Shigatoxin encoding Bacteriophage ϕ24B modulates bacterial metabolism to raise antimicrobial tolerance

Abstract

How temperate bacteriophages play a role in microbial infection and disease progression is not fully understood. They do this in part by carrying genes that promote positive evolutionary selection for the lysogen. Using Biolog phenotype microarrays and comparative metabolite profiling we demonstrate the impact of the well-characterised Shiga toxin-prophage φ24 B on its Escherichia coli host MC1061. As a lysogen, the prophage alters the bacterial physiology by increasing the rates of respiration and cell proliferation. This is the first reported study detailing phage-mediated control of the E. coli biotin and fatty acid synthesis that is rate limiting to cell growth. Through φ24 B conversion the lysogen also gains increased antimicrobial tolerance to chloroxylenol and 8-hydroxyquinoline. Distinct metabolite profiles discriminate between MC1061 and the φ24 B lysogen in standard culture, and when treated with 2 antimicrobials. This is also the first reported use of metabolite profiling to characterise the physiological impact of lysogeny under antimicrobial pressure. We propose that temperate phages do not need to carry antimicrobial resistance genes to play a significant role in tolerance to antimicrobials.Colonisation by Shiga toxin-encoding Escherichia coli (STEC) causes a potentially fatal gastrointestinal infection in humans. There are currently > 500 different characterised STEC serogroups that cause disease including O157:H7 and more recently O104:H4 1,2 . Symptoms of STEC infection can vary from bloody diarrhoea through to haemorrhagic colitis, thrombotic thrombocytopaenic purpura (TTP) and haemolytic-uraemic syndrome (HUS), the latter can be fatal 3,4 . STEC is a zoonotic infection transmitted from an animal reservoir via contaminated food or water 5 . Shiga toxins are responsible for the severe downstream sequelae due to high cytotoxicity to human renal microvascular endothelial cells 4,6 . Importantly, the genes encoding Shiga toxin (Stx) are disseminated by temperate bacteriophages.Stx-phages enter one of two replication pathways: a productive lytic life cycle or a more passive lysogenic cycle where the prophage is replicated by the bacterium as any other genetic loci. The lytic-lysogen decision of lambdoid-like bacteriophages is regulated by early gene expression and sequential binding of proteins to a well characterised genetic switch 7-9 .The co-evolutionary interaction between a phage and its bacterial host is dynamic, with interplay linked to rounds of inhibition, selection and evolution, often referred to as an 'arms race' 10 . Smith et al. 11 used a multi-loci PCR typing approach to demonstrate that no two Stx phage isolates had the same genotype 11 . This heterogeneity is further supported by Bonanno et al. 12 who identified multiple Stx-phage morphologies not previously reported 12 . Stx-phages are closely related to bacteriophage lambda, with a comparable genome organisation. In comparison to lambda, Stx-phages carry significantly larger amounts of DNA (~20-25 Kbp), with up to 73% of the geno...

Temperate Bacteriophages from Chronic Pseudomonas aeruginosa Lung Infections Show Disease-Specific Changes in Host Range and Modulate Antimicrobial Susceptibility

“…aeruginosa. This was previously described for phages transferring genes horizontally in Escherichia coli (40). Here, we showed that phages 24 (CF) and 200 (BR) when integrated into PAO1 as lysogens have the greatest impact reducing the susceptibility to the antibiotics tested.…”

Subtypes of NanS-p Sialate O-Acetylesterase Encoded by Stx2a Bacteriophages

“…Stx phages play key roles in STEC virulence because they not only carry Shiga toxin-encoding genes but also control their expression. However, little is known about the function of other phage-encoded proteins and how they impact on the host [12,20].…”

Lysogenisation of Shiga toxin-encoding bacteriophage represses cell motility

“…E. coli lacking cryptic prophages display decreased resistance to environmental stresses such as osmotic, oxidative, and acid stress, as well as antimicrobial agents (Wang et al, 2010). Lysogenisation of E. coli K-12 by F24 B , one of the Stx2 phages, modulates bacterial metabolism and raises antimicrobial tolerance (Holt et al, 2017). Therefore, phage lysogenisation enhances the survival of the host bacterium in adverse environmental conditions.…”

“…The number of phage particles in environmental samples is estimated to be 10-fold higher than results suggest that prophages alter the gene expression pattern of the host. The impact of Stx2 phage integration on gene expression in E. coli K-12 has been investigated (Holt et al, 2017;Su et al, 2010;Xu et al, 2012). However, the influence of environmental factors on Stx2 phagedriven changes in E. coli has not been clarified.…”