Evaluating metabolic potential of Thauera sp. M9 for the transformation of 4-chloroaniline (4-CA)

Thauera sp. M9, was isolated after enrichment of microbial diversity in nitrogen free mineral salt medium (NFMSM) supplemented with 300 mg/l of 4-chloroaniline (4-CA). The isolate M9 was able to achieve complete degradation of 300 mg/l 4-CA supplement to NFMSM, after 30 h incubation. In addition to 4-CA, isolate M9 was able to achieve complete degradation of 300 mg/l 3-chloroaniline (3-CA), 21% degradation of 300 mg/l 2-chloroaniline (2-CA), and complete transformation of 50 mg/l of 3, 4-dichloroaniline (3, 4-DCA), was observed only in the presence of 0.02% (w/v) yeast extract (YE) supplement to NFMSM. The presence of catechol 2, 3-dioxygenase (C23O) activity in cell free extract and detection of 4-chlorocatechol (4-CC); 2-hydroxy muconic semialdehyde (2-HMS) in biologically transformed samples by mass spectroscopy (MS) analysis indicated to meta-cleavage of the aromatic ring. A plug flow reactor (PFR) was developed using polyurethane foam (PUF) and refractory brick pieces (RBP) as immobilization matrix. The treatment of simulated effluent supplemented with 300 mg/l 4-CA through PFR, resulted in 88% transformation of 4-CA and 70% lowering of chemical oxygen demand (COD). These observations suggest that Thauera sp. M9 could be a potential inoculum for developing bioremediation protocols for waste rich in chloroanilines (CAs).