邻苯二甲酸二丁酯降解菌的筛选及降解条件研究

Screening and the degradation conditions of DBP-degrading bacterium

目的筛选并鉴定一株能以邻苯二甲酸二丁酯(DBP)为唯一碳源生长的菌株,探索利用该菌株降解DBP的最优条件。方法在基础无机盐培养基中加入DBP,将土壤浸出液接种于该培养基,筛选得到目标菌株。通过菌落表型、透射电镜、PCR等方法对该菌株进行形态、生理生化特征鉴定及16Sr DNA序列分析。将目标菌株接种至p H值不同的上述培养基,于不同温度下进行培养,通过测定DBP残留和细菌含量确定最佳p H值和温度。结果通过只添加DBP作为微生物的碳源,富集培养得到一株菌株L6。通过形态、生理生化及16Sr DNA序列分析,将其鉴定为甲基杆菌属(Methylobacterium sp.)。通过优化得到DBP最佳降解条件为p H=7,温度=30℃。在最佳降解条件下,菌株L6在120 h内对含800 mg/L DBP的降解率达到85.0%。结论菌株L6对DBP有较强的降解能力,最佳降解条件为p H=7、温度=30℃,可考虑应用于DBP污染的生物修复试验。

Objective To identify a strain screen which utilize dibutyl phthalate （DBP） as the sole carbon source and to explore the optimal conditions for the degradation of DBP. Methods The solid leachate was inoculated in minimal salt medium （MSM） supplemented with DBP as the sole carbon and energy source to isolate the targeted strain. The strain was identified through colony phenotype, transmission electron microscope and 16SrDNA gene sequence analysis. The targeted strain was inoculated to the above medium with different pH and temperature. The optimal temperature and pH of the microbial degradation of DBP were studied with determination of the DBP residue and bacterial biomass. Results One bacterial strain named L6 was isolated from the solid with adding DBP as the sole carbon source. Based on its morphology, physiochemical characteristics, and 16SrDNA sequence, the strain was identified as Methylobacterium sp. The optimal pH and temperature for its biodegradation activities were 7 and 30℃, respectively. The targeted strain could degrade 85% of 800 mg/L DBP within 120 hours. Conclusion Based on the high removal rate, the isolated Methylobacterium sp. L6 has a potential for bioremediation technology of DBP pollution.