Autoaggregation and Morphology Assay for Determining Functionality and Transport Efficiency of the Autotransporter Antigen 43 in Escherichia coli Strain DH5α

Abstract

Autoaggregation refers to the spontaneous clumping of bacterial cells, a process that can be facilitated by self-recognition structures, such as the Antigen 43 (Ag43) autotransporter, where Ag43-Ag43 interactions occur in the extracellular space to promote cell aggregation. Previous studies have highlighted key quantitative features of Ag43, including its ability to aggregate into biofilms and its role in the 'frizzy' colony morphology of Escherichia coli. The autoaggregation assay involves measuring the sedimentation rate of bacterial cells suspended in a liquid medium using a spectrophotometer to measure optical density over time. The morphology assay, performed in parallel with the aggregation assay, involves spread plating liquid culture, followed by visualization of differences in colony morphology after incubation. This methods paper presents a protocol for conducting both aggregation and morphology assays of E. coli strain DH5α to explore the functionality and transport efficiency of the Ag43 autotransporter.