Growth advantage in stationary-phase (GASP) phenotype in long-term survival strains of Geobacter sulfurreducens

Abstract

Geobacter sulfurreducens exists in the subsurface and has been identified in sites contaminated with radioactive metals, consistent with its ability to reduce metals under anaerobic conditions. The natural state of organisms in the environment is one that lacks access to high concentrations of nutrients, namely electron donors and terminal electron acceptors (TEAs). Most studies have investigated G. sulfurreducens under high-nutrient conditions or have enriched for it in environmental systems via acetate amendments. We replicated the starvation state through long-term batch culture of G. sulfurreducens, where both electron donor and TEA were scarce. The growth curve revealed lag, log, stationary, death, and survival phases using acetate as electron donor and either fumarate or iron(III) citrate as TEA. In survival phase, G. sulfurreducens persisted at a constant cell count for as long as 23 months without replenishment of growth medium. Geobacter sulfurreducens demonstrated an ability to acquire a growth advantage in stationary-phase phenotype (GASP), with strains derived from subpopulations from death- or survival phase being able to out-compete mid-log-phase populations when co-cultured. The molecular basis for GASP was not because of any detectable mutation in the rpoS gene (GSU1525) nor because of a mutation in a putative homolog to Escherichia coli lrp, GSU3370.

Hydrogen evolution catalyzed by viable and non-viable cells on biocathodes

“…G. sulfurreducens [33] is unable to fix CO 2 , so this microorganism was unable to grow in these reactors when no organic carbon source was provided over the 5 month duration of the experiments. It is possible that some cells entered a long term survival state and remained viable, but not active [34,35]. However, tests with cell extracts makes it clear that neither active or growing cells were needed for enhanced H 2 gas production.…”

Starvation Induces Phenotypic Diversification and Convergent Evolution in Vibrio vulnificus

“…These changes were generally advantageous compared with the progenitor cells and they are referred to collectively as growth advantage in the stationary phase (GASP) phenotypes [29]. Cells that exhibit GASP phenotypes during starvation have been reported in bacteria such as Campylobacter jejuni [35], Pseudomonas [36], [37], Geobacter [38], and enterobacteria [39]. A GASP phenotype was also observed in V. fischeri [40].…”

The Cellular Chassis as the Basis for New Functionalities: Shortcomings and Requirements

“…However, ageing is sometimes positive, as can be seen in the well-described process of "growth advantage in stationary phase" (the GASP phenotype (Navarro Llorens et al 2010, 34)) a property generally foreign to standard engineering knowledge (remember the role of running in engines, however). Contrary to intuition, after mixing a population of young bacteria with an old culture, the old one outgrows the young one (Helmus et al 2012). …”