Air Force Engineering and Services Center, Tyndall Air Force Base, Florida 32403-6001, and Department of Microbiology and Biocatalysis Research Group, University of Iowa, Iowa City, Iowa 52242.
Appl Environ Microbiol. 1991 Mar;57(3):812-9. doi: 10.1128/aem.57.3.812-819.1991.
A Moraxella strain grew on p-nitrophenol with stoichiometric release of nitrite. During induction of the enzymes for growth on p-nitrophenol, traces of hydroquinone accumulated in the medium. In the presence of 2,2'-dipyridyl, p-nitrophenol was converted stoichiometrically to hydroquinone. Particulate enzymes catalyzed the conversion of p-nitrophenol to hydroquinone in the presence of NADPH and oxygen. Soluble enzymes catalyzed the conversion of hydroquinone to gamma-hydroxymuconic semialdehyde, which was identified by high-performance liquid chromatography (HPLC)-mass spectroscopy. Upon addition of catalytic amounts of NAD, gamma-hydroxymuconic semialdehyde was converted to beta-ketoadipic acid. In the presence of pyruvate and lactic dehydrogenase, substrate amounts of NAD were required and gamma-hydroxymuconic semialdehyde was converted to maleylacetic acid, which was identified by HPLC-mass spectroscopy. Similar results were obtained when the reaction was carried out in the presence of potassium ferricyanide. Extracts prepared from p-nitrophenol-growth cells also contained an enzyme that catalyzed the oxidation of 1,2,4-benzenetriol to maleylacetic acid. The enzyme responsible for the oxidation of 1,2,4-benzenetriol was separated from the enzyme responsible for hydroquinone oxidation by DEAE-cellulose chromatography. The results indicate that the pathway for biodegradation of p-nitrophenol involves the initial removal of the nitro group as nitrite and formation of hydroquinone. 1,4-Benzoquinone, a likely intermediate in the initial reaction, was not detected. Hydroquinone is converted to beta-ketoadipic acid via gamma-hydroxymuconic semialdehyde and maleylacetic acid.
一株莫拉氏菌能够以化学计量的方式将亚硝酸盐从对硝基苯酚中释放出来。在诱导对硝基苯酚生长的酶时，痕量的对苯二酚在培养基中积累。在 2,2'-联吡啶的存在下，对硝基苯酚被转化为对苯二酚。在 NADPH 和氧气的存在下，颗粒状酶将对硝基苯酚转化为对苯二酚。可溶性酶在 NADPH 和氧气的存在下将对苯二酚转化为γ-羟基粘康酸半醛，这通过高效液相色谱（HPLC）-质谱法得到了鉴定。在添加催化量的 NAD 后，γ-羟基粘康酸半醛被转化为β-酮己二酸。在丙酮酸和乳酸脱氢酶的存在下，需要底物量的 NAD，并且γ-羟基粘康酸半醛被转化为马来酸乙酸，这通过 HPLC-质谱法得到了鉴定。当反应在铁氰化钾存在下进行时，也得到了类似的结果。从对硝基苯酚生长细胞制备的提取物还含有一种酶，该酶催化 1,2,4-苯三醇氧化为马来酸乙酸。负责 1,2,4-苯三醇氧化的酶通过 DEAE-纤维素色谱法与负责对苯二酚氧化的酶分离。结果表明，对硝基苯酚生物降解的途径涉及最初将硝基基团作为亚硝酸盐去除，并形成对苯二酚。初始反应中的可能中间体 1,4-苯醌未被检测到。对苯二酚通过γ-羟基粘康酸半醛和马来酸乙酸转化为β-酮己二酸。
