Tu Guangyuan, Ou Chunyu, Liao Qi, Zhang Xiaoming, Hou Shuangle, Yu Lin, Li Kun, Yang Sen, Li Qi, Yang Weichun, Li Qingzhu, Si Mengying, Yang Zhihui
School of Metallurgy and Environment, Central South University, Changsha, 410083, Hunan, PR China.
School of Metallurgy and Environment, Central South University, Changsha, 410083, Hunan, PR China; Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, Hunan, PR China.
Environ Res. 2025 Jun 15;275:121450. doi: 10.1016/j.envres.2025.121450. Epub 2025 Mar 20.
The oxidation of Cr(III) to Cr(VI) plays a critical role in the biogeochemical cycling of chromium, particularly in soils. This study investigated Cr(III) oxidation mediated by three strains of manganese-oxidizing bacteria: Pseudomonas putida MnB1, Brevundimonas diminuta MnO-2, and Pannonibacter phragmitetus MnO-3 through generating biogenic manganese oxides (BioMnO). The MnB1-generated BioMnO exhibited superior Cr(III) oxidation efficiency (82.00 %) compared with the BioMnO generated by MnO-2 (2.50 %) and MnO-3 (3.26 %). Structural characterization (XRD, SEM, TEM, XPS) demonstrated that MnB1-derived BioMnO possessed three distinctive structural features: a disordered layered structure, abundant oxygen vacancies, and elevated Mn(III/IV) ratios, which synergistically enhanced active site availability for Cr(III) oxidation. Notably, only the MnB1 system effectively oxidized slightly soluble Cr(III) forms (e.g., Cr(OH), CrFe(OH)), with these structural advantages directly accounting for its superior efficiency (82.00 %). Kinetic analysis showed that the Cr(III) oxidation followed a zero-order kinetics during the rapid oxidation phase and MnB1 achieved the highest oxidation rate with different Cr(III) forms. In the leaching experiment, both of the robust manganese oxidizing bacteria MnB1 and the indigenous microorganisms significantly enhanced Cr(III) oxidation in soil. These findings highlight the critical role of BioMnO structure in driving Cr(III) oxidation and offer deeper insights into the biogeochemical cycling of chromium in the natural and contaminated environments.
铬（III）氧化为铬（VI）在铬的生物地球化学循环中起着关键作用，尤其是在土壤中。本研究通过生成生物源锰氧化物（BioMnO），研究了三株锰氧化细菌：恶臭假单胞菌MnB1、缺陷短波单胞菌MnO-2和芦苇泛菌MnO-3介导的铬（III）氧化。与MnO-2（2.50%）和MnO-3（3.26%）生成的BioMnO相比，MnB1生成的BioMnO表现出更高的铬（III）氧化效率（82.00%）。结构表征（XRD、SEM、TEM、XPS）表明，MnB1衍生的BioMnO具有三个独特的结构特征：无序层状结构、丰富的氧空位和升高的Mn（III/IV）比率，这些特征协同提高了铬（III）氧化的活性位点可用性。值得注意的是，只有MnB1系统能够有效氧化微溶性铬（III）形态（如Cr（OH）、CrFe（OH）），这些结构优势直接导致了其82.00%的卓越效率。动力学分析表明，在快速氧化阶段，铬（III）氧化遵循零级动力学，并且MnB1对不同的铬（III）形态具有最高的氧化速率。在浸出实验中，强大的锰氧化细菌MnB1和本地微生物都显著增强了土壤中铬（III）的氧化。这些发现突出了BioMnO结构在驱动铬（III）氧化中的关键作用，并为自然和污染环境中铬的生物地球化学循环提供了更深入的见解。
