Biosensing 2,4-Dichlorophenol Toxicity during Biodegradation by Burkholderia sp. RASC c2 in Soil

Abstract

Biodegradation of the model pollutant, 2,4-dichlorophenol (2,4-DCP) by Burkholderia sp. RASC c2, in contaminated soil was assessed by combining chemical analysis with a toxicity test using Escherichia coli HB101 pUCD607. E. coli HB101 pUCD607 was previously marked with luxCDABE genes, encoding bacterial bioluminescence and was used as an alternative to Microtox. Mineralization of 14C-2,4-DCP (196.2 μg g-1 dry wt) in soil occurred rapidly after a 24 h lag. Correspondingly, 2,4-DCP concentrations in soil and soil water extracts decreased with time and concentrations in the latter were at background levels (<0.12 μg mL-1) after day 2. Toxicity of soil water extracts to the lux-based biosensor also decreased with time. Mean light output of E. coli was stimulated by ∼1.5 X control values in soil water extracts when concentrations of 2,4-DCP were approaching the limit of detection by HPLC but returned to values equivalent to those of controls when soil water 2,4-DCP concentrations were below the detection limit...