Selective trapping of bacteria in porous media by cell length

TL;DR

This study explores how bacterial cell length influences movement in porous environments, revealing that elongated bacteria navigate ordered pores better but are trapped in disordered media, impacting transport and separation strategies.

Contribution

It demonstrates the combined effect of cell morphology and pore architecture on bacterial motility, introducing a new approach for separating resistant bacteria based on shape.

Findings

Elongated bacteria move more efficiently in ordered pores.

In disordered media, elongated bacteria are more likely to become trapped.

Cell shape influences bacterial transport and separation in porous media.

Abstract

Bacteria commonly inhabit porous environments such as host tissues, soil, and marine sediments, where complex geometries constrain and redirect their motion. Although bacterial motility has been studied in porous media, the roles of cell length and pore shape in navigating these environments remain poorly understood. Here, we investigate how cell morphology and pore architecture jointly determine bacterial spreading behavior. Using genetically engineered E. coli with tunable cell length, we performed single-cell tracking in microfluidic devices that mimic ordered and disordered porous structures. We find that elongated bacteria traverse ordered pore networks more effectively than short cells, exhibiting straighter paths, greater directional persistence, and enhanced exploration efficiency. In contrast, in disordered porous media, elongated bacteria become trapped in dead-end regions for extended periods, resulting in markedly reduced navigational efficiency. Together, these results reveal how cell shape and environmental geometry interact to govern bacterial transport. Moreover, we suggest a new mechanism for separating antimicrobial-resistant (AMR) bacteria from elongated susceptible cells in designer porous media.