Propachlor removal by Pseudomonas strain GCH1 in an immobilized-cell system

A bacterial strain capable of growing on propachlor (2-chloro-N-isopropylac etanilide) was isolated from soil by using enrichment and isolation techniq ues. The strain isolated, designated GCH1, was classified as a member of th e genus Pseudomonas. Washed-cell suspensions of strain GCH1 accumulated N-i sopropylacetanilide, acetanilide, acetamide, and catechol, Pseudomonas stra in GCH1 grew on propachlor with a generation time of 4.2 h and a rate of su bstrate utilization of 1.75 +/- 0.15 mu mol h(-1). Gene expression did not require induction but was subject to catabolite expression. Acetanilide was a growth substrate with a yield of 0.56 +/- 0.02 mg of protein mu mol(-1): GCH1 strain cells were immobilized by adsorption onto a ceramic support an d were used as biocatalysts in an Immobilized cell system, Propachlor elimi nation reached 98%, with a retention time of 3 h and an initial organic loa d of 0.5 mM propachlor. The viability of immobilized cells increased 34-fol d after 120 days of bioreactor operation.