FIG 1.
Putrescine is an essential nutrient source during B. abortus growth in vitro. (A) Schematic representation of differences in polyamine synthesis between S. Typhimurium and B. abortus based on Kusano and Suzuki (44) and the most-recent genomic and metabolomic data available in the MetaCyc/BioCyc (45) and KEGG (46) databases. (B) Fold growth of of B. abortus 2308 (wild type [WT]) in modified F12/k medium with and without putrescine as well as the potIHGF mutant (TOK13) at 24 h postinoculation. The inoculum was 0.5 × 105 CFU/ml. Bars represent geometric means, and circles represent results of independent replicates. The statistical significance of differences between groups was determined using a one-way ANOVA with the Sidak multiple-comparison test. Asterisks denote statistically significant differences between groups (P < 0.05); ns, not significant.