Degradation of Phenylurea Herbicides by a Novel Bacterial Consortium Containing Synergistically Catabolic Species and Functionally Complementary Hydrolases

Abstract

Phenylurea herbicides (PHs) are frequently detected as major water contaminants in areas where there is extensive use. In this study, Diaphorobacter sp. strain LR2014-1, which initially hydrolyzes linuron to 3,4-dichloroanaline, and Achromobacter sp. strain ANB-1, which further mineralizes the produced aniline derivatives, were isolated from a linuronmineralizing consortium despite being present at low abundance in the community. The synergistic catabolism of linuron by the consortium containing these two strains resulted in more efficient catabolism of linuron and growth of both strains. Strain LR2014-1 harbors two evolutionary divergent hydrolases from the amidohydrolase superfamily Phh and the amidase superfamily TccA2, which functioned complementarily in the hydrolysis of various types of PHs, including linuron (N-methoxy-N-methyl-substituted), diuron, chlorotoluron, fluomethuron (N,N-dimethyl-substituted), and siduron. These findings show that a bacterial consortium can contain catabolically synergistic species for PH mineralization, and one strain could harbor functionally complementary hydrolases for a broadened substrate range.

Mineralization of the herbicide swep by a two-strain consortium and characterization of a new amidase for hydrolyzing swep

“…More interestingly, though species with in the various genus (such as Variovorax, Sphingomonas and Achromobacter) are capable of mineralizing 3,4-DCA, no species have been reported possessing the 3,4-DCA degradation ability within the genus of Alicycliphilus. Degradation of xenobiotics by the microbial are complicated and rarely completely degraded by a single strain [18]. Most of them need to be completely degraded by the synergistic action of microbial consortium.…”

“…The analysis of swep, its metabolite 3,4-DCA and analogues of swep and 3,4-DCA, were performed by HPLC, the details for which are described as before [18,21].…”

“…Strain SWP-3 was pre-cultured in MSM medium with different substrates (0.3 mM of swep, propanil, chlorpropham, propham, glucose or 4-acetaminophenol) at 30 °C for 12 h, after which total RNA was extracted as the way described before [18]. The RT-qPCR procedure is described in Additional file 1 in detail.…”

“…strain Y57 [17] and Achromobacter sp. strain ANB-1 [18], have been isolated and characterized from various habitats that are capable of mineralizing 3,4-DCA. Eleven genes that responsible for the aniline derivative oxygenation (dcaQTA1A2BR) and catechol ortho-cleavage catabolism (ccdRCFDE) have been also widely reported [16,18].…”

“…strain ANB-1 [18], have been isolated and characterized from various habitats that are capable of mineralizing 3,4-DCA. Eleven genes that responsible for the aniline derivative oxygenation (dcaQTA1A2BR) and catechol ortho-cleavage catabolism (ccdRCFDE) have been also widely reported [16,18]. However, to date, no studies on the biotransformation of swep have been reported and enzymes involving in the degradation of swep have also not been characterized previously.…”