Genetically engineered
Pseudomonas putida
reporters (BMB-PL and BMB-ME), which, respectively,
carried
phnS-luxCDABE and
merR-egfp cassette,were used to
determine bioavailable phenanthrene and mercury. Over a
spiked range of concentrations and aged for 6 days in red
soil samples, the reporters were tested to determine the optimal
assay conditions and the bioavailable phenanthrene
(0–60 mg kg
-1) and Hg
2+ (0–240 μg kg
-1) were evaluated
by the signal of the relative fluorescent units and relative
luminescence units. Single contaminationwas carried out and
good correlations were obtained between signal strength and
pollutant concentrations, whereas interference and bioavailability
repression were observed in dual-contamination
experiments. Other heavy metal ions at nanomolar level did
not interfere with BMB-ME measurement while BMB-PL
showed some response to other polycyclic aromatic hydrocarbons
or their intermediate products during degradation.
Comparing high-performance liquid chromatography methods
with the bacterial reporters, both BMB-MEand BMB-PL
appeared to have a detection limit (mercury <40 μg kg
-1;
phenanthrene <24 mg kg
-1) similar to the instrumental
analysis. Although physical parameters may affect the interaction
of pollutants with bioreporter cells, advantages include
the inherent biological relevance of the response, rapid
response time, and potential for field deployment. Our results
strongly suggest that theBMB-ME andBMB-PL bioreporters
constitute an adaptable system for easily detecting the bioavailability
of mercury and phenanthrene in the red soils.
