## 1 Introduction  
For many years, the Gram-negative bacterium _Serratia marcescens_ was regarded as a generally harmless, saprophytic microorganism [1]. More recently, we have come to understand that _S. marcescens_ is an emerging, broad host-range, opportunistic pathogen of growing importance [1; 2; 3; 4]. Depending on the strain, _S. marcescens_ can harbor genetic elements encoding virulence factors and antibiotic resistance determinants [5; 6]. Reservoirs and sources of human infection frequently include nutrient-poor environments, such as saline solutions and contact lens solutions [7; 8]. Starvation is the normal state of affairs for bacteria in such environments, and physiological mechanisms for coping with starvation stress are essential for bacterial survival under these conditions. In other closely related members of the family _Enterobacteriaceae_, such as _Escherichia coli_ and _Salmonella enterica_, starvation stress is known to trigger a global change in gene expression and cellular physiology referred to as the starvation-stress response or SSR [9; 10; 11]. The response to carbon and energy starvation (carbon-starvation) is especially complex and involves induction of a network of genes ultimately leading to a distinctly different type of cell, the carbon-starved cell. In addition to being able to survive prolonged periods of carbon-starvation, starved cells develop cross-resistance toward a number of other environmental stresses including temperature stress, pH stress, and oxidative stress. Surprisingly little is known about the effects of starvation stress on _S. marcescens_ despite potential connections to environmental survival and pathogenesis. Environmental strains of _S. marcescens_, such as those isolated from soil and bodies of water, grow to form pink to red colored colonies on solid media due to the production of the pigment prodigiosin, while strains isolated from clinical specimens tend to be non-pigmented [12; 13; 14]. In addition, some strains produce less pigment when grown at temperatures above 25 \({}^{\circ}\)C-30 \({}^{\circ}\)C. When streaked onto rich agar media and incubated at room temperature, the type strain _Serratia marcescens_ subsp. _marcescens_ Bizio ATCC 13880, grows to form a mixture of pigmented, non-pigmented, and partially pigmented colonies. However, the differences between _S. marcescens_ isolates are not limited to pigmentation. For example, temperature-dependent variations in metabolism, virulence, and antimicrobial resistance have also been observed [6; 14; 15; 16; 17; 18; 19; 20]. _S. marcescens_ is notorious for surviving on moist surfaces, in nutrient-poor aqueous environments, and in solutions containing powerful disinfectants [21; 22; 23; 24; 25; 26; 27]. In many of these situations, bacterial cells have to adapt to carbon-source availability. In a nosocomial setting, stress-resistant carbon-starved cells surviving on or in fomites are likely to be a source of infection, especially for immunosuppressed or immunocompromised patients. Once inside the human or animal host, phagocytic cells of the immune system may have difficulty in destroying stress-resistant carbon-starved cells [10; 11; 28]. Therefore, the physiological response to carbon-starvation is an important aspect of _S. marcescens_ environmental survival and pathogenesis. Elevated temperatures, acidic conditions, and exposure to oxidizing chemicals are also forms of stress _S. marcescens_ confronts during passage through host and non-host environments, and any increase in the resistance of carbon-starved cells to these forms of stress (_i.e._, starvation-induced cross-resistance) would influence the survival and spread of _S. marcescens_ as well. It is conceivable that _S. marcescens_ encounters these potentially lethal stresses during various cleaning practices, during certain medical procedures, during a high fever, during passage through stomach acid, or while in the hostile microenvironment of the phagolysosome. In this study we performed a series of experiments designed to determine if _S.