The influence of green fluorescent protein incorporation on bacterial physiology: a note of caution.

AIMS

To investigate the effect of green flourescent protein (GFP) incorporation on bacterial physiology.

METHODS AND RESULTS

Comparisons were made between four different isogenic pairings of non-GFP-containing parents and their GFP-containing transformants with respect to growth rate and antimicrobial susceptibility. For the latter, sensitivities to 12 different antibiotics were measured initially by disc-diffusion assay, and then subsequently by generation of dose-dependent survival curves for 1 h exposure to different concentrations of tetracycline, ciprofloxacin and cetrimide USP. Whilst no significant difference in growth rate was observed, GFP-containing strains were uniformly and significantly more sensitive to all antimicrobial agents tested, excluding the beta-lactams, than their respective non-GFP-containing counterparts.

CONCLUSIONS

GFP incorporation has a significant effect on bacterial physiology and can modulate antimicrobial susceptibility.

SIGNIFICANCE AND IMPACT OF THE STUDY

Transformation with GFP can affect the physiology of bacterial cells. This may therefore affect the quality and accuracy of data generated depending on the application for which GFP is used.