Interplay of motility and polymer-driven depletion forces in the initial stages of bacterial aggregation
Interplay of motility and polymer-driven depletion forces in the initial stages of bacterial aggregation
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DOI：
10.1039/c9sm00791a
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发表时间：
2019-09-21
期刊：
影响因子：
3.4
通讯作者：
Ismagilov, Rustem F.
中科院分区：
文献类型：
--
作者：
Porter, Michael K.;Steinberg, Asher Preska;Ismagilov, Rustem F.
能动细菌通常存在于复杂的、富含聚合物的环境中，其中微生物可以通过聚合物诱导的消耗力聚集。细菌聚集具有许多生物学意义;它可以促进生物膜形成，上调毒力因子，并导致群体感应。运动细菌在聚合物溶液中的稳态聚集行为已经被很好地研究，并且表明与它们的非运动类似物相比，聚集运动细菌需要更强的消耗力。然而，没有人研究过这些相同的趋势是否在聚合的初始阶段保持不变。我们使用实验和数值计算来研究聚合物诱导的运动大肠杆菌在聚乙二醇溶液中的耗尽聚集在短的实验时间尺度（类似于10分钟）。我们的工作表明，在半稀释的聚合物浓度制度，并在短时间尺度，在稳态下发现的相反，细菌的运动性实际上提高了聚集体的形成，通过增加在粘性环境中的碰撞率。这些意想不到的发现对开发活性物质模型以及了解动态生物环境中的细菌聚集具有重要意义，在动态生物环境中，系统可能永远不会达到稳态。
Motile bacteria are often found in complex, polymer-rich environments in which microbes can aggregate via polymer-induced depletion forces. Bacterial aggregation has many biological implications; it can promote biofilm formation, upregulate virulence factors, and lead to quorum sensing. The steady state aggregation behavior of motile bacteria in polymer solutions has been well studied and shows that stronger depletion forces are required to aggregate motile bacteria as compared with their nonmotile analogs. However, no one has studied whether these same trends hold at the initial stages of aggregation. We use experiments and numerical calculations to investigate the polymer-induced depletion aggregation of motile Escherichia coli in polyethylene glycol solutions on short experimental timescales (similar to 10 min). Our work reveals that in the semi-dilute polymer concentration regime and at short timescales, in contrast to what is found at steady state, bacterial motility actually enhances aggregate formation by increasing the collision rate in viscous environments. These unexpected findings have implications for developing models of active matter, and for understanding bacterial aggregation in dynamic, biological environments, where the system may never reach steady state.