[A novel metabolism pathway for the biodegradation of chloroanilines]

Up to date, p-chloroaniline was reported to be biodegraded only through ortho-or modified ortho-cleavage pathway. In this paper, the intermediates of p-chloroaniline metabolized by strain Diaphorobacter PCA039 were analyzed and identified by HPLC and LC/MS methods. The results showed that intermediates such as 4-chlorocatechol, 2-hydroxy-5-chloromuconic semialdehyde, 5-chloro-4-oxalocrotonate, 5-chloro-2-oxo-4-hydroxypentanote, chloro-acetate were formed and consumed in order during the degradation of p-chloroaniline by strain Diaphorobacter PCA039.These compounds are the intermediates of a typical meta-cleavage pathway. In addition, strain Diaphorobacter PCA039 could produce the induced catechol 2, 3-dioxygenase when it grows on p-chloroaniline as sole carbon, nitrogen and energy sources, and use the intermediates of the meta-cleavage pathway such as catechol, 4-chlorocatechol, 2-hydroxy-5-chloromuconic semialdehyde as sole carbon and energy sources. Combining its physiological and biochemical properties and the results of LC/MS analysis, it was concluded that strain Diaphorobacter PCA039 could also degrade p-chloroaniline through meta-cleavage pathway as Fig. 4, which is a new pathway for the biodegradation of p-chloroaniline. It is significant to the study of biodegradation, metabolic mechanism, properties of the enzymes and the expression and regulation of the genes involved in the degradation of p-chloroaniline.