Abstract:
This study explored the construction of bioluminescent E. coli strains through the integration of a chromosomal vector containing lux genes or random insertion of lux genes into the bacterial genome. Parameters such as growth and sensitivity to antimicrobials were measured and compared between the wild-type parent and lux-tagged strains of bacteria. The optical density was monitored over 6.5 hours for wild-type and parent strains of bacteria to determine growth characteristics. For the wild-type and lux-tagged strains, the area under the curve (AUC) analysis determined there was no significance difference in growth. Light levels were also measured in addition for the lux-tagged bacterial strains and constitutive levels of light were produced by bacteria. In addition, antimicrobial sensitivity was measured for both the parent and the lux-tagged strains by using broth microdilution in 96-well microtitre plates. The classical method of minimum inhibitory concentration (MIC) determination of antimicrobials was employed for parent and lux-tagged strains. Also, the MIC for antimicrobials tested against lux-tagged strains’ were determined by the measurement of light levels produced by bacteria as living bacteria produce light and growth-inhibited bacteria do not. It was found parent and lux-tagged strains were both sensitive to antimicrobials though statistically significant differences were found for two strains of E. coli when both methods compared with each other. The use of lux-tagged bioluminescent bacteria could be applied to other situations apart from antimicrobial testing. This includes use in anti-fouling tests and the in vivo biofilm model.
