Attack or defend! A smart polymer surface has two reversibly switchable equilibrium states, a cationic N,N-dimethyl-2-morpholinone (CB-Ring) and a zwitterionic carboxy betaine (CB-OH). CB-Ring will kill bacteria upon contact under dry conditions, whereas CB-OH will release the previously attached and dead bacteria and further resist adhesion of bacteria under wet conditions.

Angriff oder Verteidigung: Die zwei schaltbaren Gleichgewichtszustände einer „intelligenten“ Polymeroberfläche, ein kationisches N,N‐Dimethyl‐2‐morpholinon (CB‐Ring) und ein zwitterionisches Carboxybetain (CB‐OH), bestimmen, ob Bakterien bei Kontakt mit der trockenen Oberfläche getötet werden (CB‐Ring) oder ob im Nassen zuvor angeheftete und tote Bakterien wieder abgelöst werden und weitere Bakterienadhäsion verhindert wird (CB‐OH).

Bradyrhizobium diazoefficiens USDA110 is one of the most effective nitrogen-fixing symbionts of soybeans. Here we carried out a large-scale transposon insertion sequencing (Tn-seq) analysis of strain Bd110spc4, which is derived from USDA110, with the goal of increasing available resources for identifying genes crucial for the survival of this plant symbiont under diverse conditions. We prepared two transposon (Tn) insertion libraries of Bd110spc4 with 155,042 unique Tn insertions when the libraries were combined, which is an average of one insertion every 58.7 bp of the reference USDA110 genome. Application of bioinformatic filtering steps to remove genes too small to be expected to have Tn insertions, resulted in a list of genes that were classified as putatively essential. Comparison of this gene set with genes putatively essential for the growth of the closely related alpha-proteobacterium, Rhodopseudomonas palustris, revealed a small set of five genes that may be collectively essential for closely related members of the family Bradyrhizobiaceae. This group includes bacteria with diverse lifestyles ranging from plant symbionts to animal-associated species to free-living species.