Rapid and Complete Degradation of the Herbicide Picloram by Lipomyces kononenkoae

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 mu g mL(-1) picloram by 48 h 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.