Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Ocean Science and Technology, Panjin Campus, Dalian University of Technology, China.
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Ocean Science and Technology, Panjin Campus, Dalian University of Technology, China.
Environ Res. 2023 Dec 15;239(Pt 1):117373. doi: 10.1016/j.envres.2023.117373. Epub 2023 Oct 11.
Biological Mn(II) removal usually involves adsorption and precipitation of Mn(II) in the form of various minerals. Manganese oxides (MnO) formation through the activity of Mn(II) oxidation bacteria (MnOB) contributes to the majority of Mn(II) removal. However, whether other bacterial-mediated pathway could couple or competitive with Mn(II) oxidation during Mn(II) removal is scarcely reported. In this study, we reported a competitive Mn(II) removal occurred in nutrient-rich condition during the indirect Mn(II) oxidation of Lysinibacillus sp. MHQ-1, i.e., microbially-induced carbonate precipitation (MICP). In the presence of 1 mM Mn(II), 39.4% of free Mn(II) converted to MnCO(s) quickly within 100 h, and then 11.6% of initial Mn(II) slowly oxidized to MnO within 442 h. The urease activity assay and the genome sequencing confirmed the existence of urease and the absence of Mn(II)-oxidizing enzymes in the genome of strain MHQ-1. The urease catalyzed the formation of carbonate ion that reacts with Mn(II) and the formed ammonia raises the pH to initiate indirect Mn(II) oxidation. Genome survey suggests the urease widely exists in various Mn(II)-oxidizing bacteria (MnOB), emphasizing the importance to reconsider the composition, stability and environmental effects of biological Mn(II) removal products in nutrient-rich environment.
生物 Mn(II)去除通常涉及以各种矿物形式吸附和沉淀 Mn(II)。锰氧化物（MnO）的形成是通过 Mn(II)氧化菌（MnOB）的活性促成的，这是 Mn(II)去除的主要原因。然而，其他细菌介导的途径是否可以与 Mn(II)氧化耦合或竞争，在 Mn(II)去除过程中鲜有报道。在本研究中，我们报道了在 Lysinibacillus sp. MHQ-1 间接氧化 Mn(II)过程中，在富营养条件下发生了竞争性的 Mn(II)去除，即微生物诱导碳酸钙沉淀（MICP）。在 1mM Mn(II)存在的情况下，39.4%的游离 Mn(II)在 100h 内迅速转化为 MnCO(s)，然后 11.6%的初始 Mn(II)在 442h 内缓慢氧化为 MnO。脲酶活性测定和基因组测序证实了菌株 MHQ-1 基因组中存在脲酶而不存在 Mn(II)氧化酶。脲酶催化碳酸根离子的形成，与 Mn(II)反应，形成的氨会提高 pH 值，从而引发间接 Mn(II)氧化。基因组调查表明，脲酶广泛存在于各种 Mn(II)氧化菌（MnOB）中，这强调了在富营养环境中重新考虑生物 Mn(II)去除产物的组成、稳定性和环境影响的重要性。
