苯并(a)芘及其代谢产物的连续降解研究

在以驯化过的芽孢杆菌(BA-07)降解BaP的过程中,鉴定出2个BaP的未开环代谢产物顺式-4,5-二氢-4,5-二醇-BaP(cis-BP4,5-dihydrodiol)和顺式-7,8-二氢-7,8-二醇-BaP(cis-BP7,8-dihydrodiol).由于该产物对微生物有一定毒性,所以难于进一步降解.为提高BaP降解的同时,降低cis-BP4,5-dihydrodiol和cis-BP7,8-dihydrodiol的累积,对2种降解方法(即单纯用BA07降解和运用高锰酸钾与BA-07耦合的方法降解)进行了比较,并且优化了连续降解的参数.结果表明,①对BaP及其代谢产物的连续降解,化学氧化与微生物耦合(高锰酸钾与BA-07)的降解效果明显好于单纯利用微生物(细菌BA-07)的降解;②在同一时间取样,cis-BP4,5-dihydrodiol的残留率均高于cis-BP7,8-dihydrodiol;③当BaP的浓度为40μg/mL,培养基的最佳pH为7.0,以琥珀酸钠为共代谢底物,可以显著提高BaP降解率,降低cis-BP 4,5-dihydrodiol和cis-BP7,8-dihydrodiol的累积.同时提出了化学氧化与微生物协同的方法可以有效促进环境中持久有机污染物的连续降解.

Study on Continued Degradation of BaP and its Metabolites

Two metabolites, cis-BP4, 5-dihydrodiol and cis-BP7, 8-dihydrodiol, were identified by high-performance liquid chromatography (HPLC) during the degradation of BaP by Bacillus-07 (BA-07). The two metabolites were hardly further metabolized for their toxicity to microorganism. To promote degradation of BaP and decrease accumulation of cis-BP4, 5-dihydrodiol and cis-BP7, 8-dihydrodiol, two methods (degradation only by BA-07, degradation by coupling the BA-07 and KMnO4) were compared. In addition, parameters of continued degradation of BaP and the two metabolites were optimized under the experiment conditions. The results showed that (1)the method of coupling the chemical oxidation and biodegradation (BA-07 and KMnO4) was better than only biodegradation (BA-07); (2) residue rate of cis-BP4, 5-dihydrodiol was higher than that of cis-BP7, 8-dihydrodiol when the samples were determined in the same time; (3)the effect of continued degradation was the best when the initial concentration of BaP was 40 microg/mL, pH value of the culture was 7.0, co-metabolic substrates was sodium succinate. Meanwhile, it was put forward that the method of coupling the chemical oxidation and biodegradation was effective on continued degradation of persistent organic contaminants in the environment.