BIOAUGMENTATION FOR MTBE REMEDIATION - Bioaugmentation for Groundwater Remediation - page 288

Table 10.1. Functional and Molecular Techniques to Evaluate Bacterial Bioaugmentation for
MTBE Remediation in Aquifer Samples (Aquifer Sediment and Groundwater)
Method Feature Advantages Disadvantages

a See footnote

1. Biodegradation potential
assay

Lab microcosm
Aerobic/anaerobic
Test period (days,
weeks or months)

Estimate decay
coefficients (k 1 ,
K s ,S min )
Assess aerobic/
anaerobic
metabolism

2. Oligonucleotide probes
and polymerase chain
reaction (PCR)
for specific
MTBE-degraders:
Methylibrium
petroleiphilum (PM1)
L108
Mycobacterium
austroafrican
(IFP2012)
Hydrogenophaga flava
(ENV735)
Rhodococcus
aetherivorans
(SC-100)

DNA extraction,
amplification
and matching
to database
of type species
Genus and species
specific

Sequences of known
MTBE degraders
available
Enumerate
degraders
Number
of degraders may
correlate with
decay rates in situ

Presence of other unknown
MTBE-degraders in a
sample are not detected
Low levels of degraders may
not be detectable
(e.g., 10-100's per g soil)
Presence of a specific
MTBE- degrader may not
correlate with metabolic
activity in situ

3. Oligonucleotide probes
and PCR for MTBE
degrading enzymes

Amplification of DNA
coded enzyme
sequences
Available sequences
for: MTBE
monooxygenase,
isobutyl CoA b
mutase, tert-butyl
alcohol
dioxygenase)

Estimate level
of specific
metabolic genes
Copy numbers may
correlate
to MTBE decay
rate in situ

Specific enzyme sequence
may not be present in
sample and in all
environments
Enzyme levels in soil may not
correlate with degradative
activity

4. Compound specific stable
isotope analysis d

MTBE degradation
observed by
enrichment of
heavier isotopes
Compare source
with downgradient
plume for isotope
signatures

3-dimensional (3-D)
mass balance of
aquifer levels
of ether not
required
Aerobic
and anaerobic
metabolism
determined
Estimate fractional
amount of ether
present in an
aquifer

Aerobic degradation shows
little isotope enrichment
Isotope enrichment
in anaerobic conditions
shows metabolism only
to TBA
Expensive gas
chromatography (GC)/
mass spectrometer (MS)
and isotope ratio
spectrometer required
Confounding mixed
fractionation may occur in
aerobic/anaerobic zones
(continued)

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C-MTBE
d

2/1 H-MTBE