The trans-Anethole Degradation Pathway in an
Arthrobacter sp.*
Eyal
Shimoni
,
Timor
Baasov§¶,
Uzi
Ravid
, and
Yuval
Shoham
¶**
From the
Department of Food Engineering and
Biotechnology, § Department of Chemistry, and
¶ Institute of Catalysis Science and Technology, Technion-Israel
Institute of Technology, Haifa 32000, and Agricultural Research
Organization,
Newe Ya'ar Research Center, P. O. Box
1021, Ramat Yishai 30095, Israel
A bacterial strain (TA13) capable of
utilizing t-anethole as the sole carbon source was isolated
from soil. The strain was identified as Arthrobacter
aurescens based on its 16 S rRNA gene sequence. Key steps of the
degradation pathway of t-anethole were identified by the
use of t-anethole-blocked mutants and specific inducible enzymatic activities. In addition to t-anethole,
strain TA13 is capable of utilizing anisic acid, anisaldehyde, and
anisic alcohol as the sole carbon source.
t-Anethole-blocked mutants were obtained following
mutagenesis and penicillin enrichment. Some of these blocked mutants,
accumulated in the presence of t-anethole quantitative
amounts of t-anethole-diol, anisic acid, and
4,6-dicarboxy-2-pyrone and traces of anisic alcohol and anisaldehyde. Enzymatic activities induced by t-anethole included:
4-methoxybenzoate O-demethylase,
p-hydroxybenzoate 3-hydroxylase, and
protocatechuate-4,5-dioxygenase. These findings indicate that
t-anethole is metabolized to protocatechuic acid through
t-anethole-diol, anisaldehyde, anisic acid, and
p-hydroxybenzoic acid. The protocatechuic acid is then
cleaved by protocatechuate-4,5-dioxygenase to yield 2-hydroxy-4-carboxy
muconate-semialdehyde. Results from inducible uptake ability and
enzymatic assays indicate that at least three regulatory units are
involved in the t-anethole degradation pathway. These
findings provide new routes for environmental friendly production
processes of valuable aromatic chemicals via bioconversion of phenylpropenoids.
*
This work was supported by the Fund for the Promotion of
Research at the Technion and grants from the Israeli Ministry of Agriculture.The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in
accordance with 18 U.S.C. Section
1734 solely to indicate this fact.