Proteomics reveals the enhancing mechanism for eliminating toxic hydroxylamine from water by nanocompartments containing hydroxylamine oxidase.

Hydroxylamine (NHOH) is a potentially toxic pollutant when it is present in water, as it can damage both bacteria and the human body. It is still difficult to eliminate the toxic NHOH in water. Here, we showed that the model bacterium (Escherichia coli) with nanocompartments encapsulated with hydroxylamine oxidase (HAO) can remove NHOH from water. In addition, the removal efficiency of NHOH by genetically modified bacteria (with HAO-nanocompartments) was 3.87 mg N L h, and that of wild-type bacteria (without HAO-nanocompartments) was only 1.86 mg N L h. Label-free quantitative proteomics indicated that the nanocompartments containing HAO enhanced bacterial activity by inducing the up-regulation of proteins involved in stress and stimulus responses, and decreased their intracellular NHOH concentration. Moreover, the synthesis of proteins involved in energy metabolism, gene expression, and other processes in bacterial was enhanced under hydroxylamine stress, and these changes increased the resistance of bacterial to NHOH. This work can aid our understanding of the toxic effects of NHOH on bacteria as well as the development of new approaches to eliminate NHOH in water.