一株能同时降解邻苯二甲酸二丁酯(DBP)和氰戊菊酯真菌的分离、鉴定及降解特性的初步研究

采用富集培养法从农田土壤中筛选出1株可同时降解邻苯二甲酸二丁酯(DBP)和氰戊菊酯的真菌DY4,经形态、生理生化特征及26S r DNA序列分析,初步鉴定为地霉属(Geotrichum sp.)霉菌,并在纯培养条件下研究了该菌株的最优降解条件和降解特性.结果表明,菌株DY4可利用DBP或氰戊菊酯作为唯一碳源,DBP、氰戊菊酯单一存在时,7 d对50 mg·L-1DBP的降解率(84.13%)高于氰戊菊酯(37.07%)的;DBP、氰戊菊酯共存时,对DBP的降解率明显降低,可能是农药对微生物的毒害作用所致.正交试验得到菌株DY4的最优降解条件为无外加碳源、DBP和氰戊菊酯的初始浓度25 mg·L-1、p H 7.5,在此条件下,7 d对DBP和氰戊菊酯的降解率达到65.36%和55.77%,降解反应符合一级动力学方程模型,两者的半衰期为4.46和6.88 d.

Isolation, identification and degradation characteristics of a dibutyl phthalate and fenvalerate degrading fungal strain

A fungal strain, named DY4, capable of simultaneously degrading dibutyl phthalate (DBP) and fenvalerate was isolated by culture enrichment method from farmland soil. Based on the morphology, physio-biochemical characteristics, and 26S rDNA sequence analysis, strain DY4 was preliminarily identified as Geotrichum sp. The optimal degradation conditions and degradation characteristics of strain DY4 were studied in pure culture incubation assays. The results showed that strain DY4 could utilize DBP and fenvalerate, respectively, as its sole carbon sources. The degradation rate of DBP and fenvalerate with the concentration of 50 mg·L^-1 by strain DY4 was 84.13% and 37.07%, respectively, within 7 days of incubation. However, the degradation of DBP was significantly reduced when DBP and fenvalerate coexisted, which might be attributed to the toxicity of fenvalerate (as pesticide) on fungus. The optimal degradation conditions were determined by orthogonal test as follows: initial concentration of either DBP or fenvalerate, 25 mg·L^-1; pH 7.5; and without additional carbon source. Under these conditions, the degradation rate of DBP and fenvalerate was 65.36% and 55.77%, respectively. Moreover, the degradation followed first-order kinetics and the half time (t_1/2) of DBP and fenvalerate were 4.46 and 6.88 d, respectively.