球形红细菌降解PNP的不同因素影响及代谢机理

Effects of Different Factors on PNP Degradation by Rhodobacter sphaeroides and Metabolic Mechanisms

通过拟合Haldane动力学方程,分析球形红细菌(Rhodobacter sphaeroides)H菌株降解对硝基苯酚(PNP)的生长动力学特性;考察营养因素(碳源、金属离子和NaCl浓度)对H菌株降解PNP的影响以及H菌株对酚类物质的底物广谱性,并对H菌株降解PNP的代谢机理进行推测。结果表明,H菌株降解PNP的生长动力学符合Haldane模型(R2=0.9990);H菌株降解PNP的最适碳源和金属离子分别是苹果酸和Ca^2+,NaCl浓度耐受值为20 mg·L^-1;酚类物质中邻苯二酚对PNP降解影响最大;利用高效液相色谱-质谱联用仪(HPLC-MC)对菌株代谢PNP的产物进行分析,发现中间产物主要为对苯二酚(HQ)、4-羟基粘糠酸半醛(4-HS)和马来酰胺乙酸(MA),同时酶活性分析表明底物HQ在粗酶液中对苯二酚1,2-双加氧酶作用下生成4-HS,由此推测H菌株可能利用的是对苯二酚代谢途径。

The growth kinetics of PNP degradation by Rhodobacter sphaeroides H strain was analyzed by fitting the Haldane kinetic equation.The effects of nutrition factors(carbon source,metal ions and NaCl concentration)on the degradation of PNP by H strain and the substrate broad spectrum of phenol by H strain were investigated,and the metabolic mechanism of degradation of PNP by H strain was speculated.Results show that the growth kinetics of H strain degrading PNP conforms to Haldane model(R2=0.9990).The most suitable carbon source and metal ions for degrading PNP by strain H are malic acid and Ca^2+,respectively,and the tolerance value of NaCl concentration is 20 mg·L^-1.Influence of the catechol on PNP degradation is the greatest among phenols.High performance liquid chromatography-mass spectrometry(HPLC-MC)was used to analyze the metabolites of PNP produced by the strain.It is found that the intermediate products are mainly hydroquinone(HQ),4-hydroxymuconic acid semialdehyde(4-HS)and maleamic acid(MA).Meanwhile,enzyme activity analysis shows that the substrate HQ produces 4-HS under the action of hydroquinone 1,2-dioxygenase in crude enzyme solution,thus suggesting that strain H may utilize the metabolic pathway of hydroquinone.