Reductive dehalogenation mediated initiation of aerobic degradation of 2-chloro-4-nitrophenol (2C4NP) by Burkholderia sp. strain SJ98

Abstract

Burkholderia sp. strain SJ98 (DSM 23195) was previously isolated and characterized for degradation and co-metabolic transformation of a number nitroaromatic compounds. In the present study, we evaluated its metabolic activity on chlorinated nitroaromatic compounds (CNACs). Results obtained during this study revealed that strain SJ98 can degrade 2-chloro-4-nitrophenol (2C4NP) and utilize it as sole source of carbon, nitrogen, and energy under aerobic conditions. The cells of strain SJ98 removed 2C4NP from the growth medium with sequential release of nearly stoichiometric amounts of chloride and nitrite in culture supernatant. Under aerobic degradation conditions, 2C4NP was transformed into the first intermediate that was identified as p-nitrophenol by high-performance liquid chromatography, LCMS-TOF, and GC-MS analyses. This transformation clearly establishes that the degradation of 2C4NP by strain SJ98 is initiated by "reductive dehalogenation"; an initiation mechanism that has not been previously reported for microbial degradation of CNAC under aerobic conditions.

The Gene Cluster for para -Nitrophenol Catabolism Is Responsible for 2-Chloro-4-Nitrophenol Degradation in Burkholderia sp. Strain SJ98

“…strain SJ98 that is different from those of all other 2C4NP utilizers was characterized at the genetic and biochemical levels. To our surprise, chloro-1,4-benzoquinone (CBQ) and CHQ, rather than PNP, 4-nitrocatechol (4-NC), and BT, as previously proposed (13), were identified during 2C4NP degradation. On the other hand, the pnpABA1CDEF cluster in a signal operon was proved to be also responsible for 2C4NP degradation by this strain, in addition to PNP degradation.…”

“…Previously, 2C4NP degradation by strain SJ98 was reported to be initiated by reductive dechlorination with the formation of PNP, which was further degraded via a BT pathway (Fig. 8B) (13). In this study, an initial bioinformatic analysis did not identify genes encoding the potential reductive dehalogenase or two-component PNP monooxygenase in its draft genome.…”

“…To date, four pure bacterial cultures have been isolated on the basis of the ability to utilize 2C4NP as a sole carbon and energy source (1,(12)(13)(14), and three different pathways based on different intermediates present during its degradation have been proposed. Rhodococcus imtechensis RKJ 300 (14) and Burkholderia sp.…”

“…strain RKJ 800 (12) were reported to degrade 2C4NP via the HQ pathway, whereas Burkholderia sp. strain SJ98 degraded 2C4NP with the formation of PNP, which was further degraded via the BT pathway (13,15). On the other hand, Arthrobacter sp.…”

A Two-Component para -Nitrophenol Monooxygenase Initiates a Novel 2-Chloro-4-Nitrophenol Catabolism Pathway in Rhodococcus imtechensis RKJ300

“…So far, several strains able to degrade chloronitrophenols have been isolated, including the 2C4NP-degrading strains Burkholderia sp. strain SJ98 (2), Burkholderia sp. strain RKJ800 (3), Rhodococcus imtechensis RKJ300 (4), and Arthrobacter sp.…”