Phage-resistant bacteria reveal a role for potassium in root colonization

Abstract

Bacteriophage predation is an important factor in bacterial community dynamics and evolution. Phage-bacteria interaction has mainly been studied in lab cultures, while dynamics in natural habitats, and especially in the plant root niche are underexplored. To better understand this process, we characterized infection of the soil bacterium B. subtilis NCBI 3610 by the lytic phage SPO1 during growth in LB medium and compared it to root colonization. Resistance in vitro was primarily through modification of the phage receptor. However, this type of resistance reduced the ability to colonize the root. From a line that survived phage infection while retaining the ability to colonize the root, we identified a plant-specific phage resistance mechanism involving potassium (K+) ion influx modulation and enhanced biofilm formation.