Synthesis of trimethylated phosphonium and arsonium analogues of the osmoprotectant glycine betaine; contrasted biological activities in two bacterial species

Phosphoniobetaine and arsenobetaine, the P and As analogues of glycine betaine (trimethylammonioacetate) were synthesized and assayed for activity in bacterial osmoprotection biotests, using Escherichia coli and Rhizobium meliloti as model organisms. The P- and As-betaines displayed similar osmoprotective activities in E. coli, but were highly toxic in the betaine-demethylating bacterium R. meliloti.