Paulo Ana M S, Aydin Rozelin, Dimitrov Mauricio R, Vreeling Harm, Cavaleiro Ana J, García-Encina Pedro A, Stams Alfons J M, Plugge Caroline M
Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
Department of Chemical Engineering and Environmental Technology, University of Valladolid, Calle Dr. Mergelina s/n, 47011, Valladolid, Spain.
Appl Microbiol Biotechnol. 2017 Jun;101(12):5163-5173. doi: 10.1007/s00253-017-8212-x. Epub 2017 Mar 15.
The surfactant sodium lauryl ether sulfate (SLES) is widely used in the composition of detergents and frequently ends up in wastewater treatment plants (WWTPs). While aerobic SLES degradation is well studied, little is known about the fate of this compound in anoxic environments, such as denitrification tanks of WWTPs, nor about the bacteria involved in the anoxic biodegradation. Here, we used SLES as sole carbon and energy source, at concentrations ranging from 50 to 1000 mg L, to enrich and isolate nitrate-reducing bacteria from activated sludge of a WWTP with the anaerobic-anoxic-oxic (A/O) concept. In the 50 mg L enrichment, Comamonas (50%), Pseudomonas (24%), and Alicycliphilus (12%) were present at higher relative abundance, while Pseudomonas (53%) became dominant in the 1000 mg L enrichment. Aeromonas hydrophila strain S7, Pseudomonas stutzeri strain S8, and Pseudomonas nitroreducens strain S11 were isolated from the enriched cultures. Under denitrifying conditions, strains S8 and S11 degraded 500 mg L SLES in less than 1 day, while strain S7 required more than 6 days. Strains S8 and S11 also showed a remarkable resistance to SLES, being able to grow and reduce nitrate with SLES concentrations up to 40 g L. Strain S11 turned out to be the best anoxic SLES degrader, degrading up to 41% of 500 mg L. The comparison between SLES anoxic and oxic degradation by strain S11 revealed differences in SLES cleavage, degradation, and sulfate accumulation; both ester and ether cleavage were probably employed in SLES anoxic degradation by strain S11.
表面活性剂月桂醇聚醚硫酸酯钠（SLES）广泛用于洗涤剂配方中，并且常常最终进入污水处理厂（WWTPs）。虽然对SLES的好氧降解已有充分研究，但对于该化合物在缺氧环境中的归宿，如污水处理厂的反硝化池，以及参与缺氧生物降解的细菌却知之甚少。在此，我们使用SLES作为唯一碳源和能源，浓度范围为50至1000 mg/L，采用厌氧-缺氧-好氧（A/O）概念从污水处理厂的活性污泥中富集和分离硝酸盐还原菌。在50 mg/L的富集培养物中，丛毛单胞菌属（50%）、假单胞菌属（24%）和嗜环烷菌属（12%）的相对丰度较高，而在1000 mg/L的富集培养物中假单胞菌属（53%）成为优势菌属。从富集培养物中分离出嗜水气单胞菌菌株S7、施氏假单胞菌菌株S8和硝基还原假单胞菌菌株S11。在反硝化条件下，菌株S8和S11在不到1天的时间内降解了500 mg/L的SLES，而菌株S7则需要超过6天。菌株S8和S11还表现出对SLES的显著抗性，能够在SLES浓度高达40 g/L的情况下生长并还原硝酸盐。菌株S11被证明是最佳的缺氧SLES降解菌，能够降解高达500 mg/L的41%。菌株S11对SLES的缺氧降解与好氧降解的比较揭示了SLES裂解、降解和硫酸盐积累方面的差异；菌株S11在缺氧降解SLES时可能同时采用了酯键和醚键的裂解方式。
