Bacteria lower surface tension in pitcher plant traps, trapping prey more efficiently ($)

800px-darlingtonia_californica_ne9Pitcher plants are carnivorous, similar to Venus fly traps.  However, pitcher plants have fluid-filled modified leaves instead of the movable lobes found on Venus fly traps.  The pitcher plant’s modified leaf contains bacteria-laden water that traps small insects, but how are the insects trapped in the fluid?  Armitage found the bacteria lower the surface tension of the pitcher plant’s fluid to trap prey by drowning.  The author made artificial pitcher plant fluid, which had similar physical properties to natural pitcher plant fluid.  Both natural and artificial pitcher plant fluids had interfacial tension lower than pure water.  The genera of common bacteria in pitcher plant fluid, including Pseudomonas and Pedobacter, have been determined.  However, the biological mechanism for how these bacteria lower the surface tension of pitcher plant fluid remains unknown; perhaps these bacteria secrete surfactants that lower surface tension. (Review by Daniel Czerny) Biol. Lett. 10.1098/rsbl.2016.0577