Studies of long-term stationary phase growth and survival of E. coli led to the discovery of the growth advantage in stationary phase or GASP phenotype, which reflects the Ku-0059436 research buy ability of bacteria from an aged culture to outcompete the same strain of bacteria from a younger culture when the two are grown together (Zambrano et al., 1993). For E. coli grown in LB, the aged culture must be at least 8 days old and in the long-term stationary phase of growth to effectively

outcompete a younger 1-day-old culture (Zambrano & Kolter, 1993; Zambrano et al., 1993; Finkel, 2006). The GASP phenotype of E. coli results from a dynamic and continuous acquisition of mutations that increase bacterial fitness during periods of long-term stationary growth (Zambrano & Kolter, 1993; Zambrano et al., 1993; Zinser & Kolter, 1999, 2000, 2004; Farrell & Finkel, 2003; Zinser et al., 2003). Listeria monocytogenes Seliciclib research buy is a Gram-positive environmental bacterial pathogen that has evolved to survive in disparate environments both inside and

outside mammalian hosts (Vazquez-Boland et al., 2001; Czuprynski, 2005; Gray et al., 2006). As an intracellular pathogen, the bacterium invades mammalian cells, escapes from host cell phagosomes, replicates within the cytosol, and spreads into neighboring cells (Hamon et al., 2006; Freitag et al., 2009). A number of bacterial factors are required for L. monocytogenes intracellular replication and cell-to-cell spread (Goebel et al., 2000; Vazquez-Boland et al., 2001), and the expression of a majority of these gene products is regulated by the transcriptional regulator known as PrfA (Kreft & Vazquez-Boland, 2001; Scortti et al., 2007). The fitness of L. monocytogenes inside the host Loperamide is severely compromised in the absence of PrfA (Freitag, 2006). Outside the mammalian hosts, L. monocytogenes is widely distributed and is believed to live as

a saprophyte of decaying plant material (Gray & Killinger, 1966; Vazquez-Boland et al., 2001; Czuprynski, 2005; Freitag et al., 2009). Listeria monocytogenes has been isolated from soil, silage, ground water, sewage, and vegetation (Thevenot et al., 2006) and, although it does not form spores, the bacterium can become firmly established in food processing environments and persist for long periods of time, even for years (Lunden et al., 2002; Orsi et al., 2011). Based upon an anticipated requirement for L. monocytogenes to be able to balance survival under nutrient poor conditions in the outside environment with life within the infected host, we assessed the bacterium for its ability to adapt to periods of long-term stationary phase growth through the development of GASP. Our results indicate that L. monocytogenes is capable of stably adapting itself for long-term survival without compromising its ability to cause disease.