A 3D-printed capillary tube holder for high-throughput chemotaxis assays

Bacterial chemotaxis is an important behavior to study to understand the spatial segregation of species in mixed communities and the assembly of host microbiomes. This is particularly relevant in the rhizosphere, where chemoattraction towards root exudates is an important determinant of plant colonization. However, current methods to screen chemoeffectors are limited in their throughput, creating a barrier to generating comprehensive datasets describing chemotactic profiles for species of interest. Here, we describe a novel, 3D-printed capillary tube holder approach, which enables up to 384 simultaneous capillary tube chemotaxis assays. We optimized and benchmarked our assay using Escherichia coli k12 and Bacillus subtilis 3610 and their known chemoattractants: serine and aspartate. We then tested the threshold concentration of these chemoattractants in our assay and found we could detect chemoattraction towards concentrations spanning multiple orders of magnitude. In this paper, we describe our novel high-throughput chemotaxis assay in detail and provide the necessary files for 3D printing the capillary tube holder.

细菌趋化性（Bacterial chemotaxis）是探究混合群落内物种空间分隔与宿主微生物组组装的重要研究方向。该过程在根际（rhizosphere）环境中尤为关键：针对根系分泌物的化学吸引是决定植物定殖的核心因素之一。然而，当前用于筛选化学效应物的方法通量有限，这为获取目标物种的完整趋化谱数据集带来了阻碍。本研究提出一种新型3D打印毛细管支架方案，可同时开展至多384组毛细管趋化测定实验。我们以大肠杆菌K12（Escherichia coli K12）、枯草芽孢杆菌3610（Bacillus subtilis 3610）及其已知化学吸引剂丝氨酸（serine）、天冬氨酸（aspartate）对该实验方法进行了优化与基准测试。随后我们在该实验体系中测试了上述化学吸引剂的阈值浓度，发现本方法可检测跨度达多个数量级的浓度对应的化学吸引效应。本文详细阐述了这款新型高通量趋化测定方法，并提供了3D打印该毛细管支架所需的全部配套文件。