Studying the behavior of the light-off bioreporter DF4/PUTK2 as a light-on assay against lead

Abstract

Recombinant bioluminescent bacteria are frequently directed towards use as environmental biosensors because it has high sensitivity, selectivity, costless, easy to use and function as rapid measurement to detect heavy metals. The bioluminescence of DF4/PUTK2 assay is based on using the bio-reporter Acinetobacter DF4/PUTK2 carrying luciferase genes luxCDABE which emit light constitutively. This can be measured in time intervals by luminometer to determine the behavior of bio-reporter against lead. The light emitted in the lead treated samples was equal or increased than the control. Therefore, the bio-reporter DF4/PUTK2 was subjected to intensive studies to elucidate its behavior with lead and if it was possible to be employed as a lead light-on assay in water in reverse order. Time exposure (5 to 990 min), lead concentration (0 to 30000 ppm), and lead salts (acetate-chloride and nitrate) were included in this study. The bio-reporter DF4/PUTK2 was more sensitive to lead concentrations range (19.25 to 15000 ppm). However, at high concentrations of lead, the light was being decreased due to cell death and/or metabolic burden simultaneously. It was possible to detect the presence of lead in water samples through light-induction in specific concentrations which add another advantage to the bio-reporter DF4/PUTK2.