Kinetics of High Concentrated Phenol Biodegradation by Acinetobacter Baumannii

摘要

Acinetobacter baumannii was isolated and tested for phenol degradation. This bacterium has high phenol degradation activity and high tolerance to phenol. The biodegradation assays were performed in liquid medium with the phenol as single substrate. Different concentrations of phenol samples ranging from 125 mg/lit to 1000 mg/lit were taken for observations. The bioremediation potential of an indigenous Acinetobacter baumanniiwas studied in batch culture using synthetic phenol in water in the concentration range of (125 -1000) mg/L as a limiting substrate. The effect of initial phenol concentration on the degradation process was investigated.Phenol was completely degraded at different cultivation times with different initial phenol concentrations. Increasing the initial phenol concentration from 125 mg/L to 1000 mg/L increased the lag phase from 0 to 48 h and correspondingly prolonged the degradation process from 84 h to 354 h. There was decrease in biodegradation rate as initial phenol concentration increased. Fitting data into Monod kinetic model showed the inhibition effect of phenoL The kinetic parameters have been estirnated.The rsmax decreased and Ks increased with higher concentration of phenoL The rsmax has been foundto be a strong function of initial phenol concentratioa The culture followed substrate inhibition kinetics and the specific phenol consumption rates were fitted to Haldane, Yano and Koga, Aiba et aL, Teissier and Webb models. Between the five inhibitionmodels, the Monod model was found to give the best fit. Therefore, the biokinetic constants estimated using these models showed good potential of the Acinetobacter baumannii and the possibility of using it in bioremediation of phenol waste effluents. The results indicated that in 48 hrs of incubation the bacterium was able to reduce the phenol concentrations to below detection limits. Outcomes of this study offer a useful guideline in evaluating potential phenol degraders from the environment.