Development of Bioaugmentation Technologies for Cleaning Up
Soil and Groundwater Contaminated with Trichloroethylene
Kazuhiro IWASAKI*, Osami YAGI** and Futoshi KURISU*** National Institute for Environmental Studies and** Research Center for Water Environment Technology, The University of Tokyo

lab scale experiments
CA

Development of monitring
system for TCE-degrading
bacterium

B

pMMO gene cluster
X

YB

Z

Soil column
3 cm x 40 cm)

CsMMO gene cluster

pilot scale experiments
TCE

Methylocystis sp. M

NADHO2
H 2O

NAD+TCEoxidePSoluble methane monooxygenase (sMMO)

P50 cmsoil150cm

Analysis of the regulatory
mechanism of MMO gene
expression

200 cmSandy soil lysimeter

The contamination of groundwater and soil with volatile

Methanotrophic bacteria are able to oxidize methane tochlorinated aliphatic compounds, such as trichloroethylene (TCE),

methanol by the catalytic function of methane monooxygenases

has become a serious environmental problem. While TCE has a(MMOs). Two different types of MMO are known: a membrane-large number of industrial applications as a solvent and degreaser,

bound particulate enzyme (pMMO), which is found in all

inadequate disposal techniques or accidental spillage havemethanotrophs, and a soluble cytoplasmic enzyme (sMMO), which

threatened drinking water supplies because of its toxicity andhas been found in several strains. The substrate specificity ofcarcinogenicity.

clean-up

pMMO is narrow. In contrast, sMMO has broad substratetechnologies are now being developed. Physical and chemical

specificity and can oxidize a wide range of alkanes, alkenes andmethods such as soil incineration, vapor-extraction and pumping-aromatic compounds, including TCE.

Varioussoiland

groundwater

up and treatment are very common approaches. Bioremediation isWe have isolated a methanotroph, Methylocystis sp. M, which

one of the most promising new technologies for cleaning up soil

has high TCE-degradation activity, and studied on its TCE

and groundwater contamination, because of its low cost anddegradation characteristics in lab scale experiments. For effective

complete destruction of pollutants. However, we have not muchapplication of Methylocystis sp. M to bioaugmentation, we haveexperience on bioremediation in Japan.

focused on following 3 subjects.

Several studies of microbial aerobic degradation of TCE have

1. Developmentofmonitoring

systemforTCE-degrading

shown that TCE can be degraded by toluene-oxidizing bacteria,bacterium, Methylocystis sp. M, and Construction of simulation

phenol-oxidizing bacteria and methanotrophic bacteria. Thesemodel of fate of Methylocystis sp. M in groundwater

TCE-degrading bacteria require some organic substrates, such as

2. Analysis of the regulatory mechanism of MMO gene expression,

toluene, phenol and methane, to induce their TCE-degradation

and Decision of optimum condition for expression of TCE-activity. Methane is less toxic to humans than aromatic compounds.

degrading activity

Therefore, methanotrophs have been receiving attention for their

3. Development of efficacy measurement technologies andpossible application to the bioaugmentation of polluted soil andeffective application methods of Methylocystis sp. M in pilot

groundwater.

scale experiments (using sandy soil lysimeter)