Biodegradation and growth characteristics of a toluene-degrading strain

Abstract

A toluene-degrading strain was isolated from active sludge in this study. Both growth characteristic and the performance to degrade toluene by the strain in batch culture mode were evaluated. Results showed that the isolated strain presented a good ability to remove toluene with the maximum removal efficiency of 93.8%. Growth and toluene degradation occurred at 20 to 50°C but the optimum was found to be 30°C for both. The optimal pH for growth and toluene degradation was 6.5. Lower toluene concentrations (1.19 to 2.45 mg/l) promoted faster growth rates than higher concentrations (3.28 to 6.17 mg/l) during the first 20 h; this could be probably due to the substrate inhibition effects. The removal efficiencies of toluene (90 to 95%) were almost the same within the concentrations ranges (1.19 to 6.17 mg/l). Kinetic analysis results indicated that the biodegradation of toluene followed first-order kinetics, and the removal rate constant (k) was 0.0385. Finally, the isolated strain was identified as Pseudomonas sp. using 16S rDNA sequencing.

Keywords: Biodegradation, growth characteristic, toluene, Pseudomonas.