Differential efficiency of induction of various lambdoid prophages responsible for production of Shiga toxins in response to different induction agents

Łoś, Jerzy; Łoś, Marcin; Węgrzyn, Grzegorz; Węgrzyn, Alicja

doi:10.1016/j.micpath.2009.09.006

Cited by 81 publications

(68 citation statements)

References 30 publications

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“…89 The antibiotic norflaxicin and H 2 O 2 were also both shown to induce stx-bearing prophages from STEC. 90 Los et al 91 have postulated that oxidative stress, which may occur during intestinal colonisation and neutrophil-produced H 2 O 2 , may increase production of Shiga toxin as a result of stx-converting prophages in STEC bacteria.…”

Section: Prophages Are the Major Drivers Of Microbial Evolution And Dmentioning

confidence: 99%

Movers and shakers

et al. 2013

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Section: Prophages Are the Major Drivers Of Microbial Evolution And Dmentioning

confidence: 99%

Movers and shakers

et al. 2013

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“…Second, natural environments are more variable than the assay conditions of this study. For example, it is known that lambdoid prophages vary both in their sensitivity toward an inducing signal and in their response towards different signals (Łoś et al, 2009;Refardt and Rainey 2010). Finally, it is also conceivable that competitive ability depends on the host genotype (de Roode et al, 2004).…”

Section: Patterns Of Competitive Interactions Among Lambdoid Phagesmentioning

confidence: 99%

Within-host competition determines reproductive success of temperate bacteriophages

Refardt

2011

The ISME Journal

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Within-host competition between parasites is frequently invoked as a major force for parasite evolution, yet quantitative studies on its extent in an organismal group are lacking. Temperate bacteriophages are diverse and abundant parasites of bacteria, distinguished by their ability to enter a facultative dormant state in their host. Bacteria can accumulate multiple phages that may eventually abandon dormancy in response to host stress. Host resources are then converted into phage particles, whose release requires cell death. To study within-host competition between phages, I used the bacterium Escherichia coli and 11 lambdoid phages to construct single and double lysogens. Lysogenic bacterial cultures were then induced and time to host cell lysis and productivity of phages was measured. In double lysogens, this revealed strong competitive interactions as in all cases productivity of at least one phage declined. The outcome of within-host competition was often asymmetrical, and phages were found to vary hierarchically in within-host competitive ability. In double infections, the phage with the shorter lysis time determined the timing of cell lysis, which was associated with a competitive advantage when time differences were large. The results emphasize that within-host competition greatly affects phage fitness and that multiple infections should be considered an integral part of bacteriophage ecology.

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“…Classical techniques for the evaluation prophage induction employ plaque assays (21,24), protein assays (6,10), and quantification of gene expression (25); however, these methods inform only on prophage induction at a population level. Using a fluorescent reporter gene to replace stx 2 was done in previous studies to investigate the induction of Stx2 prophages (6,26).…”

Section: Discussionmentioning

confidence: 99%

“…The peroxide-induced SOS response leading to cell filamentation (29), RecA-dependent gene regulation (29)(30)(31), and prophage induction (21,26) is well documented. The present study additionally documents RecA-independent induction of the Stx2-converting prophage.…”

Section: Discussionmentioning

confidence: 99%

“…The Stx-phage released in the intestine may transduce to commensal strains and thus amplify toxin production and exacerbate disease symptoms (10). Hydrostatic pressure, a physical method of food preservation, also induces Stx prophages (18,21). Prophage induction in any of the ecological niches populated by STEC drives horizontal gene transfer by release of infectious phage particles that allows transduction of Shiga toxin-negative phages and thus disseminates genes coding for the Shiga toxin in intestinal and food systems.…”

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Induction of Shiga Toxin-Encoding Prophage by Abiotic Environmental Stress in Food

Fang

Mercer

McMullen

et al. 2017

Appl Environ Microbiol

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The prophage-encoded Shiga toxin is a major virulence factor in Stxproducing Escherichia coli (STEC). Toxin production and phage production are linked and occur after induction of the RecA-dependent SOS response. However, foodrelated stress and Stx-prophage induction have not been studied at the single-cell level. This study investigated the effects of abiotic environmental stress on stx expression by single-cell quantification of gene expression in STEC O104:H4 Δstx2::gfp:: amp r . In addition, the effect of stress on production of phage particles was determined. The lethality of stressors, including heat, HCl, lactic acid, hydrogen peroxide, and high hydrostatic pressure, was selected to reduce cell counts by 1 to 2 log CFU/ml. The integrity of the bacterial membrane after exposure to stress was measured by propidium iodide (PI). The fluorescent signals of green fluorescent protein (GFP) and PI were quantified by flow cytometry. The mechanism of prophage induction by stress was evaluated by relative gene expression of recA and cell morphology. Acid (pH Ͻ 3.5) and H 2 O 2 (2.5 mM) induced the expression of stx 2 in about 18% and 3% of the population, respectively. The mechanism of prophage induction by acid differs from that of induction by H 2 O 2 . H 2 O 2 induction but not acid induction corresponded to production of infectious phage particles, upregulation of recA, and cell filamentation. Pressure (200 MPa) or heat did not induce the Stx2-encoding prophage (Stx2-prophage). Overall, the quantification method developed in this study allowed investigation of prophage induction and physiological properties at the single-cell level. H 2 O 2 and acids mediate different pathways to induce Stx2-prophage.IMPORTANCE Induction of the Stx-prophage in STEC results in production of phage particles and Stx and thus relates to virulence as well as the transduction of virulence genes. This study developed a method for a detection of the induction of Stxprophages at the single-cell level; membrane permeability and an indication of SOS response to environmental stress were additionally assessed. H 2 O 2 and mitomycin C induced expression of the prophage and activated a SOS response. In contrast, HCl and lactic acid induced the Stx-prophage but not the SOS response. The lifestyle of STEC exposes the organism to intestinal and extraintestinal environments that impose oxidative and acid stress. A more thorough understanding of the influence of food processing-related stressors on Stx-prophage expression thus facilitates control of STEC in food systems by minimizing prophage induction during food production and storage.KEYWORDS single-cell detection, E. coli O104:H4, prophage induction, environmental stress, RecA-independent SOS response, membrane permeability, STEC, Shiga toxin, Shiga toxin-producing E. coli S higa toxin-producing Escherichia coli (STEC) causes the life-threatening hemolyticuremic syndrome (HUS), which is associated with acute renal failure and significant mortality (1, 2). Shiga toxins (Stx) include St...

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Differential efficiency of induction of various lambdoid prophages responsible for production of Shiga toxins in response to different induction agents

Cited by 81 publications

References 30 publications

Movers and shakers

Movers and shakers

Within-host competition determines reproductive success of temperate bacteriophages

Induction of Shiga Toxin-Encoding Prophage by Abiotic Environmental Stress in Food

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