Isolation and characterization of a novel [epsilon]-caprolactam-degrading microbe, Acinetobacter calcoaceticus, from industrial wastewater by chemostat-enrichment

For the isolation of a [straight epsilon]-caprolactam-degrading microbe from wastewaters of a factory producing caprolactam, we applied a chemostat-enrichment technique with a selective medium containing caprolactam as sole source of carbon and nitrogen. This allowed for the isolation of a novel caprolactam-degrading microbe, identified as Acinetobacter calcoaceticus. The strain had a critical tolerance of 19 g caprolactam l^sup -1^ in minimal medium, which is higher than any previously reported caprolactam-degrading microbe. A. calcoaceticus also decreased the caprolactam content in medium by 65 % within 72 h despite the high caprolactam content (10 g l^sup -1^). This study highlights the potential use of A. calcoaceticus strain for the bioremediation of recalcitrant synthetic polymers, such as caprolactam.[PUBLICATION ABSTRACT]