Figure 1. P. mirabilis preferentially depletes l-serine and d-serine before other amino acids during growth in human urine.

Filter-sterilized pooled human urine from at least 20 female donors was inoculated with wild-type P. mirabilis HI4320 and incubated at 37° with aeration for 12 hours, with aliquots removed every half hour for quantification of free amino acids in cell-free supernatants by HPLC. (A and B) Data indicate the percentages of 17 amino acids after 12 hours of incubation for uninoculated urine (A) and urine inoculated with P. mirabilis (B). Categories of amino acids are color-coded as follows: polar uncharged (gray); negatively charged (blue); aromatic (green); non-polar aliphatic (orange); positively charged (red). Error bars represent mean ± standard deviation (SD) from 3 independent experiments, and dashed lines indicate 100%, 50%, and 1%. (C) Concentrations of all 12 amino acids with that were depleted at least 50% in panel B are displayed over time. Error bars represent mean ± standard deviation (SD) from 3 independent experiments. (D) Replicate supernatants from the experiment in panel C were used to determine the relative amount of each serine enantiomer over time. Data are expressed as percentage of total serine (black lines). Error bars represent mean ± SD for 3 independent experiments with 3 technical replicates each.