The two types of bacteria appear to reverse their roles as predators and prey depending on temperature. Just a slight change in temperature will cause the switch to flip.
soil bacteria myxococcus xanthus They are social species that hunt in packs, forming ephemeral multicellular “swarms” that chemically tear apart and absorb nutrients from other microorganisms. And in the prey, Pseudomonas fluorescens a common bacterium in both soil and water.
Source: www.newscientist.com