4- nitrophenol adaptive degradation

Systematic studies on the degradation of 4-nitrophenol (Spain et al. 1984) showed that the rates of adaptation in a natural system were comparable to those observed in a laboratory test system and were associated with an increase in the number of degrading organisms by up to 1000-fold. 

Several pure cultures isolated from soils degraded nitrophenols (EPA 1985). As in the case of water, adaptation of soil to 4-nitrophenol was a prerequisite for biodegradation the presence of a critical number of degrader microorganisms was necessary for the initiation of biodegradation However, unlike in natural water, the mineralization of low concentrations of 4-nitrophenol proceeds with little or no initial acclimation period (Scow et al. 1986). Addition of specific nutrients from pristine aquifer also resulted in more rapid adaptation (Aelion et al. 1987 Swindoll et al. 1988), and the rate of biodegradation was concentration-dependent (Scow et al. 1986). The biodegradation of... 

The biodegradation of nitrophenols has been studied extensively because of the wide use of pesticides that contain nitrophenyl groups and because the nitrophenols are used as preservatives for leather. Simpson and Evans (42) isolated a Pseudomonas from soil that was able to grow on 4-nitrophenol with concomitant release of nitrite. Based on evidence from simultaneous adaptation studies they proposed that 4-nitrophenol was converted to hydroquinone. Subsequently, Munnecke and Hsieh (28) detected traces of hydroquinone in the medium when cultures of a soil pseudomonad were grown on 4-nitrophenol. They proposed that hydroquinone was hydroxylated to 1,2,4-benzenetriol as the next step in the metabolic pathway but provided no experimental evidence. Nitrite release was detected during the degradation of a wide range of nitrophenols and nitrobenzoates (20) over the next 20 years, but the mechanism of the reaction remained obscure because the enzyme responsible for the initial reaction could not be studied in cell extracts. 

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