Isolation and characterization of 4-chloroaniline-degrading bacteria

Abstract

Chloroanilines have been widely used in several industries such as insecticides and herbicides etc. It is also accumulated in the environment owing to the microbial degradation of various types of chemical substances, namely, herbicides, phenyl urea, acylanilide, and phenylcarbamate. Three bacterial strains enabled to degrade 4CA were isolated from Thailand agricultural soil. they were identified based on the basis of morphology, biochemical characteristics and comparison of 16S rDNA sequence. These strains wer Acinetobacter baumannii, Pseudomonas putida, and Klebsiella pneumoniae. These bacteria showed the highest degradation rate and exhibited the percentage of 4-chloroaniline biodegradation were 61.00%±1.68, 59.82%±1.68, 59.82%±0.71, and 62.82%±3.87, respectively at 25 ppm (0.2 mM) of 4-chloroaniline which incubated for 12 days at 30℃. Furthermore, the dechlorination was monitored for the 4-chloroaniline degradation. Acinetobacter baumannii, Pseudomonas putida, and Klebsiella pneumoniae showed high chlorocatechol 1, 2 dioxygenase activity and fair activity of catechol 1,2 dioxegenase. Thesefore, the biodegradation of 4-chloroaniline by these three isolates was occured via the modified ortho-pathway. Moreover, the additional carbon or/and nitrogen source to enhance 4-chloroaniline degradation are, for Acinetobacter baumannii: 4mM citrate, 4mM NH₄Cl and 4mM citrate + 4mM NH₄Cl; for Pseudomonas putida: 4mM citrate and 4mM succinate, for Klebsiella pneumoniae: 1mM aniline and 2mM aniline. Furthermore, all isolates could degrade aniline, 2-chloroaniline, 3-chloroaniline but not degrade 3,4-dichloroaniline.