Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Chemical Engineering, Ocean and Life Sciences, Panjin Campus, Dalian University of Technology, China; Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, China, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
College of Engineering, Peking University, Beijing 100871, China.
Sci Total Environ. 2024 Nov 15;951:175482. doi: 10.1016/j.scitotenv.2024.175482. Epub 2024 Aug 14.
The application of manganese-oxidizing bacteria (MnOB) to produce manganese oxides (MnOx) has been widely studied, but often overlooking the concurrent formation of MnCO. In this study, we found Ca plays a crucial role in controlling Mn(II) removal in the bacterium Aurantimonas sp. HBX-1. Under conditions with 6.8 mM Ca and without adding Ca, 100 μM Mn(II) was removed by 96.96 % and 38.28 % within 8 days, respectively. X-ray photoelectron spectroscopy (XPS) showed that adding Ca increased the average oxidation state (AOS) of the solid products from 2.05 to 2.37. X-ray absorption fine structure (XAFS) analysis revealed the product proportions as follows: under Ca-supplemented condition, the ratio of MnOx (1 < x ≤ 2) to MnCO₃ was 52 % to 28.1 %, while under Ca-free condition, the ratio shifted to 4.6 % for MnOx (1 < x ≤ 2) and 55.2 % for MnCO₃. Urease activity assay and proteomic analysis confirmed the expression of urease and carbonic anhydrase, leading to the formation of MnCO. Additionally, animal heme peroxidase (AHP) in strain HBX-1 was found to be responsible for Mn(II) oxidation through superoxide production, with Ca addition promoting its expression level. Given the widespread presence of Ca in wastewater, its potential impact on the biogeochemical Mn(II) cycle driven by bacteria should be reconsidered.
锰氧化菌（MnOB）在产生氧化锰（MnOx）方面的应用已得到广泛研究，但往往忽略了同时形成的 MnCO。在本研究中，我们发现 Ca 在控制 Aurantimonas sp. HBX-1 中 Mn(II)去除方面起着关键作用。在有 6.8 mM Ca 和不加 Ca 的条件下，100 μM Mn(II)分别在 8 天内被去除了 96.96%和 38.28%。X 射线光电子能谱（XPS）表明，添加 Ca 使固体产物的平均氧化态（AOS）从 2.05 增加到 2.37。X 射线吸收精细结构（XAFS）分析表明产物的比例如下：在添加 Ca 的条件下，MnOx（1<x≤2）与 MnCO₃的比例为 52%至 28.1%，而在无 Ca 的条件下，MnOx（1<x≤2）的比例变为 4.6%，MnCO₃的比例变为 55.2%。脲酶活性测定和蛋白质组学分析证实了脲酶和碳酸酐酶的表达，导致 MnCO 的形成。此外，在 HBX-1 菌株中发现动物血红素过氧化物酶（AHP）通过超氧化物的产生负责 Mn(II)氧化，添加 Ca 促进其表达水平。鉴于 Ca 在废水中的广泛存在，应该重新考虑其对细菌驱动的生物地球化学 Mn(II)循环的潜在影响。
