Using experimental evolution to explore natural patterns between bacterial motility and resistance to bacteriophages

Area of Science:

• Microbiology
• Evolutionary Biology
• Bacteriology

Background:

• Bacterial resistance to phages (bacteriophages) often involves changes to surface proteins.
• These surface proteins are crucial for bacterial functions like motility and nutrient uptake, suggesting a potential fitness cost to resistance.
• Understanding this potential trade-off is key to comprehending bacterial evolution and phage-host dynamics.

Purpose of the Study:

• To investigate the potential evolutionary trade-off between bacterial phage resistance and bacterial motility/growth rate.
• To determine if acquiring resistance to phages causally impacts bacterial fitness traits.

Main Methods:

• Systematic study of 80 natural bacterial isolates from horse chestnut leaves and their associated phages.
• Comparative analysis of bacterial motility, growth rate, and phage susceptibility.
• Experimental evolution of bacterial populations in the presence and absence of phages to test for causal links.

Main Results:

• No negative association was observed between natural phage resistance and bacterial motility or growth rate in the studied populations.
• Experimental evolution did not reveal a clear link between the acquisition of phage resistance and changes in bacterial motility.
• The findings contradict the expectation of a significant fitness cost associated with phage resistance.

Conclusions:

• Phage-mediated selection is unlikely to shape bacterial motility in these natural phyllosphere populations.
• The absence of a trade-off suggests that bacteria can evolve phage resistance without compromising essential fitness traits.
• The combined correlational and experimental approach effectively tested evolutionary trade-off hypotheses.