Bacterial Growth and Siderophore Production in Bacteria: An Analytical Model

We have analyzed the impact of quorum sensing and resource dependency on the production of critically crucial for bacteria fitness compounds (siderophores). We have built two siderophore production models (quorum sensing and resource dependency) and linked them with Monod’s growth model. As a result, siderophore accumulation is explicitly expressed through bacterial concentration N, which allows direct experimental verification. A nutrient-dependent model predicts three siderophore accumulation phases, which accompany bacterial growth: slow accumulation for [N0, Nth], fast accumulation for [Nth, K/2], and slow or no accumulation for [K/2, K). Here N0 is the initial bacterial concentration, K is the carrying capacity. A quorum-sensing model predicts two regimes of siderophore accumulation: relatively slow accumulation for [N0, Ncr] and much faster non-linear accumulation for [Ncr, K). Ncr and Nth are model parameters. Ncr has an “absolute” value. It is dependent on bacterial strain only. Nth has a “relative” value. In addition to the bacterial strain, it also depends on inoculums concentration and the initial nutrient concentration. Such as models predict entirely different behavior, experimental data may help differentiate between these mechanisms.