Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, School of Environment, Jinan University, Guangzhou 510632, PR China.
Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, School of Environment, Jinan University, Guangzhou 510632, PR China.
Sci Total Environ. 2018 Mar;616-617:117-127. doi: 10.1016/j.scitotenv.2017.10.298. Epub 2017 Nov 4.
Phthalic acid esters (PAEs) are a group of recalcitrant and hazardous organic compounds that pose a great threat to both ecosystem and human beings. A novel endophytic strain YJB3 that could utilize a wide range of PAEs as the sole carbon and energy sources for cell growth was isolated from Canna indica root tissue. It was identified as Bacillus megaterium based on morphological characteristics and 16S rDNA sequence homology analysis. The degradation capability of the strain YJB3 was investigated by incubation in mineral salt medium containing di-n-butyl-phthalate (DBP), one of important PAEs under different environmental conditions, showing 82.5% of the DBP removal in 5days of incubation under the optimum conditions (acetate 1.2g·L, inocula 1.8%, and temperature 34.2°C) achieved by two-step sequential optimization technologies. The DBP metabolites including mono-butyl phthalate (MBP), phthalic acid (PA), protocatechuic acid (PCA), etc. were determined by GC-MS. The PCA catabolic genes responsible for the aromatic ring cleavage of PCA in the strain YJB3 were excavated by whole-genome sequencing. Thus, a degradation pathway of DBP by the strain YJB3 was proposed that MBP was formed, followed by PA, and then the intermediates were further utilized till complete degradation. To our knowledge, this is the first study to show the biodegradation of PAEs using endophyte. The results in the present study suggest that the strain YJB3 is greatly promising to act as a competent inoculum in removal of PAEs in both soils and crops.
邻苯二甲酸酯（PAEs）是一组难降解且具有危害性的有机化合物，对生态系统和人类构成了巨大威胁。从美人蕉根组织中分离到一株新型内生菌株 YJB3，该菌株可以利用多种 PAEs 作为唯一的碳源和能源进行细胞生长。根据形态特征和 16S rDNA 序列同源性分析，该菌株被鉴定为巨大芽孢杆菌。在含有邻苯二甲酸二丁酯（DBP）的无机盐培养基中培养，研究了菌株 YJB3 的降解能力，DBP 是 PAEs 中的一种重要化合物。在最佳条件下（乙酸盐 1.2g·L、接种量 1.8%、温度 34.2°C），经过两步序贯优化技术，菌株 YJB3 在 5 天的孵育期内可去除 82.5%的 DBP。通过 GC-MS 确定了 DBP 的代谢产物，包括邻苯二甲酸单丁酯（MBP）、邻苯二甲酸（PA）、原儿茶酸（PCA）等。通过全基因组测序，挖掘了菌株 YJB3 中负责 PCA 芳香环断裂的 PCA 代谢基因。因此，提出了菌株 YJB3 降解 DBP 的途径，即先形成 MBP，然后是 PA，然后进一步利用中间产物直至完全降解。据我们所知，这是首次利用内生菌研究 PAEs 的生物降解。本研究结果表明，该菌株 YJB3 有望成为土壤和作物中去除 PAEs 的有效接种物。
