，包括极快的游动速度、精确的化学感应能力和特定的游动模式。在海洋中经常记录到的一种特殊运动模式是“游动-反转”模式（米切尔，1996年，《海水中富集的海洋细菌的聚集》，第3716 - 3721页。（doi:10.1128/aem.62.10.3716 - 3721.1996），斯托克，R. 2011年，《反转和轻弹：细菌中的混合运动》，第2635 - 2636页。（doi:10.1073/pnas.1019199108）），即细菌在向前（推进）和向后（拉动）游动模式之间交替。在本研究中，我们探究这种游动模式是否为积极追踪动态水流携带的微小轻质食物来源的微生物提供优势。为此，我们开发了一个基于个体的模型，其中细长的自推进粒子（微型游动者）在随机运动流场（也称为合成湍流）中追踪被动食物粒子（示踪剂）。我们将广泛研究的“游动-翻滚”运动模式与海洋细菌使用的“游动-反转”模式进行比较。我们的结果揭示了细菌的“游动-反转”运动模式及其细长形状在动态流体环境中有效追踪轻质食物来源方面具有显著的流体动力学优势。
