Thein vitroandin vivoeffects of constitutive light expression on a bioluminescent strain of the mouse enteropathogenCitrobacter rodentium

Abstract

Bioluminescent reporter genes, such as those from fireflies and bacteria, let researchers use light production as a non-invasive and non-destructive surrogate measure of microbial numbers in a wide variety of environments. As bioluminescence needs microbial metabolites, tagging microorganisms with luciferases means only live metabolically active cells are detected. Despite the wide use of bioluminescent reporter genes, very little is known about the impact of continuous (also called constitutive) light expression on tagged bacteria. We have previously made a bioluminescent strain of Citrobacter rodentium, a bacterium which infects laboratory mice in a similar way to how enteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC) infect humans. In this study, we compared the growth of the bioluminescent C. rodentium strain ICC180 with its non-bioluminescent parent (strain ICC169) in a wide variety of environments. To understand more about the metabolic burden of expressing light, we also compared the growth profiles of the two strains under approximately 2,000 different conditions. We found that constitutive light expression in ICC180 was near-neutral in almost every non-toxic environment tested. However, we also found that the non-bioluminescent parent strain has a competitive advantage over ICC180 during infection of adult mice, although this was not enough for ICC180 to be completely outcompeted. In conclusion, our data suggest that constitutive light expression is not metabolically costly to C. rodentium and supports the view that bioluminescent versions of microbes can be used as a substitute for their non-bioluminescent parents to study bacterial behaviour in a wide variety of environments.

Antibody Fc-receptor FcεR1γ stabilizes cell surface receptors in group 3 innate lymphoid cells and promotes anti-infection immunity

“…ILC3s have been reported to contribute to host defense against pathogens, such as intestinal C. rodentium , mainly through the production of IL-22 12 . To determine whether FcεR1γ was involved in the ILC3-mediated anti-infection immunity, we used a bioluminescent strain (ICC180) of C. rodentium 25 to trigger an immune response in the intestine (Fig. 3A ).…”

Expression of the lux genes in Streptococcus pneumoniae modulates pilus expression and virulence

“…This has been shown before in the gram- negative pathogen C . rodentium , where expression of the lux genes resulted in reduced virulence in a mouse model of infection [ 15 ]. Potential causes of this may be altered redox balance within the cell as the chemistry of light production requires large amounts of reducing power for the recycling of FMN to FMNH 2 ( Fig 9A ) [ 38 , 39 ].…”

“…A recent study showed that a constitutive expression of the genes required for bioluminescence in Citrobacter rodentium resulted in a competitive disadvantage in a mouse model of infection and impaired growth in minimal media [ 15 ]. We evaluated the phenotypic characteristics of Xen35 in a mouse model of infection and found that Xen35 was less virulent compared to the parent TIGR4.…”

A Bioluminescent Francisella tularensis SCHU S4 Strain Enables Noninvasive Tracking of Bacterial Dissemination and the Evaluation of Antibiotics in an Inhalational Mouse Model of Tularemia

“…Impaired growth in vitro as a function of light intensity has been reported for some bioluminescent Vibrio species (36) and for Streptococcus pyogenes (29). In addition, a competitive disadvantage at the site of infection in vivo has been reported for S. pyogenes (29) and Citrobacter rodentium (37).…”