Microbial degradation of 2,5-diketopiperazines

Enrichment culture of soil samples with cyclo(Gly-Gly) and cyclo(Gly-l-Tyr) as a carbon and/or a nitrogen source resulted in the isolation of Arthrobacter sp. 1-3-1 and the coryneform rod bacterium, strain T-1-3-Y, as the bacteria which most highly assimilated cyclo(Gly-Gly) and cyclo(Gly-l-Tyr), respectively. Both bacteria had the enzyme activity hydrolyzing DKPs intracellularly in contrast to the extracellular cyclo(Gly-Gly) hydrolase reported previously. The cells of Arthrobacter sp. 1-3-1 degraded all diketopiperazines tested, including cyclo(Gly-Gly), cyclo(Gly-l-Ala), cyclo(Gly-l-Val), cyclo(Gly-l-Leu), cyclo(Gly-l-Ile), cyclo(Gly-l-Met), cyclo(Gly-l-Phe), cyclo(Gly-l-Tyr), cyclo(l-Ala-l-Tyr), cyclo(l-Val-l-Tyr), cyclo(l-Leu-l-Tyr), cyclo(l-Tyr-l-Tyr), cyclo(l-Phe-l-Leu), cyclo(Gly-d-Ala), and cyclo(Gly-d-Leu). On the other hand, the degradation of d-amino acid-containing DKPs or cyclo(Gly-Gly) by the cells of the strain T-1-3-Y were detected hardly or not at all, respectively. From the result that DKP hydrolase in the strain T-1-3-Y had a higher stereospecificity than that in Arthrobacter sp. 1-3-1, the diversity of DKP hydrolases were found to be in nature.