Biodegradation of 4-chloronitrobenzene by biochemical cooperation between Sphingomonas sp. strain CNB3 and Burkholderia sp. strain CAN6 isolated from activated sludge

Two bacterial strains were isolated from activated sludge by using 4-chloronitrobenzene (4-CB) as the sole source of carbon for enrichment. One of the isolates was identified as Sphingomonas sp. strain CNB3 and the other as Burkholderia sp. strain CAN6, mainly through morphological and physiological characteristics and 16S rRNA gene sequence analysis. Sphingomonas sp. strain CNB3 could transform 4-CB to 4-chloroaniline, which accumulated in the medium. Burkholderia sp. strain CAN6 could transform 4-chloroaniline but not 4-CB. The co-culture of Sphingomonas sp. strain CNB3 and Burkholderia sp. strain CAN6 could degrade 4-CB completely by the biochemical cooperation of two strains to overcome the degradative limitations of each species alone. In addition, the biochemical pathway of 4-chloroaniline transformation by Burkholderia sp. strain CAN6 was proposed based on the determined related enzyme activities. The results suggested that 4-chloroaniline was completely transformed via the ortho-cleavage and modified ortho-cleavage pathways.

► Individual Sphingomonas sp. strain CNB3 could transform 4-CNB to 4-chloroaniline.
► Individual Burkholderia sp. strain CAN6 could transform 4-chloroaniline.
► Biochemical cooperation of CNB3 and CAN6 could completely degrade 4-CNB.