Biodegradation of 2-chloro-4-nitrophenol via a hydroxyquinol pathway by a Gram-negative bacterium, Cupriavidus sp. strain CNP-8

Abstract

Cupriavidus sp. strain CNP-8 isolated from a pesticide-contaminated soil was able to utilize 2-chloro-4-nitrophenol (2C4NP) as a sole source of carbon, nitrogen and energy, together with the release of nitrite and chloride ions. It could degrade 2C4NP at temperatures from 20 to 40 °C and at pH values from 5 to 10, and degrade 2C4NP as high as 1.6 mM. Kinetics assay showed that biodegradation of 2C4NP followed Haldane substrate inhibition model, with the maximum specific growth rate (μmax) of 0.148/h, half saturation constant (Ks) of 0.022 mM and substrate inhibition constant (Ki) of 0.72 mM. Strain CNP-8 was proposed to degrade 2C4NP with hydroxyquinol (1,2,4-benzenetriol, BT) as the ring-cleavage substrate. The 2C4NP catabolic pathway in strain CNP-8 is significant from those reported in other Gram-negative 2C4NP utilizers. Enzymatic assay indicated that the monooxygenase initiating 2C4NP catabolism had different substrates specificity compared with previously reported 2C4NP monooxygenations. Capillary assays showed that strain CNP-8 exhibited metabolism-dependent chemotactic response toward 2C4NP at the optimum concentration of 0.5 mM with a maximum chemotaxis index of 37.5. Furthermore, microcosm studies demonstrated that strain CNP-8, especially the pre-induced cells, could remove 2C4NP rapidly from the 2C4NP-contaminated soil. Considering its adaptability to pH and temperature fluctuations and great degradation efficiency against 2C4NP, strain CNP-8 could be a promising candidate for the bioremediation of 2C4NP-contaminated sites.Electronic supplementary materialThe online version of this article (10.1186/s13568-018-0574-7) contains supplementary material, which is available to authorized users.

Cathodic reduction characteristics of 2-chloro-4-nitrophenol in microbial electrolysis cell

“…4. A reverse result with Min [3] that the carbon source with different nutrient solution of glucose and sodium acetate can inhibit 2C4NP degradation. Although the degradation efficiency of 2C4NP by adding glucose as a co-substrate wasn't obvious lower than 2C4NP as the only substrate, the degradation rate was significantly reduced by adding sodium acetate.…”

“…On the one hand, the activity of electro-microorganisms was improved. On the other hand, electrons could directly attack 2C4NP adsorbed on the surface of microorganisms through the rapid transfer of microbial coenzymes, causing dechlorination, denitrated, or ring cleavage of 2C4NP [2,3,28]. In the samples of 36 h, the degradation efficiency of 2C4NP attained to more than 92% under the conditions of various applied voltages, while the degradation efficiency of 2C4NP was 85.9% when no voltage was applied.…”

“…Co-metabolism is a relatively unique metabolic method [30][31][32]. Some organic substances which are difficult to biodegrade can be initiated or promoted the degradation of those substances by adding other substances what are easily degraded by microorganisms such as glucose, ethanol, and sodium acetate [3,33]. To study the effect of cometabolism for the biodegradation of 2C4NP by the microbes in the anaerobic MEC cathode chamber, the carbon source with different nutrient solution was added to the reactor: First, 2-chloro-4-nitrophenol as a single matrix nutrient solution (30 mg/L); Second, a common-based nutrient solution with glucose as a primary matrix (wherein 2C4NP was 30 mg/L); Third, sodium acetate as a primary matrix nutrient solution (wherein 2C4NP was 30 mg/L), externally connected DC 0.5 V, and the degradation rate of 2-chloro-4-nitrophenol with the time was shown in Fig.…”

“…6 and Table S1. Several molecular ion peaks such as its fragments at m/z 142.9475 was 2-chloro-4-aminophenol, and 143.1067 was chlorohydroquinone (CHQ) [2,3,[30][31][32][33][34][35], 141.0528 possibility was γ-hydroxymuconic semialdehyde [33,35] Table S1 indicate that under the coupling of electricity and anaerobic microorganisms, 2C4NP was reduced and assimilated to form many intermediates.…”

“…As a representatives among the chlorinated nitroaromatics, chloronitrophenols (CNPs) are extensively utilized in the fields of synthetic insecticides, fungicides, drugs, dyes, etc [1,2]. The major sources of CNPs in the environment are prevailingly coming from artificial manufacturing and use, or the degradation of their derivatives [3]. 2-chloro-4-nitrophenol (2C4NP) is considered as the commonest isomeride of CNPs that is used for the production of herbicides [4], molluscicides [5] as an intermediate material.…”