[Characteristics of 4-chlorophenol degradation by a soil bacterium Acinetobacter sp]

The bacterium capable of degrading 4-chlorophenol (4-CP) was enriched and isolated from agricultural soil. It was gram-negative, rod-shaped bacterium, and identified as Acinetobacter sp. based on the analysis of the 16S rRNA gene fragment. It was able to utilize 4-CP as a sole carbon source. The degradation mechanism of 4-CP by this isolate was proposed as a modified ortho-cleavage pathway, the activity of chlorocatechol 1,2-dioxygenase was markedly induced. The bacterial isolate grew well and exhibited a high degradation efficiency when the initial concentration of 4-CP was between 2-8 mmol/L. It was able to survive in the presence of 4-CP at higher concentrations (up to 8 mmol/L). Not only 4-CP, but also 2-chlorophenol, 3-chlorophenol, phenol, and 2,4-dichlorophenol, were also growth substrates for the isolate. The results of co-substrate supplementation illustrated the suitable conditions of the isolate to improve growth rate and 4-chlorophenol biodegradation efficiency. The results suggested that the isolate had a potential use for bioremediation of the site contaminated with 4-chlorophenol.