Toluene biodegradation by Emphasis Type="Italic"

Authors: Luis Felipe Díaz Raúl Muñoz Sergio Bordel Santiago Villaverde

Publish Date: 2007/05/09

Volume: 19, Issue: 2, Pages: 197-208

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Abstract

The stability of Pseudomonas putida F1 a strain harbouring the genes responsible for toluene degradation in the chromosome was evaluated in a bioscrubber under high toluene loadings and nitrogen limiting conditions at two dilution rates 011 and 027 h−1 Each experiment was run for 30 days period long enough for microbial instability to occur considering previously reported studies carried out with bacterial strains encoding the catabolic genes in the TOL plasmid At all tested conditions P putida F1 exhibited stable performance as shown by the constant values of the specific toluene degradation yield CO2 produced versus toluene degraded yield and biomass concentration within each steady state Benzyl alcohol a curing agent causing TOL plasmid deletion in Pseudomonas strains was present in the cultivation medium as a result of the monooxygenation of toluene by the diooxygenase system of P putida F1 However no mutant population growing at the expense of the extracellular excreted carbon or lysis products was established in the chemostat as confirmed by the constant dissolved total organic carbon TOC concentration and fraction of toluene degrading cells approx 100 In addition batch experiments conducted with both lysis substrate and toluene simultaneously confirmed that P putida F1 preferentially consumed toluene rather than extracellular excreted carbon

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