Figure 5.
D-arginine mediates interspecies altruistic cooperation within Vibrio communities. (a) Analysis of the Vibrionaceae family growth in MB medium supplemented with 10 mm D-Ala, D-Arg or D-Met. Relative OD600 is represented in gray scale. bsr: comparative genomic analysis of the presence (+) or absence (−) of BsrV homologs. nd: not determined, genome not available. Total D-amino acid content in the supernatant of overnight cultures supplemented with 5 mm L-Arg, determined by D-amino acid oxidase assay. (b) Scheme of the co-cultivation chambers used for bacterial competition assays. Compartment A is inoculated with wild-type V. cholerae, ΔbsrV mutant, a mixture or none. Compartment B is inoculated with C. crescentus. Media is supplemented or not (control) with 5 mm L-Arg. (c) Effect of D-Arg in competition assays. Upper panel: C. crescentus growth, expressed as CFU ml−1. Lower panel: total D-amino acid concentration in the supernatant, determined by D-amino acid oxidase assay.