Universality of shear dependence of conjugation rates across species and plasmids

Establish whether the shear-dependent conjugation-rate relationship observed for Escherichia coli carrying IncF plasmids R1-19 and F in a cone-and-plate rheometer holds universally across diverse bacterial species and plasmid types, including those that produce short, rigid pili or require surfaces for efficient conjugation.

Background

The paper quantified how controlled shear flow modulates conjugation rates between E. coli donors and recipients carrying IncF plasmids (R1-19 and F), revealing a shared functional dependence on shear rate with a peak near 10^2 s^-1. Despite this similarity after rescaling absolute rates, the authors note that plasmids differ by pili type (e.g., long, flexible retractable pili in IncF versus short, rigid pili in IncW/IncP) and by their dependence on surfaces for mating.

Given these biological differences, it is unclear whether the observed shear–conjugation relationship generalizes beyond the specific strains and plasmids tested. Determining universality (or its limits) would clarify how environmental flows impact horizontal gene transfer across microbial diversity.