Recent advances in understanding resin acid biodegradation: microbial diversity and metabolism |
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Authors: | Vincent J J Martin Zhongtang Yu W W Mohn |
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Institution: | (1) Department of Microbiology and Immunology and Pulp and Paper Centre, University of British Columbia, 300-6174 University Boulevard, Vancouver, British Columbia V6T 1Z3, Canada e-mail: wmohn@interchange.ubc.ca Tel.: +1-604-8224285, Fax: +1-604-8226041, CA |
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Abstract: | Resin acids are tricyclic diterpenoids that are found in the oleoresin of coniferous trees. Resin-acid-degrading microorganisms
are ubiquitous in the environment. The bacterial isolates that grow on resin acids as sole organic substrates are physiologically
and phylogenetically diverse, and include psychrotolerant, mesophilic, and thermophilic bacteria. Recent studies of the biodegradation
of resin acids by these organisms have demonstrated that in gram-negative bacteria, distinct biochemical pathways exist for
the degradation of abietane- and pimerane-type resin acids. One of these organisms, Pseudomonas abietaniphila BKME-9, harbors a convergent pathway that channels the nonaromatic abietanes and dehydroabietic acid into 7-oxodehydroabietic
acid. This dioxygenolytic pathway is encoded by the recently cloned and sequenced dit gene cluster. The dit cluster encodes the ferredoxin and the α- and β-subunits of a new class of ring-hydroxylating dioxygenases as well as an
extradiol ring-cleavage dioxygenase. Although it was previously thought that resin acids are very recalcitrant under anoxic
conditions, recent investigations have demonstrated that they are partially metabolized under anoxic conditions by undefined
microorganisms. The anaerobic degradation of resin acids principally generates aromatized and decarboxylated products (such
as retene) that are thought to persist in the environment.
Received: 9 April 1999 / Accepted: 1 July 1999 |
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Keywords: | Resin acid Abietane Pimerane Diversity Biodegradation Dioxygenase Diterpene |
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