## 3 Results  
### The Serovars Had Similar Growth Kinetics in TSB and BPW  
Growth in TSB and BPW was measured in the strains indicated in Table 1. Growth curves over 24 h are shown in Figure 1A. Figure 1B shows the first 10 h of the total 24 h growth to highlight the lag and log phases. The data for the individual strains were grouped according to serovar. The growth curves had similar shapes to each other, and the maximum CFU/mL numbers reached were similar for the serovars in pure culture in each medium. Non-linear regression analysis was performed on the growth data, and the model revealed that the serovars grew at similar rates in both media (Table 3). The lag phase in the Enteritidis strains was longer than in the other serovars (3.0 h vs. 2.3 h). Generation times were similar in TSB and BPW at approximately 0.5 h, with serovars Enteritidis and Typhimurium growing approximately 10% faster in pure cultures. The CFU/mL counts were approximately 1 log lower in BPW, consistent with BPW being a more dilute medium than TSB.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Gene/Operon** & **Identity** & **Function** \\ \hline _phoBR_ & Two-component histidine kinase response & Respond to environmental Pi levels and transcriptional regulation of genes involved in phosphate transfer and utilization \\ _pstSCAB_ & Phosphate ABC transporter & High-affinity Pi transporter \\ _phoU_ & Phosphate-specific transport system accessory & Binds to and controls function of PstSCAB \\ _rpoS_ & Sigma factor S & Cellular responses to stresses \\ _iraP_ & RpoS adaptor protein & Inhibits RpoS proteolysis during Pi starvation \\ _rrsB_ & Adaptor protein & Regulator of RpoS degradation \\ \hline \hline \end{tabular}
\end{table}
Table 2: Genes involved in phosphate metabolism in _Salmonella_.  
Figure 1: Growth curves of the Salmonella servovars in TSB and BPW. Growth data from the Salmonella strains were averaged and are displayed according to serovar. (**A**) Log CFU/mL over 24 h; (**B**) the same graph as in (**A**) but showing only the first 10 h to highlight the lag and log phases. Enteritidis is shown with black circles, Give is shown with orange squares, Kentucky is shown with blue triangles, and Typhimurium is shown with pink diamonds. TSB curves are solid lines, and BPW curves are dashed lines.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Medium**} & \multirow{2}{*}{**Servar**} & \multicolumn{1}{c}{**Lag Phase**} & \multirow{2}{*}{**Generation**} & \multirow{2}{*}{**Maximum**} \\  & & & **Length (h)** & **Time (h)** & **CFU/mL** \\ \hline \multirow{4}{*}{TSB 1 **} & Enteritidis & 3.0 & 0.51 & \(1.32\times 10^{10}\) \\  & Give & 2.3 & 0.58 & \(2.83\times 10^{10}\) \\  & Kentucky & 2.2 & 0.56 & \(3.23\times 10^{10}\) \\  & Typhimurium & 2.2 & 0.49 & \(3.11\times 10^{10}\) \\ \hline \multirow{4}{*}{BPW 1 } & Enteritidis & 2.3 & 0.50 & \(6.69\times 10^{9}\) \\  & Give & 2.2 & 0.57 & \(6.93\times 10^{9}\) \\  & Kentucky & 2.2 & 0.57 & \(8.07\times 10^{9}\) \\  & Typhimurium & 2.3 & 0.51 & \(7.95\times 10^{9}\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Growth kinetics of _Salmonella_ serovars in TSB and BPW at 37 \({}^{\circ}\)C.