Carbon-Starvation Induces Cross-Resistance to Thermal, Acid, and Oxidative Stress in Serratia marcescens

Abstract

The broad host-range pathogen Serratia marcescens survives in diverse host and non-host environments, often enduring conditions in which the concentration of essential nutrients is growth-limiting. In such environments, carbon and energy source starvation (carbon-starvation) is one of the most common forms of stress encountered by S. marcescens. Related members of the family Enterobacteriaceae are known to undergo substantial changes in gene expression and physiology in response to the specific stress of carbon-starvation, enabling non-spore-forming cells to survive periods of prolonged starvation and exposure to other forms of stress (i.e., starvation-induced cross-resistance). To determine if carbon-starvation also results in elevated levels of cross-resistance in S. marcescens, both log-phase and carbon-starved cultures, depleted of glucose before the onset of high cell-density stationary-phase, were grown in minimal media at either 30 °C or 37 °C and were then challenged for resistance to high temperature (50 °C), low pH (pH 2.8), and oxidative stress (15 mM H2O2). In general, carbon-starved cells exhibited a higher level of resistance to thermal stress, acid stress, and oxidative stress compared to log-phase cells. The extent of carbon-starvation-induced cross-resistance was dependent on incubation temperature and on the particular strain of S. marcescens. In addition, strain- and temperature-dependent variations in long-term starvation survival were also observed. The enhanced stress-resistance of starved S. marcescens cells could be an important factor in their survival and persistence in many non-host environments and within certain host microenvironments where the availability of carbon sources is suboptimal for growth.

Adaptation to a limiting element involves mitigation of multiple elemental imbalances

“…Significant treatment effects on growth parameters of the ancestor indicate that the conditions were suitable for the culture of Serratia, and that the chemical manipulations of the culture medium were physiologically relevant for Serratia. Consistent with prior observations on several taxa, including Serratia [49–52], the greatest impact on yield was due to lower energy (glucose) supply, followed by lower supplies of bulk elements (N, P), while impacts of lower trace metal supplies were relatively muted (figure 1). As discussed in Warsi et al .…”

Food-Associated Stress Primes Foodborne Pathogens for the Gastrointestinal Phase of Infection

“…Another significant factor to consider with environmental induction of pathogen virulence is cross-protection, that is, resistance to multiple environmental stressors derived from bacterial exposure to a specific environmental stressor ( Capozzi et al, 2009 ; Alvarez-Ordóñez et al, 2015 , 2017 ). For example, several studies have shown that starvation stress induces heat tolerance and resistance to oxidative stress in pathogenic E. coli and Serratia marcescens ( Jenkins et al, 1988 ; Leenanon and Drake, 2001 ; Pittman et al, 2015 ).…”

Increase of Salt Tolerance in Carbon-Starved Cells of Rhodopseudomonas palustris Depending on Photosynthesis or Respiration

“…Recently, Wu et al reported the reduction of ATP levels in starved cells of mycobacteria [ 17 ]. Other studies reported that bacteria under starved conditions had increased tolerance against environmental stresses, e.g., salt, hyperosmotic pressure, desiccation, heat, and ultraviolet (UV) radiation [ 3 , 16 , 18 ]. Transcriptional factors responding to the starvation have also been extensively examined [ 19 , 20 , 21 , 22 ].…”