Characterization and Proteomic Analysis of Geobacter sulfurreducens PCA under Long-Term Electron-Donor Starvation

The natural environment of Geobacter sulfurreducens is oligotrophic and described as limiting in both electron donors and terminal electron acceptors (TEA). In previous studies we examined the effects of long-term TEA (fumarate) limitation, and in this study we examine long-term batch cultures under limiting electron donor. The microorganism survived under long-term electron donor (acetate) starvation, maintaining a stable population of ∼1–2 × 108 cells mL−1 for >650 days. Proteins that varied in abundance with a high level of statistical significance (p G. sulfurreducens survive during starvation through detection and transport of nutrients into the cell. A sizeable portion of the identified proteins with unknown or hypothetical function further suggest that much of the biological process involved in survival have yet to be fully understood. Geobacter sulfurreducens was also able to survive under long-term TEA-starvation conditions with ferric citrate as TEA and maintained a stable population of 1.5–3 × 107 cells mL−1 for >650 days. We also found that survival phase cells from fumarate-limiting conditions were able to quickly resuscitate and reduce metal such as ferric iron as compared to the mid-log phase cells.