Biomedical Engineering Reference
In-Depth Information
Table 1.3. Methods to Monitor Inoculum Survival and Pollutant Degradation
Target
Method Type
Name
Description
Quantitative?
Plating
Growth of the inoculum
on plates demonstrates
presence of the organism
Yes
MPN
Dilution of the inoculated
site medium to verify
inoculum presence
Yes
Microbiology
Microscopy
Hybridization of site media
with a fluorescent probe
specific for the inoculum
Semi
Inoculum
Bioluminescent
strains
Genetically-modified strains
that carry a bioluminescent
gene
Semi
PCR, RT-PCR
of 16 S rRNA
Detection of the 16 S rRNA
of the inoculated strains
Semi
qPCR, RT-qPCR Detection of the genes and
transcripts of interest
Yes
Molecular biology
Microarray
DNA probes on a chip are
used to detect multiple
genes simultaneously
Semi
Metabolic
biomarkers
Detecting biologically-
specific pollutant
degradation intermediates
No
Microbiology
Push-pull test
Isotope-tagged pollutants
are injected into the site
and retrieved to evaluate
degradation
No
Microelectrodes Use of electrodes to detect
the presence of target
pollutants
Yes
Pollutant
Compound specific
isotope analysis
(CSIA)
Examination of pollutant
isotope ratios to detect
isotope fractionation
No
Physicochemistry
Analytical
chromatography
Extraction of the pollutant
from the medium and direct
detection based on chemical
characteristics
Yes
The pollutant concentration itself can be monitored in a number of ways. Compounds that
result from the biodegradation of certain pollutants can be used as markers, or more specifi-
cally metabolic biomarkers (Smets and Pritchard, 2003 ). Each metabolic biomarker should be an
intermediate specific to the degradation of the pollutant of interest and be degraded easily to
indicate ongoing degradation. In a push-pull test, isotope-tagged pollutants are injected into
aquifers, briefly exposed to the bacteria, then quickly retrieved and analyzed for degradation
(Scow and Hicks, 2005 ; Lee et al., 2010 ). Compound-specific isotope analysis (CSIA) exploits
the preference of biological systems for certain stable isotopes, resulting in isotopic fraction-
ation. CSIA is a powerful and sensitive technique that can be used to determine conclusively
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