Department of Environmental Science and Engineering, Xiangtan University, Xiangtan 411105, PR China.
Department of Environmental Science and Engineering, Xiangtan University, Xiangtan 411105, PR China.
Bioresour Technol. 2015 Aug;190:307-14. doi: 10.1016/j.biortech.2015.04.024. Epub 2015 Apr 11.
Removal of ammonium (NH4(+)-N) by microalgae has evoked interest in wastewater treatment, however, the detailed mechanisms of ammonium assimilation remain mysterious. This study investigated the effects of NH4(+)-N concentration on the removal and biotransformation efficiency by Chlorella vulgaris F1068, and explored the mechanisms by (15)N isotope fractionation and proteome approaches. The results showed NH4(+)-N was efficiently removed (84.8%) by F1068 at 10mgL(-1) of NH4(+)-N. The isotope enrichment factor (ε=-2.37±0.08‰) of (15)N isotope fractionation revealed 47.6% biotransformation at above condition, while 7.0% biotransformation at 4mgL(-1) of NH4(+)-N (ε=-1.63±0.06‰). This was due to the different expression of glutamine synthetase, a key enzyme in ammonium assimilation, which was up-regulated 6.4-fold at proteome level and 18.0-fold at transcription level. The results will provide a better mechanistic understanding of ammonium assimilation by microalgae and this green technology is expected to reduce the burden of NH4(+)-N removal for municipal sewage treatment plants.
微藻去除氨（NH4(+)-N）在废水处理中引起了关注，然而，氨同化的详细机制仍然神秘。本研究通过小球藻 F1068 研究了 NH4(+)-N 浓度对去除和生物转化效率的影响，并通过 (15)N 同位素分馏和蛋白质组学方法探讨了其机制。结果表明，F1068 在 10mgL(-1)的 NH4(+)-N 下可有效去除（84.8%）NH4(+)-N。（15）N 同位素分馏的同位素富集因子（ε=-2.37±0.08‰）表明，在上述条件下有 47.6%的生物转化，而在 4mgL(-1)的 NH4(+)-N 下仅有 7.0%的生物转化（ε=-1.63±0.06‰）。这是由于在氨同化中起关键作用的谷氨酰胺合成酶的不同表达所致，其在蛋白质组水平上调了 6.4 倍，在转录水平上调了 18.0 倍。这些结果将为微藻同化氨的机制提供更好的理解，并有望减轻城市污水处理厂 NH4(+)-N 去除的负担。
