Horizontal and vertical gene transfer shape the plasmid host range in surface-associated microbial systems.

Area of Science:

• Microbiology
• Genetics
• Evolutionary Biology

Background:

• Broad-host-range plasmids are key drivers of antibiotic resistance dissemination.
• Predicting plasmid host range is complex due to contributions from horizontal gene transfer (HGT) and vertical gene transfer (VGT).
• Surface-associated microbial systems are critical environments for plasmid-mediated gene spread.

Purpose of the Study:

• To investigate the interplay between HGT and VGT in determining the realized host range of broad-host-range plasmids.
• To understand how bacterial growth conditions influence transconjugant diversity and abundance.

Main Methods:

• Experimental analysis of transconjugant diversity under varying bacterial growth rates.
• Individual-based simulations incorporating both HGT and VGT dynamics.
• Assessment of plasmid spread in surface-associated microbial systems.

Main Results:

• Fast-growth conditions led to higher transconjugant abundance but lower diversity.
• Slow-growth conditions resulted in fewer transconjugants but increased diversity.
• The realized host range is a product of initial HGT events and subsequent VGT-driven expansion.

Conclusions:

• The realized host range of plasmids is jointly determined by conjugation (HGT) and proliferation (VGT).
• Bacterial growth conditions significantly modulate the balance between HGT and VGT, affecting plasmid spread dynamics.
• Accurate prediction of plasmid-mediated antibiotic resistance spread requires integrating both gene transfer and post-transfer population dynamics.