Rhodobacter sp. NP25b菌株缺氧降解壬基酚聚氧乙烯醚的研究

从城市污水处理厂活性污泥中分离得到一株能够在缺氧条件下以壬基酚聚氧乙烯醚(NPEOs)为惟一碳源和能源生长的菌株NP25b.经生理生化鉴定和16S rRNA基因序列分析,该菌株属于红细菌属(Rhodobacter sp.),对该菌株降解NPEOs的特性进行了研究.结果表明,在缺氧条件下,菌株NP25b在7 d内对初始底物浓度为400 mg/L NPEOs的降解率可达84%.利用液相色谱-质谱(LC-MS)和气相色谱-质谱(GC-MS)对NPEOs降解中间产物进行了分析,结果表明,主要降解产物为短链NPEOs和壬基酚聚氧乙烯醚乙酸(NPECs),其中包括具有较强内分泌干扰效应的NP1EO.该菌株能够代谢含有疏水基团的聚氧乙烯醚类表面活性剂,例如辛基酚聚氧乙烯醚和脂肪醇聚氧乙烯醚.推测菌株NP25b降解NPEOs是通过乙氧基(EO)链末端氧化后逐步切割完成的.

Study on anoxic degradation of nonylphenol polyethoxylates by Rhodobacter sp. strain NP25b

A pure strain growing with nonylphenol polyethoxylates (NPEOs) as the only source of carbon and energy under anoxic condition was isolated from wastewater treatment plant via enrichment and cultivation. This strain belongs to Rhodobacter sp. according to its physiological-biochemical identification and 16S rRNA gene sequence analysis. With initial concentration of 400 mg/L, the degradation rate of NPEOs was 84% within 7 days. Biodegradation intermediates were monitored by LC-MS and GC-MS, which demonstrated that the main biodegradation products were NPEOs oligomers with shorter ethylene oxide (EO) chain and its corresponding carboxyl products (NPECs). This bacterium also metabolized other polyethoxylated surfactants containing a hydrophobic moiety such as alcohol ethoxylates and octylphenol polyethoxylates. Based on these observations, the biodegradation of NPEO in this study would proceed mainly according to the gradual shortening of EO chain accompanied with oxidation of the terminal side.