The genetic determinants of 4-chloro-2-nitrophenol degradation in Cupriavidus sp. strain NyZ417

摘要

4-chloro-2-nitrophenol (4C2NP) is a typical chlorinated nitroaromatic pollutant and its environmental fate is of great concern due to its mutagenic and carcinogenic properties. So far, neither genes nor enzymes responsible for 4C2NP biodegradation have been elucidated. Here, a new 4C2NP degrader NyZ417 was isolated from the activated sludge collected from a wastewater treatment plant of China and identified as a member within Cupriavidus genus according to its 16S rRNA gene sequence analysis. Cupriavidus sp. strain NyZ417 utilized 4C2NP as the sole of nitrogen source for its growth in the presence of additional carbon source. The degradation of 4C2NP by strain NyZ417 was confirmed via an oxidative pathway and induced by substrate itself. For the elucidation of molecular mechanism of 4C2NP degradation in this newly isolated degrader, a monooxygenase encoding gene onpA(NyZ417) retrieved from its complete genome was confirmed to be involved in 4C2NP biotransformation. Resting cells expressing OnpA(NyZ417) depleted 4C2NP completely with stoichiometric formation of 4-chlorocatechol. This study not only elucidated a functional gene for 4C2NP degradation but also would lay a solid foundation for designing approaches for clean-up of 4C2NP residues in the environment.