Suicide through stress: A bacterial response to sub-lethal injury in the food environment

Resistance and survival strategies of Salmonella enterica to environmental stresses

“…As a result of their life cycle, salmonellae often suffer periods of nutrient starvation as they voyage through different natural, commercial, and host microenvironments they encounter (Abshire & Neidhardt, 1993;Dodd et al, 2007;Fang et al, 1992;Grant et al, 2009;Humphreys, Stevenson, Bacon, Weinhardt, & Roberts, 1999;Koch, 1971;Roszak et al, 1984;Rychlik & Barrow, 2005;Spector, 1998;Testerman et al, 2002;Turpin et al, 1993;Winfield & Groisman, 2003). Unlike endosporeforming bacteria, Salmonella and other enterobacteria depend upon different types of "programmed" physiologic responses for survival during periods of nutrient starvation, that are functionally analogous to sporulation but do not technically result in a structurally distinct "differentiated" cell form (i.e., an endospore).…”

“…This is particularly vital for foodborne microbial pathogens that can encounter potentially life-threatening conditions in virtually every environment they may find themselves including: natural (e.g., soil, water systems), commercial (e.g., slaughter houses, food processing plants) and host (e.g., animals, humans) settings (Winfield & Groisman, 2003). Responses to these conditions not only impact growth and survival but can also influence virulence and resistance to multiple antimicrobics (Altier, 2005;Clements, Ericksson, Tezcan-Merdol, Hinton, & Rhen, 2001;Dodd, Richards, & Aldsworth, 2007;Grant et al, 2009;Kenyon & Spector, 2011;McMahon, Xu, Moore, Blair, & McDowell, 2007;McMeechan et al, 2007;Rowley, Spector, Kormanec, & Roberts, 2006). Few microorganisms are as capable of coping with the range of stresses present in natural, commercial and host microenvironments as Salmonella enterica serovars (Cabello, Hormaeche, Mastroeni, & Bonina, 1993;D' Aoust, Maurer, & Bailey, 2001;Kenyon & Spector, 2011;Rychlik & Barrow, 2005;Stocker & Makela, 1986).…”

Impact of Nutritional Factors on the Proteome of Intestinal Escherichia coli: Induction of OxyR-Dependent Proteins AhpF and Dps by a Lactose-Rich Diet

“…The "suicide through stress" theory proposes that bacteria produce a burst of intracellular free radicals such as H 2 O 2 and O 2 Ϫ under conditions of heat, osmotic, or ethanol stress, leading to cell injury or death. These free radicals have so far been identified only in aerobic organisms with respiratory metabolism (Salmonella enterica serovars, E. coli, Staphylococcus aureus, Mycobacterium smegmatis) but not in a strictly fermentative organism (Streptococcus mutans), leading to the assumption that the proposed suicide response is linked to aerobic metabolism (10). In our experiments, induction of OxyRdependent genes occurred under both aerobic and anaerobic conditions.…”

“…One scenario explaining how such DNA damage is caused might be the formation of free radicals in response to osmotic stress as proposed by Aldsworth et al (1,10). The "suicide through stress" theory proposes that bacteria produce a burst of intracellular free radicals such as H 2 O 2 and O 2 Ϫ under conditions of heat, osmotic, or ethanol stress, leading to cell injury or death.…”

“…Aldsworth and Dodd proposed that free radicals are formed in response to heat, osmotic stress, or ethanol stress (1,10). To elucidate the relation between free radical formation and the observed induction of OxyR-dependent genes, dihydrorhodamine 123-stained E. coli cells were exposed to H 2 O 2 , glucose, lactose, or sucrose (Fig.…”