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United States Department of Agriculture

Agricultural Research Service

Research Project: FARMING PRACTICES FOR THE NORTHERN CORN BELT TO PROTECT SOIL RESOURCES, SUPPORT BIOFUEL PRODUCTION AND REDUCE GLOBAL WARMING POTENTIAL

Location: Soil and Water Management Research

Title: Rapid and Complete Degradation of the Herbicide Picloram by Lipomyces kononenkoaee

Authors
item Sadowsky, Michael -
item Koskinen, William
item Bischoff, Marianne -
item Barber, Brian -
item Becker, Joanna -
item Turco, Ronald -

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 13, 2009
Publication Date: April 24, 2009
Repository URL: http://hdl.handle.net/10113/32842
Citation: Sadowsky, M.J., Koskinen, W.C., Bischoff, M., Barber, B.L., Becker, J.M., Turco, R.F. 2009. Rapid and Complete Degradation of the Herbicide Picloram by Lipomyces kononenkoaee. Journal of Agricultural and Food Chemistry. 57(11):4878-4882.

Interpretive Summary: An enrichment culture approach was used to isolate a pure culture of the yeast Lipomyces kononenkoae, which had the ability to grow on the herbicide picloram. The yeast rapidly and completely degraded 50 µg/mL picloram by 48 hr of growth. While L. kononenkoae was found to use both N atoms of picloram as a sole nitrogen source for growth, it failed to mineralize the herbicide or use it as a sole C source. Product analysis done using liquid chromatrograpy-mass spectrometry indicated that biodegradation of picloram by L. kononenkoae proceeds via a didechlorinated, dihydroxylated pyridinecarboxylic acid breakdown product. Our results are consistent with the hypothesis that the majority of picloram degradation in the soil is likely due to microbial catabolic processes. Since degradation of picloram by Lipomyces kononenkoae was very rapid, it was not possible to detect the initial degradation products, even with the short incubation times used in our studies. However, scientist have the important first information needed to develop a complete understanding of the complete picloram biodegradation pathway in L. kononenkoae, which will require further isotopic, mutational, gene cloning, and biochemical analyses.

Technical Abstract: An enrichment culture approach was used to isolate a pure culture of the yeast Lipomyces kononenkoae, which had the ability to grow on the herbicide picloram. The yeast rapidly and completely degraded 50 µg/mL picloram by 48 hr of growth. While L. kononenkoae was found to use both N atoms of picloram as a sole nitrogen source for growth, it failed to mineralize the herbicide or use it as a sole C source. Product analysis done using LC-ESI-MS indicated that biodegradation of picloram by L. kononenkoae proceeds via a didechlorinated, dihydroxylated pyridinecarboxylic acid derivative. Our results are consistent with the hypothesis that the majority of picloram degradation in the soil is likely due to microbial catabolic processes.

Last Modified: 4/16/2014