双菌种协同代谢酚类化合物的机制研究

Co-metabolism of Dual Culture in the Degradation of Phenolic Compounds

以恶臭假单胞菌和热带假丝酵母为对象,进行了苯酚、间甲酚和4-氯酚的生物降解实验,研究了2种菌的纯培养和混合培养方式下3种酚的降解特性和代谢机制.结果表明,当苯酚、间甲酚和4-氯酚的初始浓度分别为100、50和60 mg.L-1时,相对于纯培养,混合培养的动力学常数k的绝对值分别提高了19.0%、2.6%和46.4%.苯酚羟化酶和邻苯二酚1,2-双加氧酶的活性测定表明,2种菌降解苯酚均经过邻位裂解途径.采用液相色谱(HPLC)和液质联用技术(LC-MS)进一步分析表明,混合培养中热带假丝酵母降解苯酚和4-氯酚分别积累的中间代谢物顺,顺-粘糠酸和4-羧基亚甲基丁-2-烯-4-交脂,以及降解间甲酚过程中积累的中间代谢物二羟基苯甲酸、3-羟基顺,顺粘糠酸和3-羰基己二酸能够被恶臭假单胞菌协同代谢,从而促进3种酚的降解.

The biodegradation of phenol,m-cresol and 4-chlorophenol by the pure and mixed culture of Pseudomonas putida and Candida tropicalis was investigated.The results showed that,with the initial concentrations of 100,50 and 60 mg·L-1for phenol,m-cresol and 4-chlorophenol,respectively,and an increase in the absolute value of the kinetic constant k of 19.0%,2.6% and 46.4% for the degradation of phenol,m-cresol and 4-chlorophenol,respectively,was reached by dual culture compared with pure culture.The activity assays of phenol hydroxylase and catechol 1,2-dioxygenase demonstrated phenol was degraded via the ortho-cleavage pathway in both of the two species.Further experiments via high performance liquid chromatography（HPLC） and liquid chromatography-mass spectrometry techniques（LC-MS） suggested the degradation of three phenolic compounds could be accelerated due to co-metabolism by Pseudomonas putida of cis,cis-muconic acid,and 4-carboxymethylenebut-2-en-4-olide accumulated in phenol and 4-chlorophenol degradation,respectively,3,4-dihydroxybenzoic acid,2-maleylacetate,and 3-oxoadipate in the degradation of m-cresol by Candida tropicalis in dual culture.