Survival of <i>Escherichia coli</i> under Nutrient-Deprived Conditions: Effect on Cell Envelope Subproteome

Abstract

In the aquatic ecosystems, microorganisms are exposed to seasonal and circadian cycles. Abiotic factors (e.g. low temperature, nutrient deprivation) can cause morphological and physiological changes in bacteria, thereby facilitating cell survival. While representing the interface between the cells and external environment, the cell envelope plays a major role in bacterial response to stress and characterization of the changes it undergoes can help to understand the adaptation process. In this study, analysis of the morphological and physiological changes as well as variations in protein composition of the Escherichia coli cell envelope was carried out for populations maintained for 21 days under nutrient deprivation and suboptimal temperatures (4°C and 20°C). It was found that the absence of nutrients led to a temperature-dependent reduction of cell culturability but had no effect on cell viability and integrity. The concentration of membrane proteins playing the key roles in cellular transport, maintenance of cell structure or bioenergetics processes remained mainly unchanged. In contrast, the level of several proteins such as the elongation factor EFTu 1, components of Bam complex or proteins implicated in chemotaxis was altered, thus indicating that cells were readily responding and adapting to stress.

Energy dependence of signalling dynamics and robustness in bacterial two component systems

“…That is, when ATP levels are low, we interpret this as the bacteria being starved of a food source. Even in starvation or hostile conditions, cells can still continue to operate as normal [29].…”

“…A signal that is too weak to be detected may result in a false negative stimulus detection. This may not be detrimental in some cases, as the activities of the TCSs in a cell could be triaged according to need (for example, TCSs related to cell structure or metabolism may be prioritised [29]).…”

“…This response behaviour could be useful for a system which triggers energy-intensive operations within the cell. Bacteria have been shown to adjust protein abundance in starvation or other hostile conditions [29]. In low energy environments, where food is scarce or energy must be rationed carefully, a cell may not want to waste energy following a false positive signal for food.…”

Profiling Mycobacterium Ulcerans : Sporulation, Survival Strategy and Response to Environmental Factors

“…The long-chain fatty acids are essential for its metabolic activities, and glycerol serves as a carbon source. In hostile environments such as nutrient limitations and extreme temperature, bacteria engage adaptive survival mechanisms [ 51 ]. For example, Vibrio cholerae exist in a viable, nonculturable state upon nutrient deprivation [ 52 ].…”

“…For example, Vibrio cholerae exist in a viable, nonculturable state upon nutrient deprivation [ 52 ]. Nutrient deprivation in Escherichia coli has no effect on cell viability and integrity, however it induces a temperature dependent reduction in cell-culturability [ 51 ]. In S. aureus , multiple-nutrient (glucose, amino acid and phosphate) starvation results in a loss of viability, decrease in cell size and increased resistance to acid shock and oxidative stress [ 53 ].…”